Posterior Uveitis

Posterior uveitis is inflammation of the choroid and retina (choroiditis, retinochoroiditis, retinitis) and retinal vasculature. It causes a large share of inflammatory visual loss, because the macula and optic nerve are exposed.

Infectious causes: toxoplasmosis (most common in immunocompetent patients), cytomegalovirus retinitis (CD4 count under 50 cells/microlitre), acute retinal necrosis (varicella zoster and herpes simplex), syphilis, tuberculosis, toxocariasis, and candida. Noninfectious causes: sarcoidosis, birdshot chorioretinopathy (HLA-A29 positive in over 95%), Vogt-Koyanagi-Harada disease, Behçet vasculitis, serpiginous choroiditis, multifocal choroiditis and sympathetic ophthalmia.

Complications: cystoid macular edema, retinal detachment, choroidal neovascularization, vitreous hemorrhage, ischemic maculopathy and optic atrophy. Infectious retinitis can destroy the retina within days.

• Floaters, painless blurring, scotomata, photopsia and nyctalopia (birdshot)
• Vitritis, focal yellow white retinal or choroidal lesions, retinal vascular sheathing, disc swelling, macular edema
• Acute retinal necrosis: peripheral confluent necrosis, arteriolitis, anterior chamber inflammation
• Cytomegalovirus: granular hemorrhagic retinitis along the arcades without vitritis
• Vogt-Koyanagi-Harada: bilateral exudative detachments with headache, tinnitus, meningism, poliosis and vitiligo
• Red flags: necrotizing retinitis, hypopyon, bilateral disease, immunosuppression

• Dilated fundus examination with wide field photographs and anterior chamber assessment.
• Optical coherence tomography, fluorescein angiography (leakage, occlusion, optic disc staining) and indocyanine green angiography (hypofluorescent choroidal spots). Fundus autofluorescence and B-scan for opaque media.
• Aqueous or vitreous PCR for herpes simplex, varicella zoster, cytomegalovirus and toxoplasma. Antibody coefficient over 3 supports local toxoplasma production.
• Systemic tests: HIV, treponemal serology and RPR, interferon gamma release assay, chest imaging, serum ACE, HLA-A29, full blood count, liver and renal function.
• Vitreous biopsy with cytology for suspected lymphoma.

Differentials: intraocular lymphoma, metastasis, retinitis pigmentosa, ocular ischemic syndrome, retinal vasculitis from systemic disease.

Acute retinal necrosis: aciclovir 10 mg/kg intravenously every 8 hours for 10 to 14 days, then valaciclovir 1 g orally three times daily for 6 to 12 weeks. Add intravitreal foscarnet 2.4 mg in 0.1 mL twice weekly. Monitor creatinine and hydrate. Prophylactic laser demarcation or vitrectomy for detachment risk.

Cytomegalovirus retinitis: valganciclovir 900 mg orally twice daily for 21 days, then 900 mg daily until CD4 count exceeds 100 cells/microlitre for 3 months. Intravitreal ganciclovir 2 mg in 0.1 mL for sight threatening lesions. Start antiretroviral therapy within 2 weeks. Monitor full blood count (neutropenia).

Noninfectious:

• Prednisolone 1 mg/kg daily orally (maximum 80 mg), tapering over at least 3 to 6 months. For Vogt-Koyanagi-Harada, intravenous methylprednisolone 1 g daily for 3 days, then oral prednisolone with a slow taper over 6 months.
• Periocular triamcinolone 40 mg or intravitreal triamcinolone 4 mg in 0.1 mL for unilateral macular edema. Dexamethasone implant 0.7 mg or fluocinolone implant 0.18 mg for chronic disease.
• Steroid sparing therapy early: methotrexate 15 to 25 mg weekly with folic acid 5 mg weekly, mycophenolate mofetil 1 g twice daily, ciclosporin 2.5 to 5 mg/kg daily in 2 divided doses, azathioprine 2 to 2.5 mg/kg daily, adalimumab 40 mg subcutaneously every 2 weeks, with monitoring of blood counts and liver enzymes.
• Choroidal neovascularization: intravitreal aflibercept 2 mg monthly for 3 doses then as needed.

Toxoplasma retinochoroiditis: trimethoprim-sulfamethoxazole 160/800 mg orally twice daily for 6 weeks, with prednisolone 0.5 to 1 mg/kg daily from 24 to 48 hours after starting treatment.

Surgery: vitrectomy for diagnosis, nonclearing hemorrhage and retinal detachment.

Review at 1 to 2 weeks, then monthly until quiescent. Counsel on adherence and on infection risk during immunosuppression.