Ophthalmology – HIV/AIDS-Related Retinopathies

Basics

Description

Ocular disease is common in patients with advanced human immunodeficiency virus (HIV) infection. The two classic retinal manifestations are:

• HIV microvasculopathy (HIV retinopathy) — the most common retinal manifestation.
• Cytomegalovirus (CMV) retinitis — the most important opportunistic retinal infection and a potentially devastating cause of blindness.

Other ocular manifestations include toxoplasma retinochoroiditis, syphilitic retinitis, acute retinal necrosis (ARN), progressive outer retinal necrosis (PORN), cryptococcosis, intraocular lymphoma, Kaposi sarcoma, and ocular surface squamous neoplasia.

CMV retinitis is a full-thickness necrotizing retinal infection. Progressive retinal necrosis can result in retinal breaks and rhegmatogenous retinal detachment.

Modern antiretroviral therapy (ART) has dramatically reduced the incidence of CMV retinitis and other opportunistic ocular infections.

Epidemiology

Before effective combination ART, CMV retinitis occurred in approximately 25–40% of patients with AIDS during their lifetime.

Its incidence has fallen dramatically in the ART era.

HIV microvasculopathy was historically reported in approximately 50–60% of patients with advanced HIV infection.

CMV retinitis remains particularly important in individuals with advanced immunosuppression, including patients who are unaware of their HIV status, are untreated, or have failed ART.

Risk Factors

The major risk factor for CMV retinitis is severe immunosuppression.

The classic setting is:

CD4 count <50 cells/µL

Risk also increases with:

• High HIV viral load
• Lack of effective ART
• Poor adherence to ART
• Treatment failure or antiviral resistance
• Other causes of profound immunosuppression, including transplantation and chemotherapy

Pathophysiology

HIV Retinopathy

HIV-associated retinal microvasculopathy is thought to result from retinal microvascular injury, immune-complex deposition, endothelial dysfunction, and altered retinal perfusion.

The characteristic lesion is the cotton-wool spot, representing focal retinal nerve fiber layer ischemia.

Unlike CMV retinitis, HIV microvasculopathy does not produce progressive full-thickness retinal necrosis.

CMV Retinitis

CMV reaches the retina primarily through hematogenous dissemination during severe immunosuppression.

The virus infects retinal vascular endothelial and retinal cells, producing:

• Full-thickness retinal necrosis
• Retinal hemorrhage
• Occlusive retinal vasculitis
• Variable choroidal inflammation

Because these patients are profoundly immunosuppressed, there is often surprisingly little vitreous inflammation despite extensive retinal destruction.

Histopathologically, infected cells may contain characteristic enlarged cells with intranuclear viral inclusions.

Etiology

Cytomegalovirus is a member of the herpesvirus family.

CMV infection is extremely common in the general population and usually remains latent after primary infection.

In immunocompetent individuals, primary CMV infection is usually asymptomatic or produces a mononucleosis-like illness.

Profound impairment of cell-mediated immunity allows CMV reactivation and dissemination, including infection of the retina.

HIV Microvasculopathy

The most characteristic finding is cotton-wool spots, particularly around the posterior pole.

Other findings may include:

• Intraretinal hemorrhages
• Microaneurysms
• Telangiectatic vascular abnormalities
• Capillary nonperfusion

Cotton-wool spots generally resolve spontaneously over several weeks.

A key distinction from CMV retinitis is that HIV cotton-wool spots are small, superficial, nonprogressive lesions, whereas CMV lesions enlarge progressively without treatment.

Diagnosis

History

CMV retinitis may be asymptomatic, particularly when disease begins in the peripheral retina.

Symptoms include:

• Floaters
• Blurred or decreased vision
• Photopsias
• Scotomas
• Peripheral visual-field loss

Central disease involving the macula or optic nerve can cause profound visual loss.

Because peripheral CMV retinitis can remain asymptomatic, patients with advanced immunosuppression require a high index of suspicion.

Physical Examination

A complete dilated retinal examination is essential.

Classic CMV retinitis consists of yellow-white areas of retinal whitening and necrosis associated with variable retinal hemorrhage.

The disease characteristically progresses along retinal vascular arcades.

The advancing edge of a lesion is the most active component.

Because of severe immunosuppression, vitritis is typically mild or absent.

