The retina lines the back of the eye rather as film lines the back of a camera, and as the retina loses function parts of the vision may appear dull or may be absent. The cause of retinal malfunction is, as yet, unknown and the nature of the association between the malfunction and the inflammation has not been identified.
When we view the back of the eye, evidence of inflammation is usually evident, although the dysfunctional retina appears quite normal. The diagnosis is confirmed at the Eye Hospital by recording the electrical response of the retina to light (electroretinogram), which confirms that the visual loss is due to retinal disease rather than problems elsewhere.
The condition usually presents with flashing lights and an enlarged blind spot. The area of visual loss may spread for a period and then become stable. In the majority of patients, the retina recovers its function over a period of one to three years. However, in a small proportion there is no recovery of function and, with time, permanent damage to the retina is done