Ophthalmology

Key Facts

Conjunctivitis is usually benign and self-limiting but must be distinguished from sight-threatening causes of red eye. Bacterial conjunctivitis improves without treatment in 65% within 5 days.

Epidemiology

• Most common eye condition seen in primary care
• Viral conjunctivitis: most common overall; highly contagious
• Bacterial: more common in children
• Allergic: affects 15-20% of population (often with atopy)

Aetiology

• Bacterial: S. aureus, S. pneumoniae, H. influenzae, Moraxella; gonococcal (hyperacute); chlamydial (chronic)
• Viral: adenovirus (most common), herpes simplex, enterovirus
• Allergic: seasonal (pollen), perennial (house dust mite), vernal, atopic

Pathophysiology

• Viral: lymphocytic infiltrate; often associated with conjunctival follicles
• Bacterial: neutrophilic infiltrate; purulent discharge

Bacterial

• Purulent/mucopurulent discharge
• Crusting of eyelids (stuck together on waking)
• Usually starts unilateral, becomes bilateral
• Mild discomfort (gritty)
• Normal vision

Viral

• Watery discharge
• Preauricular lymphadenopathy
• Often follows or accompanies URTI
• Bilateral (may start unilateral)
• Follicular reaction on eversion of lid
• Highly contagious (2-3 week course)

Allergic

• Itching (hallmark - distinguishes from infective)
• Watery discharge
• Bilateral
• Chemosis (conjunctival oedema)
• Seasonal pattern (hay fever association)
• Papillary reaction on lid eversion

Red Flags (NOT Simple Conjunctivitis)

• Reduced visual acuity
• Severe pain
• Photophobia
• Corneal involvement (opacity, ulcer)
• Contact lens wearer
• Neonatal (ophthalmia neonatorum)
• Hyperacute onset with profuse purulent discharge (gonococcal)

Bedside

• Visual acuity (must be normal in simple conjunctivitis)
• External eye examination (discharge character, lid involvement)
• Evert upper lid (follicles vs papillae)
• Fluorescein staining (exclude corneal involvement)

Bloods

• Not needed for routine conjunctivitis

Imaging

• Not needed

Special Tests

• Conjunctival swab: if gonococcal or chlamydial suspected (MC&S + NAAT)
• Slit lamp: if uncertain diagnosis or red flags
• Neonatal: urgent conjunctival swab for gonococcus and chlamydia

Non-pharmacological

• Hygiene: hand washing, avoid sharing towels; avoid rubbing eyes
• Cool compresses: allergic conjunctivitis
• Lid cleaning: warm compresses, cotton wool with cooled boiled water
• Remove contact lenses until fully resolved

Pharmacological

• Bacterial:
  • Chloramphenicol 0.5% drops QDS + 1% ointment at night for 5-7 days (first-line)
  • Fusidic acid 1% drops BD for 7 days (alternative; better adherence)
  • Most cases self-limit within 5-7 days even without antibiotics
• Gonococcal: IM ceftriaxone 500mg single dose + saline irrigation; same-day ophthalmology referral
• Chlamydial: oral azithromycin 1g single dose or doxycycline 100mg BD for 7 days; GUM referral for sexual health screening
• Viral: self-limiting (2-3 weeks); lubricant drops for comfort; no antiviral unless HSV suspected (aciclovir 3% ointment 5×/day)
• Allergic:
  • Mast cell stabiliser: sodium cromoglicate 2% QDS
  • Dual-action antihistamine/mast cell: olopatadine 0.1% BD
  • Oral antihistamine: cetirizine 10mg OD or loratadine 10mg OD
  • Avoid rubbing eyes; cold compresses
  • Short course of mild steroid drops (fluorometholone) for severe cases - specialist only

Surgical/Interventional

• Not applicable for routine conjunctivitis

Referral Criteria

• Reduced vision, severe pain, photophobia: urgent ophthalmology
• Contact lens wearer: urgent (exclude keratitis)
• Neonatal conjunctivitis: urgent ophthalmology + paediatrics
• Hyperacute purulent discharge: same-day ophthalmology (gonococcal)
• Chronic conjunctivitis not responding to treatment: ophthalmology

• Bacterial: resolves within 5-7 days; 65% resolve without antibiotics
• Viral: self-limiting in 2-3 weeks; epidemic keratoconjunctivitis may cause subepithelial infiltrates persisting months
• Allergic: chronic relapsing course; well-controlled with topical treatment
• Gonococcal: can cause corneal perforation within 24-48 hours if untreated - emergency
• Chlamydial: chronic course; trachoma (chlamydial) is the leading infectious cause of blindness worldwide

Comparison of Conjunctivitis Types

Key Facts

Anterior uveitis is a sight-threatening condition requiring prompt ophthalmological assessment and treatment to prevent complications including posterior synechiae, cataract, and glaucoma.

Epidemiology

• Incidence: 15-25 per 100,000 per year
• Peak age: 20-50 years
• 50% are HLA-B27 positive
• Most common cause of non-traumatic anterior uveitis in young adults

Aetiology

• Idiopathic: ~50% of cases
• HLA-B27 associated: ankylosing spondylitis, reactive arthritis, psoriatic arthritis, IBD
• Infectious: herpes simplex, herpes zoster, syphilis, TB, Lyme disease
• Sarcoidosis: bilateral granulomatous uveitis with large KPs
• Behçet's disease: recurrent uveitis + oral/genital ulcers
• Juvenile idiopathic arthritis (JIA): in children; often asymptomatic; screening required

Pathophysiology

• Fibrin deposition can cause posterior synechiae (iris adheres to lens capsule)
• Chronic inflammation → secondary glaucoma (trabecular meshwork obstruction) and cataract (steroid-related or inflammatory)

Symptoms

• Unilateral painful red eye (deep aching)
• Photophobia (often consensual - light in other eye causes pain)
• Blurred vision
• Lacrimation
• Small pupil (miosis) - due to sphincter spasm

Signs

• Ciliary flush (circumcorneal injection)
• Cells and flare in anterior chamber (slit lamp)
• Keratic precipitates (KPs): deposits on corneal endothelium
  • Small KPs: non-granulomatous (HLA-B27)
  • Large "mutton-fat" KPs: granulomatous (sarcoid, TB)
• Posterior synechiae: irregular pupil
• Hypopyon: layered white cells in anterior chamber (severe; Behçet's, HLA-B27)

Red Flags

• Bilateral uveitis (systemic cause likely)
• Recurrent episodes
• Granulomatous KPs (sarcoid, TB)
• Hypopyon (Behçet's, severe)
• In children (JIA - may be asymptomatic)
• Vitritis or retinal involvement (posterior uveitis - different management)

Bedside

• Visual acuity
• Slit lamp examination (cells, flare, KPs, synechiae)
• IOP measurement (may be low in acute uveitis; raised in chronic or steroid-induced)
• Fundoscopy (exclude posterior segment involvement)

Bloods

• First episode, unilateral, non-granulomatous: often no investigations needed
• Recurrent, bilateral, granulomatous, or atypical:
  • HLA-B27
  • ACE level, serum calcium (sarcoidosis)
  • Syphilis serology (VDRL/TPHA)
  • FBC, ESR/CRP
  • Quantiferon/T-SPOT (tuberculosis)
  • ANA (JIA in children)

Imaging

• CXR: sarcoidosis (bilateral hilar lymphadenopathy), TB
• Sacroiliac joint X-ray/MRI: if ankylosing spondylitis suspected

Special Tests

• OCT: macular oedema assessment
• Fluorescein angiography: if posterior involvement suspected

Non-pharmacological

• Sunglasses for photophobia
• Patient education about recurrence and when to seek help

Pharmacological

• Topical corticosteroid (mainstay):
  • Dexamethasone 0.1% drops: initially 1-2 hourly then taper over 6-8 weeks
  • Prednisolone 1% drops: alternative
  • Taper slowly (too rapid withdrawal → rebound)
• Cycloplegic (prevents posterior synechiae + provides pain relief):
  • Cyclopentolate 1% TDS (or atropine 1% BD for severe cases)
• IOP management: if raised, topical timolol 0.5% BD or dorzolamide; avoid prostaglandin analogues (may worsen uveitis)
• Systemic treatment (for recurrent/severe/bilateral):
  • Consider systemic immunosuppression: methotrexate, azathioprine, mycophenolate
  • Biologic agents: adalimumab (anti-TNFα) - NICE approved for non-infectious uveitis (VISUAL trials)

Surgical/Interventional

• Cataract surgery: for steroid-induced or inflammatory cataract
• Intravitreal steroid implant (dexamethasone - Ozurdex): for chronic/recurrent uveitis

Referral Criteria

• All suspected anterior uveitis: urgent ophthalmology referral (same day or next day)
• Recurrent/bilateral/granulomatous: investigate for systemic cause
• Children with JIA: routine ophthalmology screening (every 3-6 months)

• Good visual prognosis with prompt treatment in most cases
• Recurrence: ~50% (higher in HLA-B27+)
• Complications: posterior synechiae (20%), glaucoma (10-20%), cataract (chronic/steroid-induced), cystoid macular oedema
• JIA-associated uveitis: can be insidious; screening is essential to prevent sight loss
• HLA-B27+ anterior uveitis: typically acute, unilateral, alternating, good response to topical steroids

Uveitis Classification

HLA-B27 Associated Conditions

Key Facts

Posterior uveitis is less common than anterior uveitis but carries a higher risk of permanent visual loss. Identifying the underlying cause is essential for appropriate treatment.

Epidemiology

• Accounts for 15-25% of all uveitis cases
• Toxoplasmosis is the most common infective cause globally
• CMV retinitis: rare since HAART but still occurs in immunocompromised
• More likely to cause permanent visual loss than anterior uveitis

Aetiology

• Infectious: toxoplasmosis, CMV, HSV/VZV, TB, syphilis, toxocara
• Non-infectious: sarcoidosis, Behçet's disease, Vogt-Koyanagi-Harada (VKH), sympathetic ophthalmia, birdshot chorioretinopathy
• Lymphoma (masquerade syndrome): can mimic chronic uveitis

Pathophysiology

• Vitreous cells and haze from inflammation
• Macular oedema is the most common cause of visual loss in posterior uveitis
• Retinal vasculitis may cause vessel occlusion and ischaemia

Symptoms

• Floaters (most common presenting symptom)
• Blurred vision (may be painless)
• Scotomata (visual field defects)
• Usually no pain (unless associated anterior uveitis)
• May be unilateral or bilateral

Signs

• Vitreous cells and haze
• Retinal or choroidal lesions on fundoscopy
• Retinal vasculitis (sheathing of vessels)
• Macular oedema
• Specific patterns:
  • Toxoplasma: focal retinitis adjacent to old scar ("satellite lesion"); vitritis ("headlight in fog")
  • CMV: haemorrhagic retinal necrosis ("pizza pie")
  • Sarcoid: periphlebitis ("candle-wax drippings")

Red Flags

• Rapidly progressive visual loss (CMV retinitis, acute retinal necrosis)
• Immunocompromised patient (opportunistic infections)
• Bilateral involvement (sarcoid, VKH, Behçet's)
• Chronic vitritis not responding to treatment (consider lymphoma masquerade)

Bedside

• Visual acuity (may be significantly reduced)
• Fundoscopy (dilated): retinal/choroidal lesions, vitreous haze
• Slit lamp: anterior segment involvement

Bloods

• FBC, ESR, CRP
• ACE, calcium (sarcoidosis)
• Syphilis serology (VDRL/TPHA/FTA-Abs)
• QuantiFERON-TB Gold / T-SPOT
• Toxoplasma IgG/IgM
• HIV test (if risk factors or CMV retinitis)

Imaging

• CXR (sarcoidosis, TB)
• OCT (macular oedema)
• Fluorescein angiography (retinal vasculitis, ischaemia)
• CT/MRI chest: sarcoidosis staging

Special Tests

• Aqueous/vitreous tap + PCR: for viral causes (CMV, HSV, VZV, toxoplasma)
• Vitreous biopsy: if lymphoma suspected
• Indocyanine green angiography (ICG): choroidal lesions

Non-pharmacological

• MDT approach: ophthalmology, infectious diseases, respiratory (sarcoid/TB), rheumatology

Pharmacological

• Toxoplasmosis: pyrimethamine 25-50mg + sulfadiazine 1g QDS + folinic acid (for 6-8 weeks); oral prednisolone added after 48h of antimicrobials
  • Alternative: co-trimoxazole + prednisolone
• CMV retinitis: valganciclovir 900mg BD induction (21 days) then 900mg OD maintenance; intravitreal ganciclovir implant
  • Optimise ART in HIV patients
• Sarcoidosis: topical/periocular/systemic steroids; steroid-sparing: methotrexate, azathioprine, mycophenolate; anti-TNFα (adalimumab)
• TB: standard anti-TB treatment (RIPE) + corticosteroids (to prevent inflammatory damage)
• Syphilis: IV benzylpenicillin 18-24 MU daily for 14 days (neurosyphilis regimen)
• Non-infectious (general): systemic corticosteroids ± immunosuppression

Surgical/Interventional

• Intravitreal steroid injections (triamcinolone, dexamethasone implant)
• Vitrectomy: diagnostic (lymphoma) or therapeutic (severe vitritis, epiretinal membrane)
• Laser: for retinal neovascularisation or ischaemia

Referral Criteria

• All posterior uveitis: urgent ophthalmology referral
• Immunocompromised with visual symptoms: same-day
• Suspected intraocular lymphoma: urgent

• Toxoplasmosis: good with treatment; recurrence in 50%; macular involvement causes permanent central visual loss
• CMV retinitis: controlled with treatment but relapses common if immune suppression persists
• Sarcoid uveitis: chronic relapsing; may require long-term immunosuppression; good visual prognosis if treated
• Macular oedema: most common cause of visual loss; responds to treatment but may recur
• Overall: posterior uveitis has worse visual prognosis than anterior uveitis

Key Fundoscopic Appearances in Posterior Uveitis

Key Facts

Glaucoma is often called the "silent thief of sight" because it is typically asymptomatic until significant irreversible visual field loss has occurred. Early detection and treatment are essential.

