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[Why are AIDS patients frequently visually impaired?].

Patients with HIV infection and, above all, patients with full-blown AIDS can get a variety of ocular diseases as well as some cerebral maladies which have an influence on ocular functions. First there are hematogenous opportunistic infections of the retina or the choroid. The cytomegalovirus [CMV] retinitis was found in nearly 20% of all AIDS patients. Without treatment this disease destroys the retina completely, and the involved eye becomes blind. This can be prevented by modern therapeutic strategies in most of the cases. Other infections affecting the retina are toxoplasmosis, systemic varizella zoster or herpes simplex virus infections, syphilis or, seldom, fungal or bacterial pathogens. The choroid mainly can be infested by mycobacteria, cryptococci and pneumocystis carinii. Early detection and treatment of all inflammations are necessary. The anterior eye can be affected by a sicca syndrome and various superficial infections but also noninfectious inflammation. The anterior uvea can be involved in various opportunistic infections of the posterior eye segment. An HIV-associated isolated anterior uveitis has been described in earlier stages of the HIV infection. Treatment of mycobacterial infections with rifabutin can cause an anterior uveitis as well. 1 to 2% of HIV-infected persons suffer from a zoster ophthalmicus with more severe keratitis than it occurs in immunocompetent persons. Last but not least, there are various cerebral affections which can cause visual disturbances. So the optic nerve can be involved in various forms of retinitic or meningoencephalitic processes, of ischemic mechanisms or elevated intracranial pressure. Neuroophthalmological symptoms also include homonymous hemianopsia caused by foci of cerebral toxoplasmosis, progressive multifocal leucencephalopathy or primary intracerebral malignant lymphoma situated in the central neuron of the afferent visual pathway. A variety of oculomotor abnormalities can be caused by a great variety of cerebral disease. Moreover, there are signs of neuroretinal dysfunction in computed perimetry and in color vision or contrast sensitivity testing. Some sight threatening diseases initially can be symptomless for the patient, though they should be treated immediately in order to keep the remaining visual damage small. Thus, regular ophthalmological investigations are necessary in patients with an advanced stage of the immunodeficiency, regardless whether they have ocular complaints or not. Moreover, the patients have to be advised to attend an ophthalmologist immediately, when they notice any kind of visual disturbances or ocular symptoms.