Viral uveitis

Herpes simplex keratitis (usually HSV1)

• Causes anterior uveitis, usually associated with keratitis
• Unilateral AAU with KPs
• Patchy iris atrophy with transillumination defects
• Glaucoma secondary to trabeculitis or inflammatory debris
• Posterior uveitis: acute retinal necrosis, occlusive vasculitis, retinal detachment
• Requires a very slow taper of topical steroid
• Consider long-term oral antiviral prophylaxis

Varicella zoster

• Vesicular rash
• Associated keratitis (superficial, disciform, stromal)
• Mild anterior uveitis
• Rarely necrotizing retinitis (ARN or PORN)
• Increased risk of uveitis if Hutchinson's sign positive
• Requires slow taper of topical steroid

Cytomegalovirus

• CMV hypertensive uveitis occurs in immunocompetent patients

• Also a leading cause of visual loss in AIDS patients (and other immunocompromised individuals)

• Anterior uveitis associated with raised IOP

  • Less likely to have iris atrophy cp. HSV and VZV
  • Treatment can be challenging: consider oral valganciclovir
    • Valganciclovir is a prodrug of ganciclovir which is available orally
    • Excellent bioavailability
    • Has superceded ganciclovir for induction and maintenance therapy

• Corneal endotheliitis

• CMV retinitis

Acute retinal necrosis

• Rare necrotizing retinitis caused by HSV1 or 2 and VZV

Clinical features

• Unilateral reduced vision, floaters
• Occlusive arteritis
• Well-demarcated, circumferential areas of full-thickness necrotizing retinitis
• Vitritis and AC activity
• Retinal detachment
• Ischaemic optic neuropathy

Tests

• AC and/or vitreous tap with PCR

Management

• Intravenous aciclovir
• Systemic corticosteroids
• Aspirin
• Barrier PRP
• Vitrectomy for RD
• Valaciclovir can be consider but carries risk of nephrotoxicity
• Intravitreal foscarnet

Progressive outer retinal necrosis

• Devastating necrotizing retinitis caused by VZV in immunocompromised patients
• Painless loss of vision
• Rapidly progressive white areas of outer retinal necrosis with minimal vasculitis, retinitis or vitritis
• Management: consider IV ganciclovir, foscarnet
• Poor prognosis (high rate of RD)

West Nile virus infection

• Single stranded RNA flavivirus causing zoonotic disease
• Transmitted via infected mosquito vector
• Diabetes is a risk factor: increases mortality
• 80% are asymptomatic
• Mild reduction in vision
• Bilateral > unilateral multifocal chorioretinitis
• Tests: WNV-specific IgM antibody
• No proven treatment, generally self-limiting

Chikungunya virus infection

• Epidemics caused by human-mosquito transmission
• Self-limiting febrile illness with arthralgia, rash, low back pain
• Anterior uveitis
• Fine KPs
• Raised IOP
• Posterior uveitis: retinitis with haemorrhages, vasculitis, optic neuritis
• Tests: raised ESR/CRP, PCR to identify virus, and serum chikungunya specific IgM
• Management: symptomatic control. NSAIDs, topical corticosteroids for uveitis

Measles, mumps, rubella, dengue, Ebola and HTLV-1 can cause uveitis

• Measles associated with subacute sclerosing panencephalitis
• HTLV-1 causes leukaemia

HIV-associated disease (see viral infections sections under Microbiology)

• HIV-1 and HIV-2: retroviruses that infect CD4 T cells

Risk factors

• Sexual intercourse
• IVDU
• Blood transfusion
• Maternal (vertical) infection

Markers of disease

• CD4 count: indicator of immunocompromise

• Viral load: indicator of risk of progression

• Histology: large eosinophilic intranuclear/intracytoplasmic inclusion bodies (‘Owl’s eye’)

Antiretroviral therapy

• Comprises at least 3 antiretroviral drugs
  • Nucleoside reverse transcriptase inhibitors
  • Protease inhibitors
  • Non-nucleoside reverse transcriptase inhibitors

Ocular disease

• Conjunctival microvasculopathy: irregular calibre vessels with corkscrew pattern

• Keratouveitis:

  • VZV keratouveitis is common (AAU, raised IOP, iris atrophy)
  • HSV keratouveitis: similar risk to general population, but more severe
  • Microsporidial keratouveitis: punctate keratopathy with follicular conjunctivitis and anterior uveitis

• Anterior uveitis: affects over half of HIV patients

  • Can be caused by therapy eg. rifabutin (anti-atypical mycobacterial) and cidofovir (anti-CMV)

• CMV retinitis

  • Associated with very low CD4 counts (<50/mm3)

  • Floaters, reduced vision, field loss

  • AC inflammation

  • Vitritis

  • Patterns of retinitis

    • Haemorrhagic retinitis with necrosis: large areas of hemorrhage against a background of whitened necrotic retina, typically along the vascular arcades
    • Granular retinitis (especially if peripheral): relatively indolent
    • Perivascular, frosted branch angiitis

  • RD

  • Optic neuropathy

Management of CMV retinitis in HIV-patients

• ART to achieve a CD4 count of above 200
• Systemic antiviral: eg. (val)ganciclovir (risk of neutropenia), foscarnet, cidofovir (risk of renal toxicity)
  • Intravitreal antivirals

Other ocular manifestations of HIV

• Toxoplasma retinochoroiditis

  • Therapy to combat pneumocystis is also toxoplasmacidal so the frequency has greatly reduced
  • More severe in HIV patients

• HIV microvasculopathy: tortuosity of retinal vessels with cotton wool spots, telangiectasia, intraretinal hemorrhages and occlusive disease

• Neuro-ophthalmic: cerebral toxoplasma, cryptococcal meningitis, neurosyphilis

• Molluscum contagiosum