Epidemiology

• ~700,000 affected in the UK; ~2% of >40s
• Leading cause of irreversible blindness worldwide
• 50% of cases remain undiagnosed
• Prevalence increases with age: 1% at 40, 5% at 80

Aetiology

• Primary open-angle glaucoma (POAG): open drainage angle; impaired trabecular meshwork outflow
• Primary angle-closure glaucoma (PACG): anatomically narrow angle; see separate topic for acute angle-closure
• Secondary: steroid-induced, uveitic, neovascular (proliferative diabetic retinopathy), pseudoexfoliation, pigment dispersion
• Congenital/developmental: rare; present in infancy with buphthalmos

Pathophysiology

• IOP determined by aqueous humour production (ciliary body) and drainage (trabecular meshwork → canal of Schlemm; or uveoscleral outflow)
• In POAG: increased resistance to outflow through trabecular meshwork

• Vascular factors (reduced optic disc perfusion) also contribute, especially in normal-tension glaucoma

POAG

• Asymptomatic until advanced (peripheral vision lost first; central preserved until late)
• Detected at routine optometry: raised IOP, suspicious disc, field defect
• Bilateral but often asymmetric
• No pain or redness

Symptoms of Advanced Disease

• Tunnel vision
• Difficulty with mobility (bumping into things)
• Near-misses (driving)
• Eventually total blindness if untreated

Red Flags

• Rapid visual field loss (suspect secondary cause or poor compliance)
• Young patient with glaucoma (consider secondary causes, congenital)
• Unilateral raised IOP with inflammation (uveitic glaucoma)
• IOP >40mmHg (acute angle-closure or secondary cause)

Bedside

• Visual acuity
• IOP measurement: Goldmann applanation tonometry (gold standard); normal 10-21mmHg
• Gonioscopy: angle assessment (open vs closed)

Bloods

• Not routinely needed

Imaging

• OCT (optical coherence tomography): retinal nerve fibre layer (RNFL) thickness; detects early damage before visual field loss
• Visual field testing (Humphrey/standard automated perimetry): detects arcuate scotoma, nasal step
• Optic disc photography: baseline and serial monitoring

Special Tests

• Central corneal thickness (CCT): thin cornea (≤555μm) underestimates true IOP and is an independent risk factor
• Disc assessment: cup-to-disc ratio (CDR), neuroretinal rim, disc haemorrhage, RNFL defects
• 24-hour IOP profile: for normal-tension glaucoma
• Repeat visual fields for confirmation (learning effect in first test)

Non-pharmacological

• Patient education about chronic nature and importance of adherence
• Driving standards (DVLA): must have adequate binocular visual field

Pharmacological (NICE NG81)

• First-line: prostaglandin analogue - latanoprost 0.005% drops OD at night
  • Side effects: eyelash growth, iris pigmentation (permanent), periorbital fat atrophy
  • Alternatives: bimatoprost, travoprost, tafluprost
• Second-line (if PGA insufficient/not tolerated): add or switch to:
  • Beta-blocker: timolol 0.5% BD (avoid in asthma, heart block, bradycardia)
  • Carbonic anhydrase inhibitor: dorzolamide 2% TDS or brinzolamide 1% BD
  • Alpha-2 agonist: brimonidine 0.2% BD
• Combination drops: available for adherence (e.g. Cosopt = timolol + dorzolamide; Ganfort = bimatoprost + timolol)
• Maximum medical therapy: combination of 2-3 agents from different classes

Surgical/Interventional

• Selective laser trabeculoplasty (SLT): can be first-line alternative to drops (LiGHT trial); well-tolerated; repeatable
• Trabeculectomy: gold standard surgical treatment for uncontrolled glaucoma; creates fistula for aqueous drainage
• Tube shunt/drainage device: for complex or refractory glaucoma
• Minimally invasive glaucoma surgery (MIGS): iStent, trabectome; for mild-moderate glaucoma (often combined with cataract surgery)
• Cyclophotocoagulation: for refractory end-stage glaucoma

Referral Criteria

• Raised IOP with suspicious disc or field defect: urgent ophthalmology referral
• Established glaucoma: lifelong ophthalmology follow-up
• Rapidly progressing: specialist glaucoma service

• POAG is a lifelong condition; treatment slows but does not reverse damage
• Treatment reduces IOP by 25-30% and significantly reduces visual field loss progression
• LiGHT trial: SLT as effective as drops for first-line IOP reduction

• Normal-tension glaucoma: treatment still beneficial (CNTGS trial: 30% IOP reduction slowed progression)
• CVI registration: approximately 10% of glaucoma patients become registered sight impaired
• Adherence is a major challenge (50% non-adherent at 1 year)

NICE NG81 - Treatment Pathway

Types of Glaucoma

Key Facts

AACG causes rapid, irreversible optic nerve damage if not treated promptly. It should be considered in any patient presenting with a painful red eye and reduced vision.

Epidemiology

• Incidence: 12-15 per 100,000 per year (UK)
• Female:male ratio 3:1
• Peak age: >60
• East Asian ethnicity: significantly higher risk (smaller eyes, shallower anterior chambers)
• Hypermetropic (long-sighted) patients at higher risk

Aetiology

• Anatomically predisposed eye (short axial length, shallow anterior chamber, thick lens, narrow angle)
• Pupillary block: mid-dilated pupil causes iris to bow forward → blocks trabecular meshwork
• Precipitants: dim lighting, mydriatic drugs (tropicamide), anticholinergics (oxybutynin, TCAs, ipratropium), sympathomimetics

Pathophysiology

Symptoms

• Severe unilateral eye pain (often frontal/periorbital)
• Reduced/blurred vision
• Haloes around lights (corneal oedema causes light diffraction)
• Nausea and vomiting (vagal response to pain; can mimic acute abdomen)
• Headache (can mimic migraine or stroke)
• Profuse lacrimation

Signs

• Red eye (mixed conjunctival and ciliary injection)
• Hazy/oedematous cornea (steamy)
• Semi-dilated, fixed (non-reactive) pupil - oval shaped
• Rock-hard eye (elevated IOP palpable through closed lids)
• Shallow anterior chamber (by slit lamp or pen torch - narrow shadow sign)
• IOP markedly elevated (often 40-80mmHg)

Red Flags

• This IS a red flag - any presentation matching above requires emergency management
• Fellow eye may have narrow angles (at risk of same episode)

Bedside

• Visual acuity (usually significantly reduced)
• IOP measurement (Goldmann tonometry): markedly elevated; if not available, palpation through closed lids (very firm)
• Pen torch: semi-dilated, oval, fixed pupil; shallow AC (narrow shadow sign)
• Slit lamp: corneal oedema, shallow AC, closed angle (gonioscopy when acute phase resolved)

Bloods

• Not needed for diagnosis
• U&Es if acetazolamide being used (electrolyte disturbance)

Imaging

• Anterior segment OCT/ultrasound biomicroscopy: angle assessment (specialist)
• B-scan ultrasound: if no view of posterior segment

Special Tests

• Gonioscopy: gold standard for angle assessment (performed after acute phase resolved)
• Fellow eye gonioscopy: assess for narrow angles (prophylactic iridotomy needed)

Emergency Treatment (Reduce IOP)

1. Lie patient supine (iris falls back, may partially open angle)
2. Pilocarpine 2% drops to affected eye: every 5 minutes × 3 then 4× daily (constricts pupil → opens angle)
   • Pilocarpine to fellow eye also (prophylactic)
3. Timolol 0.5% drops to affected eye: single dose (reduces aqueous production)
4. IV acetazolamide 500mg STAT (reduces aqueous production; oral 250mg QDS maintenance)
5. Topical steroid (dexamethasone 0.1%): reduces inflammation from acute episode
6. Analgesia: paracetamol ± opioid
7. Antiemetic: cyclizine 50mg IM/IV
8. If IOP not responding: IV mannitol 20% (1g/kg over 20 minutes) - osmotic diuretic
9. Pilocarpine may not work if IOP >50mmHg (sphincter ischaemia); must reduce IOP first with systemic agents

Definitive Treatment

• Performed once cornea has cleared (usually within 24-48 hours)
  • Both eyes treated (fellow eye prophylactic iridotomy - essential)
• Lens extraction (cataract surgery): removes the thick lens contributing to crowding; increasingly used as primary or early treatment

Surgical/Interventional

• Surgical peripheral iridectomy: if laser not possible
• Lens extraction: if angle-closure recurs despite PI or coexisting cataract
• Goniosynechialysis: to break peripheral anterior synechiae (specialist)

Referral Criteria

• AACG: immediate ophthalmology referral (same day/emergency)
• Fellow eye: prophylactic iridotomy arranged urgently
• Post-acute: ongoing glaucoma monitoring

• Prompt treatment (within hours): good visual prognosis; IOP reduces within hours of treatment
• Delayed treatment: permanent optic nerve damage; visual field loss; blindness
• After laser PI: recurrence is rare; fellow eye protected
• Chronic angle-closure may develop if repeated/prolonged episodes with synechiae formation
• Risk of further episodes in fellow eye is 40-80% without prophylactic treatment

Emergency AACG Treatment Summary

Risk Factors for Angle-Closure

Key Facts

Cataract surgery is one of the most cost-effective interventions in healthcare. Modern phacoemulsification has excellent outcomes with >95% of patients achieving improved vision.

Epidemiology

• ~30% of >65s have visually significant cataracts
• ~400,000 cataract operations/year in the UK (most common elective surgery)
• Prevalence increases with age: 50% by age 80
• Leading cause of blindness globally (mostly in developing world where surgical access is limited)

Aetiology

• Age-related (most common): nuclear sclerosis, cortical, posterior subcapsular
• Metabolic: diabetes mellitus (sorbitol accumulation → osmotic damage), galactosaemia
• Drug-induced: systemic corticosteroids (posterior subcapsular), amiodarone
• Traumatic: blunt or penetrating injury, radiation
• Congenital: genetic, intrauterine infection (rubella - TORCH)
• Secondary to ocular disease: uveitis, retinal detachment surgery, high myopia

Pathophysiology

• Lens opacification due to: protein denaturation and aggregation, oxidative damage, osmotic imbalance, UV-induced cross-linking
• Nuclear sclerotic: lens nucleus becomes yellow-brown → increased refractive index (myopic shift)
• Cortical: spoke-like opacities from cortex
• Posterior subcapsular: granular opacity on posterior lens capsule → early visual symptoms (affects near vision and causes glare)

Symptoms

• Gradual painless blurred vision (bilateral but often asymmetric)
• Glare (especially with oncoming headlights at night)
• Faded or yellowed colours
• Frequent spectacle changes (myopic shift with nuclear cataract)
• "Second sight" - temporary improvement in near vision (nuclear sclerosis increases refractive index)
• Monocular diplopia (rare)

Signs

• Reduced visual acuity (Snellen)
• Red reflex: absent or diminished on direct ophthalmoscopy
• Lens opacity visible on slit lamp examination
• Fundal view may be obscured

Red Flags

• Sudden visual loss (NOT cataract - consider retinal detachment, CRVO, CRAO, vitreous haemorrhage)
• Pain (NOT cataract - consider AACG, uveitis, keratitis)
• Young patient with cataract (consider secondary cause: diabetes, steroid, trauma, uveitis)
• Congenital cataract (urgent paediatric ophthalmology referral - amblyopia risk)

Bedside

• Visual acuity (Snellen chart): document for each eye
• Red reflex: using direct ophthalmoscope (absent = dense cataract)
• Slit lamp examination: cataract type and density
• Fundoscopy: assess retina (if visible through cataract)

Bloods

• Blood glucose/HbA1c: if diabetes suspected
• Not routinely needed for cataract assessment

Imaging

• Biometry (IOLMaster): measurement of axial length and corneal curvature for IOL power calculation (pre-operative)
• OCT: if macular pathology suspected (may limit visual outcome despite successful surgery)
• B-scan ultrasound: if fundal view obscured by dense cataract

Special Tests

• Pre-operative assessment: biometry, refraction, assessment of coexisting eye disease
• Check for amblyopia (may limit post-surgical visual improvement)

Non-pharmacological

• Updated spectacles: may temporarily improve vision in early cataract
• Brighter reading light: helpful in early stages
• Driving assessment: inform DVLA if cannot meet visual standards

Pharmacological

• No medical treatment effectively treats or prevents cataracts
• Pre-operative: topical chloramphenicol or povidone-iodine (infection prevention)
• Post-operative: topical steroid (dexamethasone 0.1% drops QDS for 4 weeks, taper) + topical NSAID (ketorolac/nepafenac)

Surgical/Interventional

• Phacoemulsification + IOL implantation: gold standard surgery
  • Day case under local anaesthetic (topical or sub-Tenon's)

• Operating time: 15-30 minutes
  • Visual recovery: days to weeks
• IOL options: monofocal (most common; glasses for near), multifocal/toric (corrects astigmatism)
• Second eye surgery: typically 1-3 months after first eye
• YAG laser capsulotomy: for posterior capsule opacification (outpatient, quick, painless)

Referral Criteria

• NICE NG77: refer when visual impairment affects quality of life/daily activities
• No specific visual acuity threshold required for referral
• Second eye surgery: if impaired binocular vision
• Congenital cataract: urgent paediatric ophthalmology (within days of detection)

• >95% of patients achieve improved vision after uncomplicated surgery
• Posterior capsule opacification: 20-30% at 5 years; easily treated with YAG capsulotomy
• Endophthalmitis: rare (1 in 1,000); sight-threatening; requires urgent intravitreal antibiotics
• Cystoid macular oedema: 1-2%; usually resolves with topical NSAIDs/steroids
• Retinal detachment: 1 in 1,000 (higher in high myopes)
• Cataract surgery reduces falls by 34% in older adults (Harwood 2005)
• Driving: most patients meet driving standards after surgery

Cataract Types and Associations

Complications of Cataract Surgery

Key Facts

AMD affects central vision while peripheral vision is preserved. Early detection of wet AMD and prompt anti-VEGF treatment are critical for preserving vision.

