Cytomegalovirus retinitis (CMV retinitis) is a serious eye infection of the retina, the light-sensing nerve layer that lines the back of the eye. It is a significant threat to people with weak immune systems, such as people with HIV and AIDS, newborns, the elderly, people undergoing chemotherapy, and recipients of organ transplants. About 20% to 30% of people with AIDS develop CMV retinitis.

Infection with cytomegalovirus, one of the herpes viruses, is extremely common and does not pose a problem for someone with a strong immune system. But when immunity is weak, the CMV can reactivate and spread to the retina through the bloodstream.

First signs of CMV retinitis are loss of peripheral vision or a blind spot that can progress to loss of central vision. Without treatment or improvement in the immune system, CMV retinitis destroys the retina and damages the optic nerve, which results in blindness.

Treatment is possible for CMV retinitis. Ganciclovir and other antiviral medicines are available, and they can be administered orally, intravenously, as an intraocular injection, and, in some cases, via a sustained-release intraocular implant.

Warning signs that should prompt an immediate examination by an ophthalmologist (Eye M.D.) are the appearance of floating spots or spider webs, flashing lights, blind spots, or blurred vision. Recurrence of CMV retinitis is common, so monthly checkups with an ophthalmologist are important.

(c) 2007 The American Academy of Ophthalmology