What is the leading cause of blindness in patients with AIDS?

Cytomegalovirus (CMV) retinitis is the leading cause of blindness in patients with AIDS due to the immunocompromised state associated with the disease. Individuals with AIDS often have a significantly weakened immune system, particularly affecting their ability to combat opportunistic infections. CMV is a common viral infection that can reactivate in these individuals, leading to severe inflammation and necrosis of the retina.

When CMV retinitis occurs, it can result in vision loss through multiple mechanisms, including retinal detachment, hemorrhage, and eventually, complete retinal necrosis if left untreated. The condition typically progresses rapidly, and if no intervention is provided, it can lead to irreversible blindness.

While other conditions like toxoplasmosis, bacterial endophthalmitis, and herpes simplex keratitis are also associated with vision loss in patients with AIDS, they do not match the prevalence and severity of vision loss caused by CMV retinitis. Toxoplasmosis is more often implicated in cerebral disease, bacterial endophthalmitis is relatively rare, and herpes simplex keratitis primarily affects the cornea rather than the retina. Therefore, CMV retinitis stands out as the most significant sight-threatening condition within this patient population.