Epidemiology

• ~600,000 people in the UK; leading cause of certified sight impairment
• Prevalence rises sharply after 55: 10% of 65-74; 30% of >75
• Wet AMD causes 90% of severe visual loss from AMD despite being only 10% of cases

Aetiology

• Risk factors: age, smoking (2-3× risk), family history, APOE/CFH gene variants

Pathophysiology

• Drusen: extracellular deposits between RPE and Bruch's membrane; contain complement proteins, lipids; induce inflammation
• Geographic atrophy (dry): progressive loss of RPE and photoreceptors; central scotoma develops

Dry AMD

• Gradual central visual loss (months to years)
• Difficulty reading (small print, newspaper)
• Difficulty recognising faces
• Need for brighter lighting
• Drusen and RPE changes on fundoscopy

Wet AMD

• Rapid central visual loss (days to weeks)
• Metamorphopsia (straight lines appear wavy - Amsler grid positive)
• Central scotoma
• Fundoscopy: subretinal/intraretinal fluid, haemorrhage, grey-green CNV membrane

Red Flags

• Dense central scotoma affecting both eyes → CVI registration, low vision services

Bedside

• Visual acuity (Snellen)
• Amsler grid: metamorphopsia detection (distortion of grid lines)
• Fundoscopy (dilated): drusen, RPE changes, haemorrhage, CNV, atrophy

Bloods

• Not routinely needed

Imaging

• OCT (optical coherence tomography): gold standard for diagnosis and monitoring
  • Drusen, RPE atrophy, intraretinal/subretinal fluid, CNV
• Fundus fluorescein angiography (FFA): identifies CNV type and location
• OCT angiography (OCTA): non-invasive vascular imaging; detects CNV without dye injection
• Fundus autofluorescence (FAF): maps geographic atrophy

Special Tests

• Serial Amsler grid monitoring (dry AMD patients)
• Home monitoring devices (ForeseeHome) in high-risk patients

Non-pharmacological

• Smoking cessation (most important modifiable risk factor)
• Low vision aids: magnifiers, large print, electronic aids, lighting
• CVI registration: when eligible; access to social support
• Amsler grid self-monitoring: for dry AMD patients to detect wet conversion early
• Driving: inform DVLA if visual standards not met

Pharmacological

• Wet AMD - anti-VEGF intravitreal injections (NICE TA155, TA294, TA486):
  • Aflibercept (Eylea) 2mg: loading 3 monthly injections then treat and extend (8-16 weekly)
  • Ranibizumab (Lucentis) 0.5mg: monthly or PRN
  • Faricimab (Vabysmo): bispecific (anti-VEGF + anti-Ang2); longer intervals
  • Brolucizumab: potent but risk of intraocular inflammation
  • Treatment started within 14 days of diagnosis (NICE target)
• Dry AMD:
  • No specific treatment for early dry AMD
  • AREDS2 supplements: for intermediate AMD (vitamins C, E, zinc, copper, lutein, zeaxanthin) - reduce progression risk by 25%
  • Pegcetacoplan (C3 complement inhibitor): FDA-approved for geographic atrophy (emerging; not yet NICE-approved in UK at time of writing)

Surgical/Interventional

• Photodynamic therapy (PDT): verteporfin + laser; now rarely used (superseded by anti-VEGF)
• Submacular surgery: rarely performed; for large submacular haemorrhage (pneumatic displacement + anti-VEGF)

Referral Criteria

• Suspected wet AMD: urgent ophthalmology referral (aim treatment within 14 days)
• Dry AMD with drusen: optometrist monitoring; annual review
• CVI: when eligible for registration

• Dry AMD: slow progression over years; geographic atrophy causes gradual central vision loss; peripheral vision preserved
• Wet AMD (treated): anti-VEGF stabilises or improves vision in ~90%; mean gain of 8-15 letters (ANCHOR/MARINA/VIEW trials)
• Wet AMD (untreated): rapid loss of central vision over weeks-months
• Anti-VEGF treatment is ongoing (often for years); treatment burden is significant
• AREDS2 supplements: reduce progression from intermediate to advanced AMD by 25%
• Vision loss significantly impacts quality of life, independence, and mental health

Classification of AMD

Key Anti-VEGF Trials

Key Facts

Diabetic retinopathy is a microvascular complication of diabetes. Prevention through glycaemic and blood pressure control, early detection through screening, and timely treatment are the pillars of management.

Epidemiology

• ~4.9 million people with diabetes in the UK; ~1.4 million have some retinopathy
• Leading cause of blindness in 16-64 year olds
• Risk factors: duration of diabetes (most important), poor glycaemic control, hypertension, dyslipidaemia, pregnancy, nephropathy

Aetiology

• Chronic hyperglycaemia → microvascular damage to retinal capillaries
• Duration of diabetes is the strongest risk factor
• HbA1c is the most important modifiable factor (DCCT/UKPDS trials)

Pathophysiology

• Increased capillary permeability → macular oedema (fluid and lipid leakage)

Background Retinopathy (R1)

• Usually asymptomatic
• Microaneurysms (earliest sign; red dots)
• Dot and blot haemorrhages
• Hard exudates (lipid deposits - yellow waxy deposits)

Pre-proliferative (R2)

• Cotton wool spots (retinal nerve fibre layer infarcts)
• Venous beading and looping
• IRMA (intraretinal microvascular abnormalities)
• Deep dark blot haemorrhages
• Indicates worsening ischaemia

Proliferative (R3)

• New vessels on disc (NVD) or elsewhere (NVE)
• Pre-retinal or vitreous haemorrhage (sudden visual loss)
• Tractional retinal detachment (if fibrovascular proliferation)
• Rubeosis iridis (new vessels on iris) → neovascular glaucoma

Diabetic Maculopathy (M1)

• Reduced central visual acuity
• Hard exudates within 1 disc diameter of fovea
• Clinically significant macular oedema (CSMO)

Red Flags

• Sudden visual loss (vitreous haemorrhage, retinal detachment)
• New vessels on examination
• Rubeosis (new iris vessels - neovascular glaucoma imminent)
• Macular involvement (central visual threat)

Bedside

• Visual acuity (Snellen)
• Dilated fundoscopy (slit lamp biomicroscopy)
• NHS DESP screening photograph

Bloods

• HbA1c (glycaemic control)
• BP measurement (target <140/80)
• Lipid profile
• U&Es (nephropathy associated with worse retinopathy)

Imaging

• OCT: gold standard for macular oedema assessment (fluid, thickness)
• Fundus fluorescein angiography (FFA): identifies ischaemia, leakage, neovascularisation
• Wide-field retinal imaging: captures peripheral retina

Special Tests

• Grading of retinopathy (NSC classification: R0-R3, M0-M1)
• 7-field stereo photography (research gold standard)

Non-pharmacological

• Glycaemic control: HbA1c <53 mmol/mol (7%); DCCT: 76% reduction in retinopathy progression with intensive control
• Blood pressure control: target <140/80 (UKPDS: 34% reduction with tight BP control)
• Lipid management: statins as per cardiovascular risk
• Annual screening: NHS DESP; more frequent if higher-grade retinopathy
• Smoking cessation

Pharmacological

• Diabetic macular oedema (centre-involving):
  • Anti-VEGF intravitreal injections: aflibercept 2mg or ranibizumab 0.5mg (NICE TA274/TA346)
  • Loading: 3-6 monthly injections then PRN/treat and extend
• Non-centre-involving macular oedema: macular laser photocoagulation
• Intravitreal steroid implant (dexamethasone - Ozurdex; fluocinolone - Iluvien): for persistent DMO, especially pseudophakic patients

Surgical/Interventional

• Pan-retinal photocoagulation (PRP): for proliferative retinopathy

• Side effects: reduced peripheral vision, reduced night vision
• Macular laser: focal/grid laser for non-centre-involving DMO
• Vitrectomy: for non-clearing vitreous haemorrhage, tractional retinal detachment involving macula, epiretinal membrane

Referral Criteria

• R1 (background): annual screening
• R2 (pre-proliferative): ophthalmology referral within 13 weeks
• R3 (proliferative): urgent ophthalmology referral within 2 weeks
• M1 (maculopathy): ophthalmology referral within 13 weeks
• Sudden visual loss: emergency ophthalmology referral

• Background retinopathy: not sight-threatening; requires monitoring and risk factor optimisation
• Proliferative retinopathy: sight-threatening without treatment; PRP prevents severe visual loss in >95% (DRS trial)
• Diabetic macular oedema: anti-VEGF improves visual acuity (DRCR.net Protocol T: aflibercept superior for worse baseline VA)
• Tight glycaemic control: DCCT showed 76% reduction in retinopathy development; UKPDS confirmed in type 2
• Screening: NHS DESP has significantly reduced diabetes-related blindness in the UK

NHS Diabetic Eye Screening Classification

Key Trials

Key Facts

The retina is the only place in the body where arterioles can be directly visualised, making fundoscopy invaluable for assessing hypertensive end-organ damage.

Epidemiology

• Retinal changes present in ~10% of people with hypertension
• Severe retinopathy (grade III-IV) is uncommon with current BP management
• Malignant hypertension: incidence ~1-2 per 100,000/year

Aetiology

• Chronic hypertension: gradual arteriolar changes (sclerosis, narrowing, AV nipping)
• Acute/severe hypertension (malignant/accelerated): acute retinal damage (haemorrhages, exudates, papilloedema)

Pathophysiology

Grading (Keith-Wagener-Barker)

• Grade I: mild arteriolar narrowing (subtle; increased light reflex - "copper wiring")
• Grade II: moderate arteriolar narrowing + AV nipping/nicking (arteriole indents venule at crossings)
• Grade III: flame haemorrhages, cotton wool spots, hard exudates, macular star
• Grade IV: all of grade III + papilloedema (disc swelling)

Symptoms

• Grades I-II: usually asymptomatic
• Grade III: may have visual symptoms (blurring)
• Grade IV: headache, visual disturbance, symptoms of malignant hypertension (nausea, confusion, chest pain)

Red Flags

• Grade III-IV: malignant hypertension - medical emergency
• Papilloedema: indicates end-organ damage; requires urgent BP reduction
• Branch/central retinal vein occlusion (complication of chronic hypertensive retinopathy)

Bedside

• Blood pressure (essential; repeated measurements)
• Fundoscopy (dilated): grade retinopathy
• Visual acuity
• Urinalysis (proteinuria - renal end-organ damage)

Bloods

• U&Es (renal function)
• FBC (anaemia exacerbates retinopathy)
• HbA1c (exclude diabetes)
• Lipid profile

Imaging

• OCT: macular oedema, disc swelling quantification
• FFA: if diagnostic uncertainty
• Renal USS: if secondary hypertension suspected
• ECG/echocardiography: LVH assessment

Special Tests

• 24-hour ambulatory BP monitoring
• Secondary hypertension screen if young or refractory

Non-pharmacological

• Lifestyle: salt reduction (<6g/day), weight loss, exercise, alcohol moderation, smoking cessation

Pharmacological

• Treat the underlying hypertension (NICE NG136):
  • Step 1: ACE inhibitor (ramipril 1.25-10mg OD) or ARB; CCB (amlodipine 5-10mg OD) if >55 or African-Caribbean
  • Step 2: ACEi/ARB + CCB
  • Step 3: ACEi/ARB + CCB + thiazide-like diuretic (indapamide 2.5mg OD)
  • Step 4: add spironolactone 25-50mg OD (if K+ ≤4.5)
• Malignant hypertension (grade IV): admit; IV antihypertensives (labetalol, sodium nitroprusside); reduce BP gradually (25% in first 24 hours; avoid precipitous drop)
• Target: <140/90 (or <130/80 if diabetes/CKD)

Surgical/Interventional

• Not applicable for retinopathy itself
• Retinal changes improve with BP control

Referral Criteria

• Grade III-IV: emergency medical admission for BP management
• Grade I-II: optimise BP in primary care
• Visual symptoms: ophthalmology referral
• Suspected secondary hypertension: specialist referral

• Grade I-II: reversible arteriolar changes with BP control; does not directly threaten vision
• Grade III: haemorrhages and exudates usually resolve over weeks-months with BP treatment
• Grade IV: papilloedema resolves with BP control; untreated malignant hypertension has 90% 1-year mortality
• Complications: branch/central retinal vein occlusion (from AV nipping), macular oedema
• Good BP control prevents progression and reduces cardiovascular morbidity/mortality

Keith-Wagener-Barker Classification

Fundoscopic Signs of Hypertensive Retinopathy

Key Facts

Retinal detachment is a surgical emergency. Prompt diagnosis and treatment (especially before macula detaches) significantly improves visual outcome.

