Cytomegalovirus (CMV) retinitis is usually an opportunistic viral infection, found in individuals with low immunity. This condition results in the inflammation of the retina, and can eventually lead to blindness.
Cytomegalovirus infection commonly occurs in adults during their fourth decade of life. The retina can be affected when the virus spreads via the bloodstream . People infected with the human immunodeficiency virus (HIV) are at a higher risk of acquiring cytomegalovirus retinitis, as the former organism compromises the endothelial integrity of vasculature, and blood flow, in the retina . Retinitis may involve inflammation as well as bleeding of the retina, often in the ocular fundus. Lesions such as cotton wool spots can be visualized on the retina.
HIV further predisposes individuals to cytomegalovirus retinitis due to its immunosuppressive effects. This results in activation of latent infection after the host immunity decreases . Various conditions, such as diabetes mellitus, malignancy, and organ transplantation, impart the same effect  . Although cytomegalovirus retinitis in immunocompetent individuals is rare, cases have been reported. It has also been described in patients with systemic lupus erythematosus and other autoimmune diseases, with concomitant use of immunosuppressive drugs .
Cytomegalovirus retinitis can be asymptomatic. In symptomatic infection, patients may experience various visual disturbances, including floaters, photopsia, narrowed visual fields, blurred vision, and scotoma . They do not usually complain of red or painful eyes. Blindness can ensue within months of symptom onset. Furthermore, cytomegalovirus retinitis is often initially unilateral before becoming bilateral.
Notably, immunocompromised children do not seem to have increased susceptibility to this disease . Cytomegalovirus retinitis can also be congenital, occurring in 25% of babies already exhibiting other features of CMV infection, and does not usually worsen after birth.
The ophthalmologic examination is the diagnostic procedure employed. This involves dilating the pupils to visualize internal ocular structures through ophthalmoscopy.
CMV infection can be detected through biochemical analysis of blood and urine samples. Furthermore, a biopsy would reveal viral organisms in the tissue, however, this is not a routine procedure.
It is good practice to screen all patients at risk of cytomegalovirus retinitis, including those that lack symptoms, because early stage diagnosis and treatment are uncomplicated, and in addition, a significant proportion of individuals are asymptomatic at the time of diagnosis. Furthermore, intervention prevents blindness, which is a highly debilitating sequela of cytomegalovirus retinitis. Screening via testing visual acuity of patients using a Snellen chart is insufficient, as only a small portion of the retina, the fovea, is assessed in this way. The use of questionnaires specifically tailored to detect or elicit signs and symptoms of cytomegalovirus retinitis can be a more effective screening tool.
HIV patients have a higher risk of cytomegalovirus retinitis, and it is reported that the latter is the most frequently encountered opportunistic viral infection in the above group, especially when CD4 (cluster of differentiation 4) cell count is extremely low, that is, less than 50 per cubic millimeter . Immunocompetent individuals, especially those who have received steroid injections, make up the minority of cytomegalovirus retinitis patients  .