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AIDS---Ocular involvement

Author: doctorgirl78, Posted on Thursday, September 25 @ 16:11:42 IST by RxPG  

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Ophthalmology

ACQUIRED IMMUNE DEFICIENCY SYNDROME (AIDS)

SIGNS AND SYMPTOMS

AIDS is a multi-system disorder of opportunistic infections caused by the human immunodeficiency virus (HIV). This disorder is transmitted via contaminated bodily fluids, often of a sexual nature. AIDS is most common among young or middle-aged males, and is also encountered more frequently in socioeconomically depressed populations. However, AIDS respects no age, sexual, social, cultural or racial boundaries. Patients with HIV infection are usually clinically asymptomatic during the early course of infection, which may vary in length from months to years. Some patients are diagnosed with HIV infection long before the clinical manifestations appear, while others may not be aware of the infection until full-blown AIDS has ensued.



There are numerous ocular manifestations associated with AIDS, but all may be ascribed to one of four major categories:

noninfectious associated eye disease
opportunistic ocular infections
neoplasms
neuro-ophthalmic manifestations


The hallmark finding of noninfectious disease associated with AIDS is retinal cotton-wool spots. These asymptomatic lesions may be associated with other indicators of AIDS-related microvasculopathy, including retinal hemorrhages and capillary dropout. Other noninfectious complications include microvascular conjunctival alterations (e.g., capillary dilatation, irregular vessel caliber and microaneurysms), keratitis sicca, and lenticular changes.

AIDS patients may present with opportunistic ocular infections in both the anterior and posterior segments. Eyelid manifestations include molluscum contagiousum and herpes zoster ophthalmicus. Secondary corneal infections may involve rarer etiologic agents such as HSV and Candida. Most often, however, secondary ocular infections occur in the retina and choroid.

The most common opportunistic retinal infection in AIDS patients is cytomegalovirus (CMV). The classic presentation of CMV retinitis in patients with AIDS is a grossly hemorrhagic exudative retina, usually with a mild overlying vitritis (sometimes referred to as “pizza fundus”). In some cases, CMV retinitis presents as an isolated area of whitening without hemorrhage, which may be confused with a cotton wool spot. Other notable posterior segment infections in AIDS include progressive outer retinal necrosis (PORN), toxoplasmosis, histoplasmosis, and Candida choroiditis.

Malignancies associated with AIDS include Kaposi’s sarcoma (KS) and, to a lesser degree, non-Hodgkin’s lymphoma. Ocular KS may affect the eyelids, orbit or conjunctiva, and typically presents as multiple small (0.5-2cm) blue-violet to black nodules. These palpable masses are usually painless when external. Orbital lesions may induce proptosis and diplopia, and are more symptomatic. Ocular non-Hodgkin’s lymphoma typically presents as a non-tender orbital mass causing secondary ptosis, lid edema and diplopia.

Neuro-ophthalmic manifestations of AIDS may result because of primary HIV infection, secondary opportunistic infection, malignant infiltration or compression, or vascular compromise to any area of the visual or oculomotor pathways. Some of the more common manifestations include papilledema, optic neuropathies, ocular motor palsies, internuclear ophthalmoplegias, and pupillary anomalies.

PATHOPHYSIOLOGY
The HIV organism selectively invades and attacks the T-helper cells of its host at the CD-4+ receptor site. It then incorporates its own DNA into the host genome, and induces the cells to produce viral particles.

Normally, the lymphocytes recognize the foreign pathogens and initiate an appropriate immune response. Unfortunately, viral infection interrupts this activity and ultimately destroys the lymphocytes. When enough CD4+ T-lymphocytes have been depleted, the immune system becomes susceptible to opportunistic infections, and illness results. When the CD4+ T-lymphocyte count falls below 200 cells/mm3, or when other recognized opportunistic infections or secondary conditions ensue, the patient is said to have AIDS.

MANAGEMENT
Try to identify HIV infection in any individual presenting with the above findings, since AIDS has a poor survival rate and requires intensive systemic therapy to prolong life. Two commonly used serologic tests to detect HIV antibodies include the enzyme-linked immunosorbent assay (ELISA) test and the Western blot test. Most practitioners utilize the ELISA test, which is 99.5 percent specific.

Manage the various ocular conditions associated with AIDS by addressing the causative agent, although in many cases infections tend to be more virulent and difficult to treat when secondary to HIV infection. CMV retinitis, the most common ocular infection seen in AIDS patients, requires great skill in management, and therefore is probably best treated by an experienced retinologist. Two principle FDA-approved drugs used in the management of CMV include ganciclovir (Cytovene) and foscarnet (Foscavir). Experts currently suggest that combination therapy with both drugs works better than monotherapy with either one. Both intravenous and oral forms of these agents exist, as well as more recently developed intravitreal injectibles or slow-release implantation devices. Local intravitreal injectable ganciclovir and foscarnet or slow release implantation may prove helpful for patients who have an intolerance to intravenous or oral therapies, (Vitrasert) devices. Ganciclovir intravitreal implant (Vitrasert) has been seen to significantly retard the progression of CMV retinitis compared to intravenous administration of ganciclovir. A newly developed anti-viral agent Fomivirsen sodium injectable (Vitravene) has also been recently approved for the treatment of CMV retinitis.

CLINICAL PEARLS

Consider CMV retinitis and Kaposi’s sarcoma pathognomonic for HIV infection, particularly if the patient is not known to be immunocompromised in any other way. Isolated cotton wool spots, herpes zoster in young patients, atypical infections, and neuro-ophthalmic disorders without a significant history are also suspicious, and warrant further investigation and laboratory testing.

Be aware that many patients with full-blown AIDS are already under treatment with AZT (azidovudine). In these cases, gancyclovir is contraindicated due to the possibility of severe bone marrow suppression and neutropenia.



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