Epidemiology

• Incidence: 10-15 per 100,000/year
• Peak age: 60-70 (PVD-related); also younger myopes
• Bilateral in 10% (lifetime risk in fellow eye)
• Male > female

Aetiology

• Rhegmatogenous (most common ~90%): retinal break (tear or hole) allows vitreous fluid to enter subretinal space
  • Usually precipitated by PVD
• Tractional: fibrovascular membranes pull retina off RPE (proliferative diabetic retinopathy, ROP)
• Exudative/serous: fluid accumulates beneath retina without a break (uveitis, tumour, pre-eclampsia)

Pathophysiology

Symptoms

• Flashes (photopsia): light flashes in peripheral vision (vitreous traction on retina)
• Floaters: sudden shower of new floaters (vitreous haemorrhage or pigment cells - "tobacco dust"/Shafer's sign)
• Visual field defect: curtain or shadow spreading across vision (corresponds to location of detachment)
• Reduced visual acuity: if macula involved ("macula-off")

Signs

• Reduced visual acuity (macula-off)
• RAPD (relative afferent pupillary defect) if extensive detachment
• Elevated retina visible on fundoscopy (billowing grey membrane)
• Retinal tear visible
• Vitreous haemorrhage (may obscure view)
• Reduced red reflex

Red Flags

• Sudden new flashes and floaters → urgent fundoscopy (same day)

Bedside

• Visual acuity: critical (documents macula status)
• RAPD: present in extensive detachment
• Dilated fundoscopy (indirect ophthalmoscopy): identify break, extent of detachment, macula status

Bloods

• Not needed

Imaging

• B-scan ultrasound: if fundal view obscured (vitreous haemorrhage, dense cataract)
• OCT: for subtle macular detachment

Special Tests

• Slit lamp with contact lens: detailed retinal break identification
• Wide-field imaging: map extent of detachment

Emergency Management

• Macula-on RD: surgery within 24 hours (preserve macular function)
• Macula-off RD: surgery within 7 days (some centres sooner)
• Positioning: may be advised to position to prevent progression (e.g. lie on side to prevent superior detachment involving macula)

Surgical/Interventional

• Scleral buckle: silicone band applied externally to indent sclera → closes retinal break; often used in young phakic patients

• Laser retinopexy/cryotherapy: for retinal tears without detachment (prophylactic treatment to prevent RD)

Post-operative

• Posturing: head position to keep gas bubble against retinal break (may be required for days-weeks)
• No flying until gas absorbed (typically 2-8 weeks depending on gas type; gas expands at altitude → IOP rise)
• Follow-up: monitor for re-detachment, PVR (proliferative vitreoretinopathy)

Referral Criteria

• New flashes and floaters: same-day ophthalmology assessment
• Retinal tear without detachment: urgent laser/cryotherapy
• Retinal detachment: emergency surgical referral
• Symptoms in fellow eye: urgent assessment

• Macula-on RD (repaired promptly): 90% anatomical success; >80% achieve good visual acuity
• Macula-off RD: anatomical success similar but visual recovery limited by duration of macular detachment
• Re-detachment rate: 5-10% (may require further surgery)
• PVR (proliferative vitreoretinopathy): scar tissue formation → re-detachment; most common cause of surgical failure (~5%)
• Fellow eye risk: 10% lifetime risk of RD in other eye
• Prophylactic laser for retinal tears reduces RD risk from ~50% to <5%

Types of Retinal Detachment

Urgency of Retinal Detachment Repair

Key Facts

RVO is a common cause of sudden painless visual loss in older adults. Cardiovascular risk factor management is essential alongside ophthalmic treatment.

Epidemiology

• Prevalence: 1-2% of adults >40
• BRVO is 4× more common than CRVO
• Mean age: BRVO 60-70; CRVO 65-75
• Second eye involvement: 5-15% over 5 years

Aetiology

• Hypertension: most important risk factor (present in >60%)
• Glaucoma: independent risk factor for CRVO
• Diabetes, hyperlipidaemia, smoking
• Hyperviscosity: polycythaemia, myeloma, Waldenström's
• Thrombophilia: consider in young patients (<50) with RVO (antiphospholipid, factor V Leiden)
• OCP: risk factor in young women

Pathophysiology

BRVO

• Sudden painless visual loss (or blurring) - often sector-specific
• Flame haemorrhages in one sector (along vein distribution)
• Cotton wool spots, dilated tortuous veins in affected sector
• Macular oedema (if superotemporal branch - most common - affects macula)

CRVO

• Sudden painless visual loss (more severe than BRVO)
• "Stormy sunset" fundus: extensive haemorrhages in ALL quadrants
• Dilated, tortuous veins throughout
• Disc oedema
• Cotton wool spots
• Macular oedema

CRVO Subtypes

• Non-ischaemic (75%): moderate visual loss, good prognosis, fewer haemorrhages
• Ischaemic (25%): severe visual loss (VA <6/60), extensive haemorrhages, RAPD, high risk of neovascularisation

Red Flags

• VA <6/60 with RAPD → ischaemic CRVO
• Young patient (<50) with RVO → investigate for thrombophilia

Bedside

• Visual acuity
• RAPD (ischaemic CRVO)
• Dilated fundoscopy
• IOP (glaucoma screening)
• Blood pressure

Bloods

• Cardiovascular screen: BP, HbA1c, lipid profile
• FBC (polycythaemia, leukaemia)
• ESR, plasma viscosity
• U&Es, TFTs
• Thrombophilia screen if <50: antiphospholipid antibodies, lupus anticoagulant, factor V Leiden, protein C/S, antithrombin III
• Serum protein electrophoresis (hyperviscosity)

Imaging

• OCT: macular oedema assessment (central macular thickness)
• Fundus fluorescein angiography (FFA): identifies ischaemia, non-perfusion areas, neovascularisation
• OCT angiography: non-invasive assessment of perfusion

Special Tests

• Gonioscopy: for neovascular glaucoma screening
• Visual field testing: BRVO sector defect

Non-pharmacological

• Cardiovascular risk factor management: BP control, smoking cessation, diabetes management, lipid control
• Serial monitoring: OCT, IOP, gonioscopy for neovascularisation

Pharmacological

• Macular oedema (centre-involving):
  • Anti-VEGF intravitreal injections: aflibercept 2mg or ranibizumab 0.5mg (NICE TA283 for CRVO; TA409 for BRVO)
  • Loading: monthly × 3, then PRN or treat and extend
• Intravitreal dexamethasone implant (Ozurdex): alternative for RVO-related macular oedema; lasts ~4 months; risk of IOP rise and cataract
• No role for anticoagulation or antiplatelet therapy in RVO treatment

Surgical/Interventional

• Pan-retinal photocoagulation (PRP): for neovascularisation (NVI, NVD, NVE) - prevents neovascular glaucoma
• Sector laser: for BRVO with non-perfusion and neovascularisation
• Anti-VEGF intravitreal injection: for neovascular glaucoma
• Vitrectomy: for non-clearing vitreous haemorrhage

Referral Criteria

• All RVO: ophthalmology referral (within 1-2 weeks)
• Ischaemic CRVO or rubeosis: urgent ophthalmology
• Cardiovascular risk factors: GP management with monitoring

• BRVO: good prognosis; 60% improve spontaneously; anti-VEGF for macular oedema achieves mean 10-15 letter improvement
• Non-ischaemic CRVO: moderate prognosis; 33% convert to ischaemic over time
• Ischaemic CRVO: poor visual prognosis; 60% risk of neovascular glaucoma within 3 months ("100-day glaucoma")
• Anti-VEGF significantly improves visual outcomes for macular oedema in both BRVO and CRVO
• Cardiovascular risk: patients with RVO have increased risk of stroke, MI, and cardiovascular death

CRVO: Non-Ischaemic vs Ischaemic

Key Facts

CRAO is effectively a retinal stroke. The priority is to identify the cause, exclude GCA, and assess/reduce future vascular risk.

Epidemiology

• Incidence: approximately 1-2 per 100,000/year
• Mean age: 60-65
• Male > female
• 25% of CRAO patients have a stroke or MI within 5 years

Aetiology

• Embolism (most common): carotid atherosclerosis, cardiac source (AF, endocarditis, mural thrombus)
• Thrombosis in situ: atherosclerosis of retinal artery
• Giant cell arteritis (5-10% of CRAO): arteritis of ophthalmic/ciliary arteries; medical emergency
• Other: vasculitis, hypercoagulable states, sickle cell, dissection
• BRAO: almost always embolic (cholesterol, platelet-fibrin, calcific emboli)

Pathophysiology

• CRA supplies inner 2/3 of retina; outer 1/3 supplied by choroid

• Cherry red spot: fovea appears red because it is supplied by choroidal circulation (normal colour against pale ischaemic surrounding retina)
• Cilioretinal artery (present in 30%): branch from ciliary circulation; may preserve central macular perfusion → better visual prognosis

CRAO

• Sudden, painless, profound monocular visual loss (counting fingers or worse)
• Usually unilateral
• Vision may fluctuate initially (if incomplete occlusion)

Signs

• Pale, oedematous retina with cherry red spot at macula
• RAPD (relative afferent pupillary defect)
• Attenuated arterioles ("box-carring" - segmentation of blood column)
• Visible embolus (Hollenhorst plaque - refractile cholesterol crystal at bifurcation)
• Optic disc pallor (develops later)

BRAO

• Sector visual field loss (corresponding to occluded branch)
• Pallor in affected sector of retina
• Visible embolus at arteriolar bifurcation
• Better visual prognosis than CRAO

Red Flags

• Age >50: always exclude GCA (headache, jaw claudication, scalp tenderness, PMR symptoms, raised ESR/CRP)
• Amaurosis fugax (transient monocular visual loss): warning sign of impending CRAO or stroke
• Young patient: investigate for thrombophilia, vasculitis

Bedside

• Visual acuity (usually severely reduced in CRAO)
• RAPD testing (positive)
• Dilated fundoscopy (cherry red spot, pale retina, attenuated arterioles)
• Blood pressure
• Pulse (irregular - AF)

Bloods - URGENT

• ESR and CRP (must exclude GCA in >50; ESR >50mm/hr highly suggestive)
• FBC (polycythaemia, thrombocytosis)
• Glucose, HbA1c, lipid profile
• Clotting, thrombophilia screen (if <50)
• Blood cultures (if endocarditis suspected)

Imaging

• Carotid duplex ultrasound: carotid stenosis assessment
• Echocardiography: cardiac source of emboli (TTE/TOE)
• ECG: atrial fibrillation
• CT/MRI brain: if stroke symptoms
• FFA: confirms diagnosis (delayed arterial filling, "pruned tree" appearance)
• OCT: retinal oedema, inner retinal thickening

Special Tests

• Temporal artery biopsy: if GCA suspected (within 2 weeks of starting steroids; do not delay steroids for biopsy)
• 24-hour ECG (Holter): paroxysmal AF

Emergency

• Exclude GCA: if >50 and clinical suspicion → start prednisolone 60-80mg OD immediately (do not wait for biopsy) + PPI
• No proven effective acute treatment for non-arteritic CRAO (window for intervention is ~90 minutes; most present later)
• Attempted treatments (limited evidence): ocular massage, anterior chamber paracentesis (reduces IOP to dislodge embolus), intraarterial thrombolysis (research only; EAGLE study showed no benefit), hyperbaric oxygen

Non-pharmacological

• Stroke pathway referral: CRAO is a stroke equivalent; high short-term risk of cerebral stroke and MI
• Cardiovascular risk factor management: BP control, smoking cessation, statin, antiplatelet
• Carotid endarterectomy: if significant ipsilateral carotid stenosis (>70% symptomatic)

Pharmacological

• Antiplatelet: aspirin 75mg OD (unless anticoagulation indicated)
• Statin: atorvastatin 80mg OD
• Anticoagulation: if AF identified (DOAC or warfarin)
• GCA treatment: prednisolone 60-80mg OD → slow taper over 1-2 years; consider tocilizumab (NICE TA518 - GiACTA trial)

Surgical/Interventional

• Carotid endarterectomy: if ipsilateral carotid stenosis >70% (symptomatic)
• PFO closure: if paradoxical embolism suspected in young patients

Referral Criteria

• CRAO: emergency ophthalmology + acute stroke pathway
• Suspected GCA: immediate high-dose steroids + urgent temporal artery biopsy
• Amaurosis fugax: urgent TIA clinic/vascular assessment
• Young patient: haematology/rheumatology for thrombophilia/vasculitis screen

• CRAO visual prognosis: poor; only 10-20% recover useful vision
• Cilioretinal artery sparing: better outcome (may retain some central vision)
• BRAO: better prognosis; majority recover to 6/12 or better
• GCA-related CRAO: irreversible if not treated rapidly; 50% risk of fellow eye involvement without steroids
• Cardiovascular risk: 25% risk of stroke or MI within 5 years after CRAO
• Amaurosis fugax: 10-15% risk of stroke within 3 months without treatment

CRAO vs CRVO Comparison

Types of Retinal Emboli

Key Facts

Optic neuritis is an inflammatory, demyelinating condition affecting the optic nerve. It is the most common cause of acute optic neuropathy in young adults and is strongly associated with multiple sclerosis. The Optic Neuritis Treatment Trial (ONTT) remains the landmark study guiding management.