Classic Patterns of CMV Retinitis

Fulminant or Hemorrhagic Pattern

This consists of dense areas of retinal whitening and necrosis associated with extensive retinal hemorrhage.

The classic descriptive term is:

“Pizza pie” or “cottage cheese and ketchup” retinopathy.

Granular Pattern

This is characterized by granular peripheral retinal whitening with relatively little hemorrhage.

It may appear less dramatic but remains progressive without treatment.

Frosted-Branch Angiitis

Marked translucent white sheathing of retinal vessels produces the appearance of frost-covered tree branches.

This represents severe retinal vasculitis and may occur with CMV infection.

CMV Retinitis vs HIV Cotton-Wool Spots

This distinction is clinically important.

HIV cotton-wool spots are generally small, superficial, and nonprogressive and resolve spontaneously.

CMV lesions are usually larger, deeper, associated with retinal necrosis and/or hemorrhage, and progressively enlarge over days to weeks if untreated.

A suspicious retinal whitening lesion in a severely immunocompromised patient should therefore be followed closely or investigated for infectious retinitis.

Diagnostic Tests

Laboratory Studies

Important systemic investigations include:

CD4 T-cell count and plasma HIV viral load.

Routine CMV antibody testing is usually unhelpful because prior CMV exposure is extremely common.

Ocular Fluid PCR

When the clinical appearance is atypical or the differential diagnosis includes other infectious retinitides, aqueous or vitreous fluid may undergo PCR testing for CMV DNA.

PCR can also test simultaneously for HSV, VZV, and Toxoplasma gondii when appropriate.

Imaging

Fundus Photography

Serial wide-field or conventional fundus photographs are extremely useful for documenting lesion borders and determining whether retinitis is progressing or responding to therapy.

Optical Coherence Tomography

OCT can document retinal structural damage and is particularly useful when the macula is involved or when complications such as cystoid macular edema or epiretinal membrane develop.

Fluorescein Angiography

Fluorescein angiography may demonstrate vascular leakage and nonperfusion but is generally not required to make the diagnosis of typical CMV retinitis.

Differential Diagnosis

Important alternatives include:

• HIV microvasculopathy/cotton-wool spots
• Toxoplasma retinochoroiditis
• Syphilitic retinitis
• Acute retinal necrosis
• Progressive outer retinal necrosis
• Intraocular lymphoma
• Other infectious or inflammatory retinitides

Progressive Outer Retinal Necrosis

PORN is another particularly severe herpetic retinitis occurring in profoundly immunocompromised patients, most often caused by varicella-zoster virus.

It typically causes rapidly progressive multifocal outer retinal whitening with relatively little hemorrhage, vasculitis, or intraocular inflammation.

Disease can progress extremely rapidly and become bilateral.

PORN carries a particularly poor visual prognosis and requires urgent aggressive antiviral therapy.

Toxoplasma Retinochoroiditis

Ocular toxoplasmosis in patients with AIDS may be unusually severe.

Unlike typical toxoplasmosis in immunocompetent individuals, lesions may be:

• Large
• Multifocal
• Bilateral
• Associated with relatively little vitritis
• Unassociated with an old chorioretinal scar

CNS toxoplasmosis should also be considered in patients with ocular disease.

Treatment

Immediate Priorities

CMV retinitis is a vision-threatening opportunistic infection requiring prompt treatment.

Management has two essential components:

anti-CMV therapy + effective systemic ART.

The choice of antiviral regimen depends on lesion location, severity, systemic disease, renal and hematologic status, previous antiviral exposure, and ability to adhere to therapy.

Valganciclovir

For many patients, oral valganciclovir is preferred because systemic treatment simultaneously treats ocular disease and protects the fellow eye and other organs from CMV dissemination.

A commonly used adult induction regimen is:

Valganciclovir 900 mg orally twice daily with food for 14–21 days

followed by maintenance therapy:

900 mg orally once daily.

Dosage must be adjusted for renal impairment.

Major adverse effects include:

• Neutropenia
• Anemia
• Thrombocytopenia
• Other bone-marrow suppression
• Renal toxicity

CBC and renal function require monitoring.

Sight-Threatening CMV Retinitis

Lesions immediately threatening the macula or optic nerve require especially rapid control.

Current NIH guidance recommends systemic therapy plus an intravitreal injection of ganciclovir or foscarnet for immediate local antiviral concentrations when lesions are immediately sight-threatening.

