Page 196 - AIDSBK23C

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patients with immune recovery, the incidence of retinal detachment in at least one eye is over
100-fold greater than that in the general population [820,821]
However, patients receiving antiretroviral therapy resulting in a rise in CD4 lymphocyte
counts may experience spontaneous healing of CMV retinitis lesions, even in the absence of anti-
cytomegalovirus therapy. Such patients may also have atypical features of ocular CMV
infection, including moderate to severe anterior chamber or vitreous inflammation.[819] The
immune reconstitution inflammatory syndrome (IRIS) that accompanies successful antiretroviral
therapy occurs in about 3% of patients as a result of partial reconstitution of the immune system
sufficient to allow an inflammatory reaction to develop against a previously subclinical CMV
infection. Clinical features include decreased visual acuity and floaters. Polymorphisms in the
IL-10R1 gene are associated with risk for development of CMV retinitis. An amino acid
substitution rs2229114 in the IL-10R1 gene appears protective against CMV retinitis.[285,821]
Cytomegalovirus can be confirmed at autopsy by finding characteristic inclusion bodies
in the choroid. About half of CMV retinitis cases have an acute inflammatory reaction.
Treatment and/or long survival may lead to extensive degeneration with loss of cells of the
retina. About 20% of AIDS patients with CMV retinitis may eventually develop retinal
detachment. Persons receiving antiretroviral therapy are less likely to develop retinal
detachment.[820,821]
Clinically, CMV retinitis can produce loss of vision and on occasion severe discomfort,
but symptomatology is lessened by antiviral therapy with ganciclovir or foscarnet. Cidofovir
therapy can also be used and has the advantage of longer dosing intervals. The newest agents
include formiversen and valganciclovir.[821] Initial response rates are high but recurrence of
CMV retinitis can occur, so the goal of therapy is to delay progression of disease.[417]
Ganciclovir implants have been employed for ongoing therapy, and pathologic findings
associated with this therapy include fibrous ingrowth from the implant site into the vitreous,
vitreous hemorrhage, and foreign body giant cell reactions to suture material, but these are
benign occurrences because of limited extension.[822] When funduscopic examination reveals
evidence for CMV and therapy is instituted, there is a decreased likelihood that the patient will
have nonocular organ involvement by CMV.[820]
The second most common cause for retinitis in AIDS is infection with the Varicella-
zoster virus (VZV), seen in 1 to 4% of HIV-infected persons, typically when there is
involvement of the ophthalmic division of the trigeminal nerve. VSV can produce several
patterns of ocular involvement. Acute retinal necrosis produces sharply demarcated
inflammation of the anterior uveal tract and peripheral circular necrosis with centripetal
progression toward the posterior pole associated with vitreitis, occlusive periarteritis, and
confluent full thickness retinal necrosis. This process leads to deceased visual acuity, ocular
pain, neuritis, arteritis, phlebitis, scotomata, and narrowing of the visual field. There can be
eventual blindness from optic atrophy. Progressive outer retinal necrosis, or rapidly progressive
herpetic retinal necrosis, occurs most often with advanced AIDS and is often bilateral with
involvement of deeper retinal layers, macular involvement, retinal detachment, and outer retinal
opacification. This condition can be treated with ganciclovir and foscarnet.[462,821]
A retinal microvasculopathy may be observed in over half of AIDS cases. It is non-
infectious, but the cause is unknown. Findings include cotton wool spots, intraretinal
hemorrhages, and retinal microaneurysms. This condition is more likely to occur when the CD4
count drops below 100/µL. This condition is usually asymptomatic and transient.[819]