Epidemiology

• Incidence: 1-5 per 100,000 per year in the UK
• Peak age: 20-40 years
• Female:male ratio 3:1
• More common in Caucasian populations and higher latitudes
• First presentation of MS in 20% of cases
• 50-70% of patients develop MS within 15 years (higher if MRI abnormalities at presentation)

Aetiology

• Demyelinating: MS (most common), neuromyelitis optica spectrum disorder (NMOSD/Devic disease), MOG antibody-associated disease
• Infectious: post-viral (measles, mumps, EBV), syphilis, Lyme disease, TB, toxoplasmosis
• Autoimmune: SLE, sarcoidosis, Behçet disease
• Drug-induced: ethambutol, isoniazid, chloroquine
• Idiopathic: no identifiable cause in some cases

Pathophysiology

• Autoimmune-mediated inflammatory demyelination of the optic nerve
• T-cell-mediated attack on myelin sheaths surrounding optic nerve axons
• Inflammation causes conduction block, resulting in acute visual loss
• Remyelination occurs during recovery, though may be incomplete
• Axonal loss can occur in severe or recurrent cases, leading to optic atrophy
• In NMOSD, AQP4 antibodies target astrocytes, causing more severe and bilateral disease

Typical Presentation

• Unilateral painful visual loss developing over hours to days (bilateral in children or NMOSD)
• Pain on eye movement (present in >90% of cases), typically periorbital
• Reduced visual acuity (ranges from mild blurring to complete loss of vision)
• Dyschromatopsia (impaired colour vision, particularly red desaturation) often disproportionate to acuity loss
• Central or centrocaecal scotoma on visual field testing
• Uhthoff phenomenon: worsening of symptoms with heat or exercise

Examination Findings

• Relative afferent pupillary defect (RAPD) on swinging light test (Marcus Gunn pupil)
• Reduced visual acuity (variable severity)
• Disc swelling in 35% (papillitis); disc appears normal in 65% (retrobulbar neuritis - 'the patient sees nothing and the doctor sees nothing')
• Reduced colour vision (Ishihara plates)

Red Flags

• Bilateral simultaneous optic neuritis (consider NMOSD or MOG)
• No pain (consider ischaemic optic neuropathy, compressive lesion)
• Progressive visual loss over weeks without recovery (consider compressive or infiltrative lesion)
• Age >50 years (consider giant cell arteritis, ischaemic optic neuropathy)
• Severe visual loss to no perception of light (consider NMOSD)

Bedside

• Visual acuity (Snellen chart)
• Colour vision testing (Ishihara plates) - often disproportionately impaired
• Pupil examination for RAPD (swinging light test)
• Visual field testing (confrontation and formal perimetry) - central/centrocaecal scotoma
• Fundoscopy: disc swelling (papillitis) or normal (retrobulbar)

Bloods

• FBC, ESR, CRP (exclude GCA in older patients)
• AQP4 antibodies (anti-aquaporin-4) if NMOSD suspected
• MOG antibodies if atypical features
• ANA, anti-dsDNA if SLE suspected
• Syphilis serology, ACE level (sarcoidosis) in atypical cases

Imaging

• MRI brain and orbits with gadolinium: gold standard
  • Optic nerve enhancement and swelling on T1 post-contrast
  • T2 hyperintensity of optic nerve
  • White matter lesions (periventricular) suggest MS risk
  • ≥1 T2 lesion: 72% risk of MS at 15 years; 0 lesions: 25% risk (ONTT)

Special Tests

• Visual evoked potentials (VEPs): delayed P100 latency (even after clinical recovery)
• OCT (optical coherence tomography): thinning of retinal nerve fibre layer (RNFL) indicates axonal loss
• Lumbar puncture: oligoclonal bands (if MS workup needed)

Non-pharmacological

• Reassurance that visual recovery typically occurs over 4-6 weeks
• Urgent ophthalmology referral
• Neurology referral for MS workup if MRI abnormalities

Pharmacological

• IV methylprednisolone 1g daily for 3 days (ONTT protocol):
  • Accelerates visual recovery by 2-3 weeks
  • Does NOT alter final visual outcome at 6-12 months
  • Indicated for severe visual loss, bilateral disease, occupational need for rapid recovery
• Oral prednisolone alone is CONTRAINDICATED - increased recurrence rate (ONTT finding)
• Optional: oral prednisolone taper (1mg/kg for 11 days) after IV methylprednisolone
• If NMOSD confirmed: plasma exchange, IV immunoglobulin, long-term immunosuppression (rituximab, azathioprine, mycophenolate)

Surgical

• Not applicable for optic neuritis

Referral Criteria

• Urgent ophthalmology assessment within 24 hours
• Neurology referral for all patients (MS risk stratification)
• Neuro-ophthalmology specialist if atypical features
• Consider disease-modifying therapy (DMT) if MS diagnosed (e.g. dimethyl fumarate, natalizumab, ocrelizumab)

• 95% recover visual acuity to 6/9 or better within 12 months
• Recovery typically begins within 2-3 weeks and continues over months
• Residual colour vision deficit and contrast sensitivity loss are common despite good acuity recovery
• Risk of MS: 25% at 15 years if normal MRI; 72% if ≥1 white matter lesion (ONTT)
• Recurrence of optic neuritis: 35% within 10 years
• NMOSD carries a worse prognosis with 50% legally blind within 5-10 years if untreated
• MOG antibody-associated disease generally has better recovery than NMOSD

Optic Neuritis Treatment Trial (ONTT) Key Findings

MS Risk Stratification by MRI

Comparison of Optic Neuropathies

Key Facts

Papilloedema refers to bilateral swelling of the optic disc caused by raised intracranial pressure. It must be distinguished from other causes of disc swelling such as optic neuritis, ischaemic optic neuropathy, and disc drusen. Papilloedema is always a medical emergency until a serious underlying cause is excluded.

Epidemiology

• Incidence depends on underlying cause
• IIH incidence: 1-2 per 100,000 overall; 12-20 per 100,000 in obese women of childbearing age
• Space-occupying lesions, hydrocephalus, and venous sinus thrombosis are other common causes
• Can occur at any age

Aetiology

• Space-occupying lesion: primary or metastatic brain tumour, abscess
• Idiopathic intracranial hypertension (IIH): most common cause in young obese women
• Cerebral venous sinus thrombosis: particularly in prothrombotic states, OCP use
• Meningitis/encephalitis: infective or inflammatory
• Hydrocephalus: obstructive or communicating
• Malignant hypertension: BP >180/120 mmHg with end-organ damage
• Drugs: tetracyclines, vitamin A (retinoids), lithium, corticosteroid withdrawal

Pathophysiology

• Raised ICP is transmitted along the subarachnoid space surrounding the optic nerve
• Increased pressure impairs axoplasmic flow at the lamina cribrosa
• Axonal swelling causes disc elevation and blurring of disc margins
• Venous congestion leads to haemorrhages and cotton-wool spots
• Chronic papilloedema leads to axonal loss, optic atrophy, and permanent visual loss
• In IIH, impaired CSF absorption at arachnoid granulations is the proposed mechanism

Symptoms

• Headache: often worse on waking, exacerbated by bending, straining, coughing (Valsalva)
• Transient visual obscurations: brief (seconds) episodes of greying or blacking out of vision, often positional
• Diplopia: from abducens (VI) nerve palsy (false localising sign due to long intracranial course)
• Pulsatile tinnitus: synchronous with heartbeat
• Nausea and vomiting if ICP severely raised

Examination Findings

• Bilateral optic disc swelling with blurred disc margins
• Venous engorgement, loss of spontaneous venous pulsation
• Peripapillary flame haemorrhages and cotton-wool spots
• Enlarged blind spot on visual field testing
• Reduced visual acuity in advanced cases
• VI nerve palsy (unilateral or bilateral)

Red Flags

• Sudden severe headache with papilloedema (exclude SAH, venous sinus thrombosis)
• Rapidly declining visual acuity (fulminant IIH, urgent surgical intervention needed)
• Focal neurological signs (suggest space-occupying lesion)
• Papilloedema in a child (higher suspicion for posterior fossa tumour)
• New papilloedema during pregnancy

Bedside

• Visual acuity (Snellen chart)
• Pupil examination (RAPD in asymmetric cases)
• Colour vision (Ishihara plates)
• Visual field testing: enlarged blind spot is earliest finding; progressive field constriction
• Fundoscopy: bilateral disc swelling, haemorrhages, exudates
• Blood pressure measurement (exclude malignant hypertension)

Bloods

• FBC, U&Es, LFTs, coagulation screen
• ESR, CRP
• Thrombophilia screen if venous sinus thrombosis suspected

Imaging

• MRI brain with gadolinium: essential first-line to exclude SOL, hydrocephalus
• MR venography (MRV): to exclude cerebral venous sinus thrombosis
• CT head: if MRI not immediately available or contraindicated
• Do NOT perform LP before neuroimaging (risk of tonsillar herniation with SOL)

Special Tests

• Lumbar puncture (after imaging excludes SOL):
  • Opening pressure >25 cmH2O (adult, lateral decubitus) confirms raised ICP
  • CSF analysis: protein, glucose, cell count, cytology, culture
• OCT: retinal nerve fibre layer (RNFL) thickness to monitor and grade papilloedema
• Formal perimetry (Humphrey visual fields): serial monitoring of visual fields

Non-pharmacological

• Weight loss: target 5-10% body weight reduction in IIH (shown to reduce ICP and improve papilloedema)
• Treat underlying cause (tumour surgery, antibiotics for infection, anticoagulation for CVST)
• Serial visual field and OCT monitoring

Pharmacological

• Acetazolamide 250mg BD-QDS, titrate up to 2g/day (IIH Treatment Trial - IIHTT)
  • Carbonic anhydrase inhibitor reducing CSF production
  • Monitor U&Es (hypokalaemia), paraesthesiae, metabolic acidosis
• Topiramate 25-50mg BD: alternative or adjunct (also aids weight loss)
• Treat underlying cause: dexamethasone for SOL, anticoagulation for CVST
• Therapeutic LP can provide temporary relief of ICP

Surgical

• Optic nerve sheath fenestration: for progressive visual loss unresponsive to medical therapy
• CSF shunting (ventriculoperitoneal or lumboperitoneal): for refractory IIH with headache predominance
• Venous sinus stenting: emerging treatment for IIH with venous sinus stenosis

Referral Criteria

• Urgent ophthalmology and neurology referral for all cases of papilloedema
• Emergency neurosurgical referral if SOL or acute hydrocephalus
• Neuro-ophthalmology follow-up for monitoring visual function
• Bariatric surgery referral if BMI >40 and refractory IIH

• Prognosis depends on underlying cause and duration of papilloedema
• IIH: 25% experience permanent visual field loss; 5-10% develop significant visual impairment
• Fulminant IIH (rapid visual decline over days) carries high risk of blindness without urgent intervention
• Visual loss in chronic papilloedema is often insidious and irreversible once optic atrophy develops
• With appropriate treatment (weight loss, acetazolamide), >80% of IIH patients achieve resolution
• Recurrence of IIH: 10-40%, particularly with weight regain
• SOL-related papilloedema prognosis depends on tumour type and treatability

Frisén Grading of Papilloedema

Modified Dandy Criteria for IIH

IIH Treatment Trial (IIHTT) Key Results

Key Facts

Giant cell arteritis is a granulomatous vasculitis predominantly affecting medium and large arteries, particularly branches of the external carotid artery. It is an ophthalmic emergency because untreated GCA can cause irreversible bilateral blindness. Treatment must not be delayed pending diagnostic investigations.

