QUADRANT PATTERN ERG WITH SLO STIMULATION IN NORMALS AND GLAUCOMA PATIENTS

Background: The pattern ERG (PERG) is one of the promising methods for investigation of glaucoma and may detect it at an early stage. The pu rpose of this study was to test the usefulness of the scanning laser o phthalmoscope (SLO) as a stimulator for evoking quadrant PERGs under v isual control in normal and glaucoma eyes. Methods: The helium-neon la ser of a Rodenstock SLO was used for quadrant stimulation (18 degrees X29 degrees pattern size), while an infrared laser visualized the eye' s fundus. Steady-state pattern-reversal ERGs were recorded in response to stripe patterns (8.33 Hz. 0.5 cycles/deg) in four retinal quadrant s. Corresponding visual field defects were determined with the Octopus perimeter (G1, peridata). The subjects were 28 controls and 34 glauco ma patients with visual field losses and papillometric defects. Result s: Amplitudes of nasal retinal areas (which include the blind spot) ar e smaller than those of temporal ones, and temporal lower responses ar e the largest. PERG amplitudes of all quadrants are significantly redu ced in glaucoma (sensitivity 82%, specificity 80%). The differences be tween upper and lower quadrant PERGs are correlated with the differenc es between localized visual field defects of the same areas. (r=0.46, P=0.02). Conclusions: The study demonstrates the feasibility of the SL O system for evoking localized PERG in normals and patients and shows the reduction of quadrant ERG amplitudes in glaucoma using the laser s ystem.