PURPOSE: To determine normative values for EOG in a group of healthy adult volunteers, according to the standard protocol recommended by the International Society for Clinical Eletrophisiology of Vision - ISCEV. METHODS: 33 volunteers aging from 18 to 55 years (mean=26.75±10.50) were included in the study. EOG was recorded by skin electrodes positioned in the external canthi of the eyes, with LED stimulus presented in a Ganzfeld dome. Subject's task was to fix the LED stimulus either straight ahead or with saccadic horizontal movements. The potential difference between the cornea and posterior pole of the eye was recorded each minute. The examination was done in 3 phases: 1- pre-adaptation; 2- dark (scotopic) and 3- light (photopic). The Arden ratio was calculated as the proportion between the maximum peak amplitude in the light phase divided by the minimum peak amplitude in the dark. RESULTS: At the scotopic phase, the minimum peak amplitude occurred between 14 and 21 minutes after the beginning of the stimulation (mean=17.82±2.11 min) and the amplitude ranged from 206 to 635 µV (mean 365.73±122.52 µV). At the photopic phase the maximun peak amplitude occurred between 27 and 34 minutes (mean=30.06±1.80 min); the amplitude ranged from 646 to 1250 µV (mean= 950.70±179.16 µV). Arden ratio ranged from 1.85 to 4.02 with a lower normal limit of 1.92 and the upper limit of 4.00. CONCLUSION: The results obtained in this study are comparable to those previously reported in the literature, with a lower normal limit of 1.92 for Arden ratio. These values will be helpful to evaluate patients with several retinal disorders. Inclusion of other age groups will provide extended normative data.
Electrooculography; Reference values; Electrophysiology; Retina; Pigment epithelium of eye