Epidemiology

• Incidence: 15-25 per 100,000 in those >50 years
• Peak age: 70-80 years; virtually never occurs before age 50
• Female:male ratio 2-3:1
• More common in Northern European and Scandinavian populations
• Associated with polymyalgia rheumatica (PMR) in 40-60% of cases

Aetiology

• Exact cause unknown; likely multifactorial
• Genetic susceptibility: HLA-DR4 association
• Possible infectious triggers (varicella zoster virus has been implicated)
• Environmental factors: higher incidence at northern latitudes, seasonal variation
• Ageing-related immune dysregulation with loss of immune tolerance

Pathophysiology

• Granulomatous inflammation of arterial media and adventitia
• CD4+ T-cell and macrophage-mediated immune response
• Dendritic cells in vasa vasorum present antigen, triggering T-cell activation
• Giant cells and granulomata form at the internal elastic lamina
• Intimal hyperplasia leads to luminal narrowing and thrombosis
• Ischaemia of supplied tissues causes symptoms (visual loss from posterior ciliary artery occlusion)
• Can affect aorta and its major branches (large-vessel GCA)

Cranial GCA

• New-onset headache: temporal, unilateral or bilateral, severe
• Scalp tenderness: pain on brushing hair, wearing glasses
• Jaw claudication: pain on sustained chewing (most specific symptom, LR+ 4.2)
• Temporal artery abnormalities: thickened, tender, non-pulsatile, nodular
• Constitutional symptoms: fever, malaise, weight loss, night sweats

Visual Manifestations

• Anterior ischaemic optic neuropathy (AION): sudden painless visual loss, altitudinal field defect, pallid disc oedema
• Amaurosis fugax: transient monocular visual loss (warning sign)
• Central retinal artery occlusion: sudden painless complete visual loss
• Diplopia: from ischaemia of extraocular muscles or cranial nerves (III, IV, VI)
• Posterior ischaemic optic neuropathy: rare

Red Flags

• Any visual symptoms (amaurosis fugax, visual loss, diplopia) - ophthalmic emergency
• Bilateral visual loss (indicates contralateral involvement)
• Jaw claudication with new headache in patient >50 years
• Sudden unexplained visual loss in elderly patient
• Tongue claudication or necrosis (rare but pathognomonic)

Bedside

• Visual acuity and visual fields
• Fundoscopy: pallid disc oedema (arteritic AION), cherry-red spot (CRAO)
• Palpation of temporal arteries: tenderness, thickening, reduced pulsation
• Blood pressure in both arms (large-vessel GCA)

Bloods

• ESR: typically >50mm/h (often >100mm/h); normal in 4%
• CRP: typically markedly raised; more sensitive than ESR
• FBC: normocytic anaemia, thrombocytosis common
• LFTs: raised ALP in 30%
• Fibrinogen: elevated

Imaging

• Temporal artery ultrasound: 'halo sign' (hypoechoic ring around vessel) - sensitivity 77%, specificity 96% (TABUL study)
• MRI/MRA: can demonstrate temporal artery wall thickening and enhancement
• PET-CT: for large-vessel GCA assessment (aortitis, large-vessel inflammation)
• CTA: if large-vessel involvement suspected

Special Tests

• Temporal artery biopsy (≥1cm, ideally within 2 weeks of starting steroids):
  • Gold standard; sensitivity 77-90% (skip lesions can cause false negatives)
  • Shows granulomatous inflammation, giant cells, fragmented internal elastic lamina
  • Should NOT delay treatment - biopsy remains positive for up to 2-4 weeks after starting steroids

Non-pharmacological

• Do NOT delay treatment - start steroids immediately on clinical suspicion
• Patient education: symptoms of relapse, importance of adherence
• Bone protection: calcium, vitamin D, consider bisphosphonate (NICE NG176)
• PPI for gastroprotection

Pharmacological

• Without visual symptoms: prednisolone 40-60mg OD (BSR 2020 guidelines)
• With visual symptoms or jaw claudication: prednisolone 60-100mg OD or IV methylprednisolone 500mg-1g daily for 3 days then oral
• Slow taper: reduce by no more than 10mg every 2 weeks once stable; typical treatment duration 18-24 months
• Aspirin 75mg OD: consider for vascular protection (debated)
• Tocilizumab (IL-6 receptor antagonist) 162mg SC weekly: recommended as steroid-sparing agent (GiACTA trial, NICE TA518)
  • Relapse-free remission at 52 weeks: 56% (tocilizumab) vs 14% (placebo)
• Methotrexate 10-15mg weekly: alternative steroid-sparing agent

Surgical

• Temporal artery biopsy (diagnostic, not therapeutic)
• Vascular surgery referral if aortic aneurysm (large-vessel GCA)

Referral Criteria

• Same-day ophthalmology assessment if visual symptoms
• Rheumatology referral for all suspected GCA
• Vascular surgery if large-vessel involvement
• Urgent biopsy within 2 weeks of starting steroids

• Visual loss at presentation is usually irreversible - recovery rate only 5-15%
• Without treatment, 50-65% with unilateral visual loss develop bilateral involvement within 1-2 weeks
• With prompt treatment, risk of further visual loss is <1%
• Relapse occurs in 40-60% during steroid taper
• Aortic aneurysm risk: 17.3× higher than general population; affects 10-20% of GCA patients
• Median treatment duration: 2-3 years for steroid taper
• Mortality is not significantly increased with appropriate treatment
• Steroid-related morbidity is significant: osteoporosis, diabetes, infections

ACR 1990 Classification Criteria for GCA (≥3 of 5)

GiACTA Trial Key Results

Steroid Tapering Schedule (BSR 2020)

Key Facts

Orbital cellulitis is an acute infection of the soft tissues posterior to the orbital septum. It must be distinguished from the far more common and less serious preseptal (periorbital) cellulitis, which involves tissues anterior to the septum. Orbital cellulitis is a sight-threatening and potentially life-threatening emergency.

Epidemiology

• Most common in children and young adults
• More common in winter months (correlates with sinusitis prevalence)
• Annual incidence approximately 1.6 per 100,000 in children
• More common in males
• Pre-existing sinusitis is present in >90% of cases

Aetiology

• Sinusitis (most common cause, particularly ethmoid sinusitis via paper-thin lamina papyracea)
• Periorbital trauma or foreign body
• Post-surgical (sinus or orbital surgery)
• Dental infection (upper molars/premolars)
• Dacryocystitis (lacrimal sac infection)
• Haematogenous spread from distant infection
• Common organisms: Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, Haemophilus influenzae (children), anaerobes (Bacteroides, Peptostreptococcus), polymicrobial in many cases

Pathophysiology

• Infection spreads from sinuses to orbit via valveless ethmoidal veins or directly through thin orbital walls
• The lamina papyracea (medial orbital wall) is paper-thin and allows direct extension from ethmoid sinusitis

• Raised intraorbital pressure compromises optic nerve blood supply and extraocular muscle function

Key Features

• Proptosis (eye pushed forward by retro-orbital swelling)
• Painful ophthalmoplegia (restricted and painful eye movements)
• Reduced visual acuity (optic nerve compromise)
• Periorbital swelling and erythema (often severe)
• Chemosis (conjunctival oedema)
• Fever and systemic illness
• Relative afferent pupillary defect (if optic nerve affected)

Red Flags

• Reduced visual acuity or colour vision (optic nerve compromise)
• RAPD (indicates optic neuropathy)
• Complete ophthalmoplegia
• Bilateral orbital cellulitis (suggests cavernous sinus thrombosis)
• Signs of meningism (headache, neck stiffness, photophobia)
• Deterioration despite 24-48 hours of IV antibiotics (abscess likely)
• Altered consciousness (intracranial complications)

Bedside

• Visual acuity (essential baseline, serial monitoring)
• Pupil examination (RAPD)
• Colour vision (red desaturation)
• Assessment of eye movements (painful restriction)
• Measurement of proptosis (Hertel exophthalmometer)
• Temperature and observations

Bloods

• FBC: raised WCC (neutrophilia)
• CRP/ESR: raised inflammatory markers
• Blood cultures (before antibiotics if possible)
• U&Es, LFTs: baseline

Imaging

• CT orbits and paranasal sinuses with contrast: investigation of choice
  • Identifies extent of orbital infection
  • Detects subperiosteal or orbital abscess
  • Demonstrates sinus disease
  • Ring-enhancing collection indicates abscess
• MRI orbits: superior soft tissue detail; better for intracranial complications
• CT with contrast venography: if cavernous sinus thrombosis suspected

Special Tests

• Microbiology: culture of any surgically drained abscess material
• Nasal swab may identify pathogen
• ENT assessment for concurrent sinusitis

Non-pharmacological

• Admission to hospital - all cases of orbital cellulitis require inpatient management
• Serial visual acuity monitoring (minimum 4-6 hourly)
• Head elevation to reduce orbital oedema
• ENT involvement for management of underlying sinusitis

Pharmacological

• IV antibiotics - start empirically, urgent:
  • IV co-amoxiclav 1.2g TDS (covers Gram-positives, Gram-negatives, anaerobes)
  • OR IV ceftriaxone 2g BD + IV metronidazole 500mg TDS
  • If MRSA suspected: add IV vancomycin (dosed per levels)
  • Duration: IV antibiotics until clinical improvement (typically 3-7 days), then switch to oral (total 2-3 weeks)
• Nasal decongestants and saline irrigation for associated sinusitis
• Analgesia: paracetamol and ibuprofen

Surgical

• Surgical drainage indicated for:
  • Subperiosteal or orbital abscess on CT
  • No improvement or deterioration after 24-48 hours of IV antibiotics
  • Declining visual acuity
  • Non-medial subperiosteal abscess (less likely to resolve with antibiotics alone)
• Endoscopic sinus surgery with drainage via medial orbital wall approach
• Functional endoscopic sinus surgery (FESS) for underlying sinusitis

Referral Criteria

• Emergency ophthalmology referral for all suspected orbital cellulitis
• ENT referral for sinus disease management
• Neurosurgery referral if intracranial complications (abscess, CST, meningitis)
• Paediatric referral if child affected

• With prompt treatment, >90% achieve full recovery
• Visual loss occurs in 3-11% of cases
• Intracranial complications (meningitis, brain abscess): <5% with prompt treatment
• Cavernous sinus thrombosis mortality: 20-30% historically; improving with modern treatment
• Subperiosteal abscess: medial abscesses in children <9 years may resolve with antibiotics alone in >75% of cases
• Recurrence risk is low with adequate treatment of underlying sinusitis
• Long-term sequelae: residual ophthalmoplegia, visual impairment, cosmetic deformity (rare)

Chandler Classification of Orbital Complications of Sinusitis

Distinguishing Orbital from Preseptal Cellulitis

Key Facts

Preseptal (periorbital) cellulitis is an infection of the eyelid and surrounding skin anterior to the orbital septum. It is far more common than orbital cellulitis, especially in children, and carries a much better prognosis. However, careful clinical assessment is essential to distinguish it from the sight-threatening orbital cellulitis.

Epidemiology

• Far more common than orbital cellulitis (3-5× more frequent)
• Peak incidence in children <5 years
• No significant sex preponderance
• More common in winter months (association with URTI and sinusitis)

Aetiology

• Local skin breaks: insect bites, minor trauma, impetigo, chalazion, dacryocystitis
• Extension from sinusitis (particularly ethmoid)
• Upper respiratory tract infection (especially in children)
• Post-surgical: after eyelid or periorbital surgery
• Common organisms: Staphylococcus aureus (most common), Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae type b (rare since vaccination)

Pathophysiology

• Infection involves subcutaneous tissue of the eyelid anterior to the orbital septum
• The orbital septum acts as a barrier preventing posterior spread in most cases
• Haematogenous spread can occur via valveless facial veins
• In children, the thin and incomplete orbital septum offers less protection, allowing easier posterior spread

Typical Presentation

• Unilateral eyelid swelling, erythema, and warmth
• Eyelid tenderness
• Possible low-grade fever
• Often a visible entry point (insect bite, wound, chalazion)
• May have associated conjunctivitis

Importantly Normal Findings

• Visual acuity is normal
• No proptosis
• Full, painless range of eye movements
• Normal pupil reactions (no RAPD)
• No chemosis or retrobulbar involvement

Red Flags (Suggesting Progression to Orbital Cellulitis)

• Proptosis or resistance to retropulsion
• Painful or restricted eye movements
• Reduced visual acuity or colour vision
• RAPD
• Worsening swelling despite oral antibiotics
• High fever and systemic toxicity

Bedside

• Visual acuity (should be normal)
• Pupil examination (should be normal)
• Eye movement assessment (should be full and painless)
• Temperature and observations
• Careful examination for entry wound

Bloods

• FBC: may show mild leucocytosis
• CRP: mildly elevated
• Blood cultures: if systemically unwell or child <1 year

Imaging

• CT orbits with contrast: only if clinical distinction from orbital cellulitis is unclear
  • Shows pre-septal soft tissue swelling without post-septal involvement
  • Normal extraocular muscles and orbital fat
• Not routinely required if confident clinical diagnosis of preseptal cellulitis

Special Tests

• Wound swab if obvious entry point
• Consider nasal swab in context of sinusitis

Non-pharmacological

• Warm compresses to affected eyelid
• Good eyelid hygiene
• Follow-up within 24-48 hours to ensure improvement

Pharmacological

• Mild-moderate (outpatient management):
  • Oral co-amoxiclav 625mg TDS (adults) or 25/3.1mg/kg TDS (children) for 7-10 days
  • Alternative: oral cefalexin 500mg QDS + oral metronidazole 400mg TDS
  • If penicillin allergy: oral clarithromycin 500mg BD
• Severe or not responding (inpatient management):
  • IV co-amoxiclav 1.2g TDS (adults)
  • OR IV ceftriaxone 2g OD (adults) / 50-80mg/kg OD (children)
  • Switch to oral when clinically improving, apyrexial for 24-48 hours

Surgical

• Incision and drainage of associated abscess (e.g. eyelid abscess, chalazion)
• Rarely required

Referral Criteria

• Ophthalmology referral if any signs suggestive of orbital cellulitis
• Admission criteria: child <1 year, systemically unwell, unable to adequately examine eye, not improving after 48 hours oral antibiotics
• ENT referral if associated sinusitis

• Excellent prognosis with appropriate antibiotic treatment
• >95% resolve completely with oral antibiotics
• Progression to orbital cellulitis: 5-10% (higher in young children)
• Recurrence is uncommon
• Complications (rare): orbital cellulitis, abscess formation, skin necrosis
• No long-term visual sequelae if orbital involvement is excluded

Preseptal vs Orbital Cellulitis - Summary

Admission Criteria for Preseptal Cellulitis

Key Facts

A corneal ulcer (microbial keratitis) is an infectious process involving loss of corneal epithelium with underlying stromal infiltration and necrosis. It is an ophthalmic emergency requiring prompt diagnosis and treatment to prevent corneal perforation and permanent visual loss.

