We assessed clinical utility of fast and slow oscillations (FO and SO) of the electrooculogram (EOG) in Harada disease. In 12 eyes of 4 female and 2 male subject patients aged 18 to 77 years (average: 41.8 years), FO and SO were recorded using an automated electrooculograph, the Nidek EOG-2, in the acute period before treatment and in the remission period under corticosteroid therapy. FO parameters, namely the RfFO [the average ratio in percentage of the maximum amplitude in the dark period (AD)/the minimum amplitude in the light period (AL) during FO measurement] and the dfFO (the average difference in ?V between AD and AL) were evaluated. The L/DSO (the light peak/dark trough ratio of the SO) was calculated as an SO parameter. The RfFO, dfFO and L/DSO showed low values in 7 (58.3%), 10 (83.3%) and 8 (66.7%) out of all 12 eyes in the acute period, respectively. In the remission period, values in the normal range were obtained in 12 (100%), 11 (91.7%) and 8 (66.7%) out of 12 eyes in the RfFO, dfFO and L/DSO, respectively. In mutual relation to each RfFO, dfFO and L/DSO in the acute and remission periods, all 12 eyes showed recovery values both in the RfFO and dfFO in the remission stage after systemic administration of corticosteroids, but 4 out of 12 eyes (33.3%) showed no recovery in the L/DSO. The FO may therefore well reflect the affected or ameliorated conditions in the outer layers of the retina and the choroid in Harada disease, in contrast to the SO. However, further observations are requested in more Harada disease patients
