Posterior Uveitis
Posterior uveitis involves inflammation of the retina and/or choroid, commonly caused by toxoplasmosis, CMV, sarcoidosis, and tuberculosis, presenting with floaters, blurred vision, and potentially severe visual loss.
Key Facts
Posterior uveitis involves inflammation of the retina (retinitis), choroid (choroiditis), or both (chorioretinitis) Toxoplasmosis is the most common infective cause of posterior uveitis worldwide; classic "headlight in fog" appearance on fundoscopy CMV retinitis: occurs in immunocompromised (CD4 <50 in HIV); "pizza pie" fundus appearance; treat with ganciclovir/valganciclovir Sarcoidosis: bilateral, granulomatous; "candle-wax drippings" (periphlebitis); elevated ACE, bilateral hilar lymphadenopathy TB choroiditis: choroidal tubercles; consider in patients from endemic areas or with risk factors Presents with floaters, blurred vision, and painless visual loss (unlike anterior uveitis) Investigations: FBC, ESR, CRP, ACE, CXR, syphilis serology, QuantiFERON, toxoplasma serology, HIV test Treatment depends on cause: antimicrobials for infection; immunosuppression for non-infectious causes
Overview
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
- Retinal/choroidal inflammation → tissue oedema → photoreceptor damage → visual loss
- 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
Clinical Presentation
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)
Differential Diagnosis
| Diagnosis | Key Features | Investigation |
|---|---|---|
| Toxoplasmosis | Focal retinitis near old scar, vitritis | Toxoplasma IgG/IgM, clinical |
| CMV retinitis | Immunocompromised, haemorrhagic necrosis | CD4 count, CMV PCR (aqueous) |
| Sarcoidosis | Bilateral, periphlebitis, hilar lymphadenopathy | ACE, CXR, biopsy |
| TB | Choroidal tubercles, risk factors | QuantiFERON, CXR |
| Syphilis | Great imitator; any pattern of uveitis | Syphilis serology |
| Intraocular lymphoma | Chronic vitritis, poor response to steroids | Vitreous biopsy, cytology |
Diagnosis / Investigation
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
Management
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
Prognosis
- 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
Other Relevant Information
Key Fundoscopic Appearances in Posterior Uveitis
| Cause | Appearance |
|---|---|
| Toxoplasmosis | Focal white retinitis near old pigmented scar; "headlight in fog" |
| CMV | Haemorrhagic retinal necrosis; "pizza pie" or "cottage cheese and ketchup" |
| Sarcoidosis | Periphlebitis ("candle-wax drippings"); choroidal granulomas |
| TB | Choroidal tubercles; serpiginous-like choroiditis |
| ARN (acute retinal necrosis) | Peripheral retinal necrosis; HSV/VZV |
| Birdshot | Cream-coloured lesions scattered like birdshot; HLA-A29 |