Epidemiology

• Incidence: 27,000-30,000 cases per year in the UK
• Contact lens-related keratitis: 1.2 per 10,000 daily-wear soft lens users per year
• Risk increases 5-15× with overnight lens wear
• Agricultural workers at risk of fungal keratitis

Aetiology

• Bacterial (most common): Pseudomonas aeruginosa (contact lens), Staphylococcus aureus, Streptococcus pneumoniae, Moraxella
• Viral: Herpes simplex keratitis (dendritic ulcer), Herpes zoster ophthalmicus
• Fungal: Fusarium, Aspergillus (tropical, agricultural injury)
• Protozoal: Acanthamoeba (contact lens, contaminated water)
• Risk factors: contact lens wear (especially extended wear, poor hygiene), corneal trauma, dry eye, corneal surgery (LASIK), immunosuppression, topical steroid use

Pathophysiology

• Disruption of corneal epithelial barrier allows organism entry
• Microbial invasion of corneal stroma triggers inflammatory response
• Neutrophil infiltration causes stromal necrosis and ulceration
• Proteolytic enzymes (from organisms and neutrophils) cause stromal melting
• Endotoxins (Pseudomonas) cause rapid corneal destruction
• Untreated, leads to corneal perforation, endophthalmitis, and loss of eye

Typical Presentation

• Acute painful red eye (often severe)
• Photophobia
• Tearing and discharge (mucopurulent in bacterial)
• Reduced visual acuity
• Foreign body sensation
• Contact lens wearer history

Examination Findings

• White/grey corneal infiltrate with overlying epithelial defect (stains with fluorescein)
• Conjunctival injection (often marked)
• Anterior chamber reaction (cells and flare)
• Hypopyon (layered white cells in anterior chamber) in severe cases
• Lid oedema

Organism-Specific Features

• Pseudomonas: rapidly progressive, large ulcer, green-yellow mucopurulent discharge, ring infiltrate
• Acanthamoeba: severe pain disproportionate to signs, perineural infiltrates (radial keratoneuritis), ring infiltrate
• Herpes simplex: dendritic or geographic ulcer pattern, reduced corneal sensation
• Fungal: feathery margins, satellite lesions, slow progression

Red Flags

• Rapidly enlarging ulcer
• Hypopyon
• Corneal thinning or descemetocoele
• Central/paracentral location threatening visual axis
• Failed initial treatment

Bedside

• Visual acuity
• Slit lamp biomicroscopy: ulcer size, depth, location, anterior chamber activity
• Fluorescein staining: epithelial defect
• Corneal sensation testing (reduced in HSV, Acanthamoeba)

Corneal Scrape

• Corneal scrape for microscopy (Gram stain), culture (blood agar, chocolate agar, Sabouraud for fungi), and sensitivity
• Perform before starting antibiotics if specialist available within 1 hour
• Consider confocal microscopy for Acanthamoeba
• PCR for HSV, Acanthamoeba in atypical cases

Bloods

• Not routinely required
• Consider HbA1c if recurrent infections (diabetes screening)
• HIV test if atypical or recurrent

Imaging

• B-scan ultrasound if posterior segment view obscured (exclude endophthalmitis)
• Anterior segment OCT: assess ulcer depth

Non-pharmacological

• Cease contact lens wear immediately
• Frequent review (daily initially)
• Protect eye from further trauma

Pharmacological

• Bacterial keratitis (non-sight-threatening):
  • Ofloxacin 0.3% drops hourly (day and night for first 24-48 hours), then reduce frequency
  • OR Levofloxacin 0.5% drops hourly
• Bacterial keratitis (sight-threatening, large, central, hypopyon):
  • Dual fortified drops: cefuroxime 5% + gentamicin 1.5% (or tobramycin 1.5%) hourly alternating
• Acanthamoeba keratitis: polyhexamethylene biguanide (PHMB) 0.02% + propamidine isethionate 0.1% (Brolene) hourly, for months
• Fungal keratitis: natamycin 5% hourly or voriconazole 1% drops; systemic antifungals may be needed
• HSV keratitis: topical aciclovir 3% ointment 5×/day for 2 weeks
• Cyclopentolate 1% for pain relief (ciliary spasm) and to prevent posterior synechiae
• Do NOT use topical steroids without specialist input

Surgical

• Therapeutic corneal transplant (penetrating keratoplasty) for corneal perforation or non-resolving disease
• Amniotic membrane transplant for persistent epithelial defects
• Tissue adhesive (cyanoacrylate) for impending perforation

Referral Criteria

• All suspected microbial keratitis requires same-day ophthalmology assessment
• Urgent corneal specialist referral for non-responding cases, Acanthamoeba, fungal keratitis
• Emergency referral if perforation or hypopyon >1mm

• Bacterial keratitis with prompt treatment: good visual outcome in >70% of peripheral ulcers
• Central ulcers carry worse visual prognosis due to scarring in visual axis
• Pseudomonas ulcers: poor outcome in 20-30% despite treatment
• Acanthamoeba: prolonged treatment (3-6 months); visual outcome poor in 25-30%
• Fungal keratitis: often poor response, 40-50% require surgical intervention
• HSV keratitis: good prognosis for epithelial disease; stromal disease may recur and scar
• Complications: corneal scarring, perforation, endophthalmitis, phthisis bulbi

Corneal Scrape Protocol

Intensive Topical Antibiotic Regimens

Key Facts

Corneal abrasion is a superficial injury involving loss of the corneal epithelium. It is one of the most common eye injuries and causes significant pain due to the dense sensory innervation of the cornea. Most heal rapidly without sequelae.

Epidemiology

• Accounts for 10% of new eye casualty presentations
• Very common overall; exact incidence difficult to determine as many do not present
• Peak in young working-age adults
• Male predominance (occupational exposure)
• Common in contact lens wearers, children, and those with occupational exposure to foreign bodies

Aetiology

• Mechanical trauma: fingernail scratch (most common), tree branch, paper edge
• Foreign body: metallic, organic, or mineral particles
• Contact lens-related: over-wear, poor fitting, dry lens
• Occupational: grinding, welding, construction
• UV keratitis: welding flash ('arc eye'), snow blindness

Pathophysiology

• Loss of corneal epithelial cells exposes underlying nerve endings (corneal nerve plexus)
• Exposed nerve endings cause severe pain, reflex tearing, and blepharospasm
• Corneal epithelium regenerates rapidly (mitotic rate increases 5-8 fold after injury)
• Healing occurs by cell migration from limbal stem cells and adjacent epithelial cells
• Incomplete basement membrane regeneration predisposes to recurrent erosion syndrome

Typical Presentation

• Acute onset eye pain following injury
• Foreign body sensation
• Tearing (epiphora)
• Photophobia
• Blepharospasm (difficulty opening eye)
• Blurred vision (if central cornea involved)

Examination

• Visual acuity (may be mildly reduced if central)
• Fluorescein staining: bright green epithelial defect under cobalt blue light
• Examine for retained foreign body (evert upper lid)
• Note size, shape, and location of abrasion
• Vertical linear abrasions suggest subtarsal foreign body

Red Flags

• High-velocity injury (risk of penetrating injury)
• White corneal infiltrate (suggests infection/microbial keratitis)
• Hypopyon (indicates keratitis)
• Irregular pupil (suggests penetrating injury)
• Reduced visual acuity not improving with pinhole
• Contact lens wearer with corneal defect (risk of microbial keratitis - treat as keratitis)

Bedside

• Visual acuity (with correction)
• Slit lamp biomicroscopy with fluorescein staining and cobalt blue light
• Evert upper eyelid to exclude subtarsal foreign body
• Pupil examination (rule out penetrating injury - teardrop pupil)
• Intraocular pressure (may be difficult due to pain; defer if penetrating injury suspected)

Bloods

• Not required for simple corneal abrasion

Imaging

• Not usually required
• CT orbits if penetrating injury suspected (metallic intraocular foreign body)
• Do NOT perform MRI if metallic foreign body suspected

Special Tests

• Seidel test if penetrating injury suspected (fluorescein streaming indicates aqueous leak)
• Corneal sensation testing if HSV keratitis differential

Non-pharmacological

• Reassurance that most heal within 24-72 hours
• Avoid rubbing the eye
• Eye patches are NOT recommended (no benefit, may delay healing - Cochrane review)
• Wear sunglasses for photophobia
• Avoid contact lens wear until fully healed (plus 24 hours)

Pharmacological

• Chloramphenicol 1% ointment QDS for 5 days: prophylactic antibiotic (lubricating effect)
• OR Chloramphenicol 0.5% drops QDS + ointment at bedtime
• Topical anaesthetic (oxybuprocaine 0.4%, tetracaine 1%): for examination only, NEVER prescribe for home use (delays healing, causes corneal toxicity)
• Cyclopentolate 1% single dose: for severe pain from ciliary spasm
• Oral analgesia: paracetamol 1g QDS ± ibuprofen 400mg TDS

Surgical

• Foreign body removal with slit lamp and needle/burr under topical anaesthesia
• Rust ring removal with rotary burr

Referral Criteria

• Ophthalmology referral if: large central abrasion, white infiltrate, penetrating injury suspected, not healing after 48-72 hours, contact lens-related (manage as possible keratitis)
• Recurrent erosion syndrome: ophthalmology for lubricants, anterior stromal puncture, or phototherapeutic keratectomy

• >95% of simple abrasions heal within 24-72 hours
• No residual visual deficit for peripheral abrasions
• Central corneal abrasions may leave faint scar affecting vision
• Recurrent erosion syndrome: occurs in 5-10%, especially with fingernail injuries; may recur for months to years
• UV keratitis resolves within 24-48 hours with supportive care
• Complications (rare): secondary infection, corneal scarring, recurrent erosion syndrome

Recurrent Corneal Erosion Syndrome

Key Principles of Corneal Abrasion Management

Key Facts

Dry eye disease is a multifactorial disease of the ocular surface characterised by loss of homeostasis of the tear film, leading to ocular symptoms including discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. It is one of the most common reasons for ophthalmology and optometry consultations.

Epidemiology

• Prevalence: 5-30% depending on definition and population studied
• More common in females (1.5-2× risk) and postmenopausal women
• Prevalence increases significantly with age (>50 years)
• Screen time and environmental factors contribute to rising prevalence

Aetiology

• Evaporative dry eye (most common, >85%): meibomian gland dysfunction, blepharitis, reduced blink rate (screen use), environmental (low humidity, air conditioning)
• Aqueous-deficient dry eye: Sjögren syndrome (primary or secondary), lacrimal gland infiltration, age-related gland atrophy
• Medications: antihistamines, tricyclic antidepressants, beta-blockers, diuretics, oral contraceptives, isotretinoin
• Systemic disease: rheumatoid arthritis, SLE, sarcoidosis, thyroid eye disease, graft-versus-host disease
• Iatrogenic: LASIK, cataract surgery, contact lens wear, radiation

Pathophysiology

• Tear film has three layers: lipid (meibomian glands), aqueous (lacrimal gland), and mucin (goblet cells)
• Loss of any component leads to tear film instability
• Hyperosmolarity of tears is the central mechanism driving ocular surface inflammation
• Inflammatory cascade (IL-1, TNF-α, MMP-9) damages epithelial cells and goblet cells

Symptoms

• Gritty, sandy, foreign body sensation
• Burning or stinging
• Paradoxical tearing (reflex tearing due to ocular surface irritation)
• Photophobia
• Blurred vision (fluctuating, improves with blinking)
• Tired eyes, difficulty with prolonged reading/screen use
• Symptoms worse in dry environments, with air conditioning, or wind

Examination Findings

• Reduced tear meniscus height
• Conjunctival hyperaemia
• Punctate corneal staining with fluorescein
• Meibomian gland dysfunction: capped or blocked gland orifices, frothy tears, lid margin irregularity
• Blepharitis: crusting, collarettes

Red Flags

• Unilateral dry eye (consider lacrimal gland tumour, nerve palsy)
• Associated with xerostomia and parotid swelling (Sjögren syndrome)
• Filamentary keratitis (severe disease)
• Corneal ulceration or perforation (severe untreated disease)
• Young patient with severe disease (investigate for Sjögren syndrome)

Bedside

• Schirmer test: filter paper in lower fornix for 5 minutes
  • Normal: >15mm; Dry eye: <10mm; Severe: <5mm
• Tear break-up time (TBUT): time for first dry spot after blink
  • Normal: >10 seconds; Abnormal: <10 seconds
• Fluorescein staining: punctate epithelial erosions
• Meibomian gland expression assessment
• Lissamine green staining: conjunctival damage

Bloods

• Anti-Ro (SSA) and anti-La (SSB) antibodies: if Sjögren syndrome suspected
• ANA, rheumatoid factor
• ESR, CRP
• Immunoglobulins

Imaging

• Meibography: infrared imaging of meibomian gland structure
• USS parotid glands if Sjögren syndrome suspected