Systemic treatment remains necessary because an intravitreal injection treats only the injected eye and does not protect the fellow eye or prevent extraocular CMV disease.

Alternative Antiviral Therapy

Alternatives include:

Intravenous ganciclovir — useful when oral treatment cannot be used or absorption is unreliable; major toxicity is bone-marrow suppression.

Foscarnet — useful particularly when ganciclovir resistance or intolerance is suspected. Important adverse effects include nephrotoxicity and electrolyte disturbances, which can occasionally precipitate seizures.

Cidofovir has anti-CMV activity but is now used much less commonly because of substantial toxicity, particularly nephrotoxicity and ocular complications such as uveitis and hypotony.

Antiretroviral Therapy

Effective ART is fundamental.

Immune recovery markedly decreases:

• New CMV retinitis
• Progression and recurrence
• Fellow-eye involvement
• Other opportunistic infections
• Overall morbidity and mortality

ART should be coordinated with clinicians experienced in HIV management.

Maintenance Therapy

Following successful induction, maintenance anti-CMV treatment is continued until sufficient immune recovery has occurred.

Current NIH guidance allows discontinuation of maintenance therapy when CMV lesions have been treated for at least 3–6 months, are inactive, and the CD4 count has remained ≥100 cells/mm³ for at least 3–6 months in response to ART, following consultation with an ophthalmologist.

Maintenance treatment should be restarted if immune function subsequently deteriorates substantially.

Follow-Up

During active CMV retinitis, patients require frequent dilated retinal examinations to document regression of the active borders and detect new lesions.

Serial fundus photography is particularly useful.

Even after immune recovery, ophthalmologic monitoring remains important because complications can occur after the infectious retinitis becomes inactive.

Immune Recovery Uveitis

Immune recovery uveitis (IRU) is an inflammatory complication that may occur after ART restores immune function in a patient with previously treated CMV retinitis.

As the recovering immune system reacts to residual CMV antigens within the eye, patients may develop:

• Anterior uveitis
• Vitritis
• Floaters
• Decreased vision
• Cystoid macular edema
• Epiretinal membrane

Additional complications can include posterior subcapsular cataract and proliferative vitreoretinopathy.

This differs fundamentally from recurrent CMV retinitis: IRU represents inflammation associated with immune recovery rather than uncontrolled viral replication.

Retinal Detachment

CMV causes full-thickness retinal destruction.

As necrotic retina heals, it becomes thin and atrophic, predisposing to multiple retinal breaks and rhegmatogenous retinal detachment.

This was a major cause of visual loss in the pre-ART era and remains an important complication of extensive disease.

Retinal detachment requires prompt vitreoretinal evaluation and frequently surgical repair.

Prognosis

The prognosis of HIV-associated ocular disease has improved dramatically with modern ART.

Visual outcome in CMV retinitis depends heavily on:

• Location and extent of retinal involvement
• Macular or optic nerve involvement
• Speed of diagnosis and treatment
• Degree of immune suppression
• Response to ART
• Development of retinal detachment or IRU

Peripheral disease diagnosed and treated early may preserve excellent central vision.

Disease involving the macula or optic nerve can cause irreversible severe visual loss.

Complications

Major complications include:

• Permanent retinal atrophy
• Macular destruction
• Optic nerve involvement
• Retinal breaks
• Rhegmatogenous retinal detachment
• Bilateral CMV retinitis
• Immune recovery uveitis
• Cystoid macular edema
• Epiretinal membrane
• Cataract
• Proliferative vitreoretinopathy
• Permanent visual-field defects
• Severe irreversible visual loss

High-Yield Clinical Pearls

CD4 <50 cells/µL + retinal whitening/hemorrhage → strongly consider CMV retinitis.

CMV retinitis = full-thickness necrotizing retinitis with surprisingly little vitritis in a profoundly immunosuppressed patient.

Cotton-wool spots are common in HIV retinopathy but are small and nonprogressive; CMV lesions enlarge without treatment.

Macula- or optic nerve-threatening CMV → systemic therapy + intravitreal antiviral treatment.

ART is essential for long-term control.

New inflammation after immune recovery does not necessarily mean recurrent CMV—consider immune recovery uveitis.

Retinal detachment is an important late complication of CMV-induced retinal necrosis.