P 454 Comparative study of the ERG on- and off-response spectral sensitivity: Influence of GABAergic system

Purpose : A new method of calibration of the displacement of the cornea1 reflex in relation to the angular deviation was carried out on a population of normal subjects. Methods : The position of the cornea1 reflex was studied in 15 normal adult subjects, emmetropic and orthophoric. Each eye, photographed individually, was situated perpendicularly at the zero of a tangential scale. Slides taken in 17 positions of gaze permitted measurement of the distance of the cornea1 reflex from the nasal and temporal limbus. Calculation of the displacement of the reflex in relation to the primary position was expressed as percentage deviation of the reflex. Results : The regressions made between the angular deviation expressed in dioptres and the percentage deviation of the reflex demonstrated the existence of a linear relation. Perfect correspondence was found to exist between the right and left eyesThe calculation as a percentage, taking the cornea1 diameter into account, allowed errors in extreme positions of gaze to be minimized. Direct measurement in millimeters allowed us to find a conversion factor of 21,6 A of angular deviation per millimeter deviation of the reflex. COI’IC~UB~OIIB : The statistical results found in this study confirmed the close correlation between the position of the cornea1 reflex and the ocular deviation. One millimeter of cornea1 reflex deviation corresponds to an angular rotation of 21,6 A. COMPARATIVE STUDY OF THE ERG ONAND OFF-RESPONSE SPECTRAL SENSITIVITY: INFLUENCE OF GABAERGIC SYSTEM. KUPENOVA P. VITANOVA L. POPOVA E. MITOV' ' rT Y . Dept. Physiology, Medical Faculty, Sofia, Bulgaria