Autoimmune retinopathy and cancer-associated retinopathy (CAR) are rare eye disorders in which autoantibodies damage the retina, causing progressive vision loss. An autoantibody is a type of protein produced by the immune system that is directed against one or more of an individual's own proteins. It is thought that in autoimmune retinopathies the autoantibodies attack proteins of the retina, therefore causing retinal disease. In CAR, the autoantibodies are thought to be generated in response to a cancerous tumor that is present in the body.
The visual loss associated with autoimmune retinopathy and CAR usually occurs over a short period of time (weeks to months) but can occur more suddenly. Visual symptoms include the following:
- Decreased central and/or peripheral vision
- Night blindness, poor color vision, sensitivity to light
- Photopsias (shimmering or flashing lights)
Although vision loss usually occurs in both eyes together, asymmetrical vision loss has been documented. In CAR, the onset of vision loss can occur before a cancer is even identified, or in contrast, months to years after a cancer has been diagnosed or treated.
Autoimmune retinopathy and CAR are difficult conditions to diagnose, both due to their variable presentations and the fact the recognition of these conditions occurred relatively recently. The ERG (electroretinogram) can help establish the diagnosis. In addition, testing for the presence of autoimmune antibodies in blood can aid in the diagnosis. Because the visual symptoms associated with autoimmune retinopathy and CAR are so similar, it is advised that all individuals suspected of having either condition undergo a thorough cancer evaluation.
Although it is known that autoimmune retinopathy and CAR are rare conditions, their exact prevalence is unknown.