Immunosupressed. The retina is a very protected site and so inflammation is uncommon. There are a few viruses that can do so especially in the immunosupressed. There are a few autoimmune processes that attack the retina under the generic name uveitis. Some parasites can invade the retina like toxoplasmosis and histoplasmosis. If you have symptoms, floaters and vision loss, see your ophthalmologist.