Page 197 - AIDSBK23C

Page 197

The eye is the most common extracerebral site for toxoplasmosis. The typical clinical
manifestations of ocular toxoplasmosis include impaired visual acuity with blurred vision and
visual field defects, photophobia, and redness. Chorioretinitis may be seen on funduscopic
examination.[477] The lesions are often multifocal and bilateral. There can be moderate to
severe anterior chamber and vitreous inflammation and pigmented chorioretinal scars, but
hemorrhages are not common.[819]
Acute anterior uveitis has been reported as a reversible complication in patients receiving
the drug rifabutin used to treat Mycobacterium avium-complex (MAC) infections. Persons who
weigh more than 65 kg are at greater risk. Use of a lower dosage may help avoid this
complication.[823]
Conjunctival microvascular changes may be observed in up to 75% of HIV-infected
persons. Such lesions, best observed by slit-lamp examination, are typically asymptomatic and
include segmental vascular dilation and narrowing, microaneurysm formation, comma-shaped
vascular fragments, and sludging of the blood column. Coexistent retinal microvascular changes
are often present with CD4 lymphocyte counts below 100/µL.[819]
Keratitis, though rare, can lead to loss of vision. The most common causes are Varicella-
zoster virus and herpes simplex virus. Zoster keratitis and uveitis may progress to more severe
disseminated disease, peripheral ulcerative keratitis, and. acute retinal necrosis. The severe
complication of chronic infectious pseudodendritic keratitis is usually found just with
AIDS.[819]
Ocular syphilis is found in less than 1% of persons with HIV infection and it tends to
have more aggressive, severe, and relapsing manifestations than in immunocompetent persons.
Findings include granulomatous or nongranulomatous anterior uveitis, panuveitis, necrotizing
retinitis, optic neuritis, papillitis, chorioretinitis, vitreitis, retinal detachment, branch retinal vein
occlusion, interstitial keratitis, and scleritis. Blindness may occur.[819]
Ocular tuberculosis may occur in up to 2% of patients with HIV infection. Presenting
findings can include choroidal granulomas, subretinal abscess, panophthalmitis, and conjunctival
involvement. Patients all have pulmonary tuberculosis. Ocular involvement can occur over a
wide range of CD4 lymphocyte counts, but generally below 300/µL, and the extent of disease
does not correlate with level of immunosuppression or adequacy of antitubercular therapy.[824]
Ocular lymphoma may occur as an extension of CNS disease or choroidal involvement
from systemic disease. Most cases are of the large B cell non-Hodgkin lymphoma variety.
Funduscopic findings include confluent yellow-white retinochoroidal infiltrates, perivascular
sheathing, and retinal necrosis may occur with vitreitis and floaters.[821]
Additional infectious lesions of the orbit around the eye may be seen. HIV-infected
patients with infections at this site are likely to have a very low CD4 lymphocyte count.
Reported bacterial agents include Staphylococcus aureus, Pseudomonas aeruginosa, and
Propionibacterium acnes producing orbital cellulitis or panophthalmitis. Fungal agents include
Rhizopus and Aspergillus that can spread intracranially. Orbital involvement with Pneumocystis
jiroveci (carinii), Microsporidium species, and Toxoplasma gondii have also been
reported.[819,825]
Malignancies involving the eye can include squamous cell carcinoma (SCC) of the
conjunctiva. Characteristics of conjunctival SCC can include corneal overriding, fast growth rate
with size larger than 1 cm, changes in conjunctival color, and nasal-sided locations. Lesions may
show regression with antiretroviral therapy.[819]