Differentiation of neovascular maculopathies by nonphotic electrooculogram responses

Four kinds of electrooculographic (EOG) responses for the retinal pigment epithelium (RPE) were studied to assess RPE integrity in neovascular macular diseases. In 20 eyes with age-related macular degeneration (ARMD), 13 fellow eyes of ARMD patients, eight eyes with central exudative chorioretinopathy (CECR), and seven unaffected eyes of CECR patients, we evaluated the light peak/dark trough ratio, and the hyperosmolarity, Diamox, and bicarbonate responses. We found no abnormalities in any ARMD eyes or fellow eyes of ARMD patients. In both the CECR eyes and unaffected eyes of CECR patients, however, the Diamox response was subnormal whereas the other three EOG responses remained normal. There was no significant difference in Diamox response between the CECR eyes and unaffected eyes of CECR patients. The selective deterioration of the Diamox response in CECR, but not in ARMD, can serve as a new index for differentiating between these similar conditions.