A new test designed to detect an hereditary eye disease called retinitis pigmentosa (RP) is described. This condition is revealed by pigmentation in the retina, but early diagnosis is difficult because the symptoms are subtle, and since it is genetically recessive it frequently occurs in families with no history of early blindness. In many cases RP results in gradual loss of vision and eventual blindness. The test for this problem is in a developmental stage and involves electrical signals picked up from a contact lens electrode placed on the subject's cornea. The responses of the eye to brief flashes of light may thus be recorded and charted and compared to those of subjects with normal vision. (JD)