Special Tests

• OSDI questionnaire (Ocular Surface Disease Index): validated symptom scoring
• Tear osmolarity measurement (>308 mOsm/L = abnormal)
• MMP-9 point-of-care testing (InflammaDry)
• Labial salivary gland biopsy: focal lymphocytic sialadenitis (Sjögren syndrome)

Non-pharmacological

• Lid hygiene: warm compresses (10 minutes BD) + lid massage for meibomian gland dysfunction
• Environmental modification: humidifier, reduce screen time, take regular breaks (20-20-20 rule)
• Blink exercises
• Omega-3 fatty acid supplementation (evidence mixed; DREAM trial showed no benefit over placebo)
• Moisture chamber glasses

Pharmacological

• Step 1: Artificial tears (hypromellose 0.3% QDS, carbomer 980 gel PRN, sodium hyaluronate 0.1-0.2%)
  • Preservative-free formulations preferred for frequent use (>4× daily)
• Step 2: Topical anti-inflammatory - ciclosporin 0.1% (Ikervis) OD at bedtime (NICE TA369 for severe dry eye)
  • Lifitegrast 5% (Xiidra) - available in some settings
• Step 3: Short courses of topical corticosteroids (fluorometholone 0.1% or loteprednol 0.5%) under specialist supervision
• Oral tetracyclines (doxycycline 50-100mg OD for 3 months) for meibomian gland dysfunction (anti-inflammatory, not antimicrobial at this dose)
• Oral pilocarpine 5mg TDS for Sjögren-related aqueous deficiency

Surgical

• Punctal plugs: silicone or collagen plugs to reduce tear drainage (for aqueous deficiency)
• Punctal cautery for permanent occlusion
• Intense pulsed light (IPL) therapy for meibomian gland dysfunction
• Amniotic membrane transplant for severe ocular surface disease
• Tarsorrhaphy for exposure keratopathy

Referral Criteria

• Ophthalmology referral if not responding to first-line artificial tears after 4-6 weeks
• Rheumatology referral if Sjögren syndrome suspected
• Urgent referral if corneal complications (ulceration, thinning)

• Dry eye disease is typically a chronic condition requiring long-term management
• Mild-moderate disease: well controlled with artificial tears in most patients
• Severe disease: significant impact on quality of life; may require combination therapy
• Sjögren-related dry eye tends to be more severe and progressive
• Sight-threatening complications (corneal ulceration, perforation) are rare with appropriate treatment
• Meibomian gland dysfunction may improve with consistent lid hygiene
• Quality of life impact comparable to moderate-severe angina (studies)

TFOS DEWS II Severity Grading

Key Medications Causing Dry Eye

Key Facts

Blepharitis is a chronic bilateral inflammatory condition affecting the eyelid margins. It is extremely common and often coexists with dry eye disease. Management focuses on long-term lid hygiene to control symptoms rather than cure.

Epidemiology

• One of the most common ocular conditions
• Affects all age groups but more common with increasing age
• Equal sex distribution
• Present in 37-47% of patients attending ophthalmology clinics
• Often underdiagnosed in primary care

Aetiology

• Anterior blepharitis:
  • Staphylococcal: chronic low-grade Staphylococcus aureus or S. epidermidis infection at lash base
  • Seborrhoeic: associated with seborrhoeic dermatitis, Malassezia overgrowth
• Posterior blepharitis (meibomian gland dysfunction):
  • Altered meibomian gland secretion (thickened, inspissated meibum)
  • Associated with acne rosacea
• Demodex blepharitis: Demodex folliculorum or D. brevis mite infestation of lash follicles
• Mixed forms are very common

Pathophysiology

• Bacterial colonisation produces exotoxins and enzymes causing lid margin inflammation
• Altered meibomian secretion leads to tear film lipid layer instability
• Chronic inflammation damages lid margin architecture, meibomian gland orifices, and lash follicles
• Bacterial lipases break down meibum into free fatty acids, which are directly irritating to the ocular surface
• Results in secondary tear film instability and evaporative dry eye

Anterior Blepharitis

• Crusting at the base of eyelashes (collarettes in staphylococcal, greasy scales in seborrhoeic)
• Lid margin erythema and swelling
• Lash loss (madarosis) or misdirection (trichiasis) in chronic cases
• Itching and burning

Posterior Blepharitis (MGD)

• Lid margin irregularity and telangiectasia
• Capped or blocked meibomian gland orifices
• Frothy, foamy tear film
• Expression yields thickened, turbid, or toothpaste-like meibum

Associated Features

• Dry eye symptoms (gritty, burning, tearing)
• Recurrent styes (hordeolum) or chalazia
• Marginal keratitis (peripheral corneal infiltrates)
• Seborrhoeic dermatitis of face and scalp
• Acne rosacea

Red Flags

• Unilateral blepharitis (consider sebaceous gland carcinoma masquerading as chalazion)
• Madarosis (lash loss) with mass lesion (malignancy)
• Recurrent chalazion in same location (biopsy to exclude malignancy)
• Corneal involvement (keratitis, ulceration)

Bedside

• Slit lamp biomicroscopy: lid margin assessment, meibomian gland expression, corneal staining
• Visual acuity (should be normal unless corneal involvement)
• Classification: anterior vs posterior vs mixed

Bloods

• Not routinely required
• Consider screening for rosacea-associated conditions

Imaging

• Meibography if available (infrared imaging of gland structure)

Special Tests

• Epilated lash microscopy: Demodex mites if suspected
• Lid margin biopsy: if malignancy suspected (unilateral, recurrent chalazion, madarosis)
• Tear film assessment (Schirmer, TBUT) for coexisting dry eye

Non-pharmacological

• Lid hygiene is the cornerstone of management (life-long):
  1. Warm compresses: warm flannel or heated eye mask for 5-10 minutes BD (melts meibum)
  2. Lid massage: firm downward strokes on upper lid, upward on lower lid to express meibomian glands
  3. Lid scrubs: diluted baby shampoo or commercial lid wipes (Blephaclean, Systane lid wipes) along lash base
• Artificial tears for associated dry eye symptoms

Pharmacological

• Acute exacerbation: topical chloramphenicol 1% ointment to lid margins at bedtime for 2-4 weeks
• Posterior blepharitis/MGD refractory to lid hygiene:
  • Oral doxycycline 50-100mg OD for 6-12 weeks (anti-inflammatory properties)
  • Alternative: oral azithromycin 500mg OD for 3 days, repeat monthly for 3 months
• Demodex blepharitis: tea tree oil-based lid scrubs (Cliradex), or topical ivermectin
• Topical azithromycin 1% drops BD for 2 weeks then OD for 4 weeks (posterior blepharitis)
• Short course topical steroid (fluorometholone 0.1%) for acute marginal keratitis

Surgical

• Incision and curettage of chalazion if persistent (>6 weeks)
• Intraorbital steroid injection (triamcinolone) for chalazion (alternative to surgery)
• IPL (intense pulsed light) therapy for meibomian gland dysfunction
• LipiFlow thermal pulsation device

Referral Criteria

• Ophthalmology referral if: corneal involvement, recurrent chalazion (biopsy to exclude malignancy), refractory to lid hygiene and oral antibiotics, suspected malignancy
• Most blepharitis can be managed in primary care

• Chronic condition - complete cure is uncommon but symptoms can be well controlled with ongoing lid hygiene
• Most patients achieve satisfactory symptom control with consistent treatment
• Complications: chalazion (most common), stye, marginal keratitis, corneal scarring (rare), trichiasis, madarosis
• Meibomian gland dropout (atrophy) may occur with long-standing disease and is irreversible
• Associated dry eye disease may require independent treatment
• Recurrence is the norm if lid hygiene is discontinued

Comparison of Blepharitis Types

Chalazion vs Hordeolum (Stye)

Key Facts

Strabismus (squint) is a misalignment of the visual axes where the eyes do not point in the same direction. Amblyopia (lazy eye) is reduced visual acuity in one or both eyes due to abnormal visual development in childhood, not correctable with spectacles alone. Early detection and treatment during the critical period of visual development are essential.

Epidemiology

• Strabismus: affects 2-5% of children
• Amblyopia: affects 2-3% of children
• Esotropia (convergent squint) is the most common type in childhood
• Amblyopia is the most common cause of monocular visual impairment in children
• Family history increases risk (first-degree relative with strabismus: 3-5× risk)

Aetiology

• Concomitant (non-paralytic) strabismus: most common in children
  • Infantile esotropia: onset before 6 months
  • Accommodative esotropia: associated with hypermetropia, onset 2-3 years
  • Intermittent exotropia
• Incomitant (paralytic) strabismus: cranial nerve palsy (III, IV, VI), trauma, raised ICP
• Amblyopia causes: strabismus (most common), anisometropia (different refractive error between eyes), stimulus deprivation (cataract, ptosis)
• Risk factors: prematurity, family history, Down syndrome, cerebral palsy

Pathophysiology

• During the critical period (birth to 7-8 years), the visual cortex requires equal, clear, aligned input from both eyes
• In strabismus, the deviated eye sends a different image, causing diplopia and confusion
• The developing brain suppresses the image from the deviated eye to eliminate diplopia
• Chronic suppression during the critical period leads to amblyopia - failure of normal cortical development for that eye
• After the critical period, cortical plasticity diminishes and amblyopia becomes increasingly difficult to reverse

Strabismus

• Visible misalignment of the eyes (may be constant or intermittent)
• Head tilt or face turn (compensatory posture)
• Closing one eye in bright light (intermittent exotropia)
• Diplopia (in acquired strabismus; children typically suppress)
• Family may notice deviation in photographs (corneal reflections asymmetric)

Amblyopia

• Reduced visual acuity in one eye not correctable with spectacles
• Often asymptomatic - detected on screening
• Child may not be aware of monocular visual deficit
• May have associated strabismus

Types of Strabismus

• Esotropia: inward deviation (convergent squint)
• Exotropia: outward deviation (divergent squint)
• Hypertropia: upward deviation
• Hypotropia: downward deviation

Red Flags

• Absent or white red reflex (leukocoria) - retinoblastoma until proven otherwise
• New-onset squint after 6 months of age
• Sudden-onset diplopia (cranial nerve palsy - raised ICP, aneurysm)
• Acquired squint with headache and vomiting (posterior fossa tumour)
• Any squint in a child with proptosis or periorbital swelling

Bedside

• Visual acuity (age-appropriate: Kay pictures, Sheridan-Gardiner, LogMAR, Snellen)
• Cover test: cover-uncover (manifest squint) and alternate cover test (latent squint)
• Corneal light reflex (Hirschberg test): asymmetric corneal reflections indicate misalignment (1mm = ~7° deviation)
• Red reflex (Brückner test): asymmetric or absent red reflex
• Prism cover test: quantifies angle of deviation in prism dioptres
• Eye movements: assess in all nine positions of gaze
• Cycloplegic refraction: essential to identify refractive error (cyclopentolate 1%)

Bloods

• Not routinely required
• Anti-AChR antibodies if myasthenia gravis suspected
• Blood glucose (diabetic cranial nerve palsy)

Imaging

• MRI brain: if incomitant strabismus, new-onset palsy, or suspected intracranial pathology
• MRI orbits: if orbital pathology suspected
• USS eyes: if leukocoria/abnormal red reflex (retinoblastoma assessment)

Special Tests

• Orthoptic assessment: detailed binocular vision and ocular motility evaluation
• Fundoscopy: exclude retinal pathology
• OCT if structural abnormality suspected

Non-pharmacological

• Correct refractive error: spectacles (full cycloplegic correction); this alone resolves accommodative esotropia and may improve amblyopia
• Occlusion therapy (patching): patch the dominant eye for 2-6 hours/day to force use of amblyopic eye
  • Most effective before age 7 (PEDIG trials)
  • Duration depends on severity: mild (2 hours/day), moderate (4 hours/day), severe (6 hours/day)
• Prism glasses: for small-angle deviations or compensatory head posture

Pharmacological

• Atropine penalisation: atropine 1% drops to the dominant eye on weekends or daily (blurs near vision, forcing use of amblyopic eye)
  • Non-inferior to patching for moderate amblyopia (PEDIG ATS)
  • Better compliance than patching in some patients

Surgical

• Strabismus surgery: recession (weakening) or resection (strengthening) of extraocular muscles
  • Indications: constant strabismus not corrected by spectacles, significant deviation, cosmetic concern
  • Usually performed after maximum non-surgical treatment of amblyopia
  • Adjustable sutures in adults
• Botulinum toxin injection: to extraocular muscles as alternative or adjunct to surgery

Referral Criteria

• Urgent ophthalmology referral: absent/abnormal red reflex (2-week wait), new-onset squint >6 months of age, sudden diplopia
• Routine referral: any confirmed squint on cover testing, reduced visual acuity on screening
• Orthoptic assessment: all children with suspected squint

• Amblyopia: >70% achieve improved visual acuity with treatment started before age 7 (PEDIG trials)
• After age 10-12, amblyopia treatment is largely ineffective
• Accommodative esotropia: >60% controlled with spectacles alone
• Strabismus surgery: alignment achieved in 80-90% after first procedure; 10-20% require re-operation
• Untreated amblyopia is permanent - leads to lifelong monocular visual impairment
• Binocular vision may not be fully restored even with successful treatment if strabismus was long-standing
• Long-term patching compliance is the main determinant of treatment success

UK Vision Screening Programme

PEDIG Amblyopia Treatment Studies - Key Findings

Types of Cover Test Responses