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 |