Functional and ophthalmoscopic observations in human laser accident cases using scanning-laser ophthalmoscopy

摘要

Abstract: A scanning laser ophthalmoscope (SLO) equipped with an acousto- optical modulator (ACM) was used to make focal acuity and contrast sensitivity measurements in individuals with macular damage. The depth of modulation achieved by the ACM was determined by imaging the SLO raster pattern onto a Pulnix TM 745 video camera and evaluating the intensity distribution with a Big Sky BVA10 beam view analyzer. Contrast levels remained approximately constant over the entire range of SLO input raster power settings. A delta Technologies image processing system produced Landolt ring test stimuli at the center of the raster pattern. Contrast thresholds were determined at various retinal locations by having subjects fixate a specific location on a fixed grid imaged on the raster pattern. This procedure insured that the test stimuli were always imaged in the center of the raster pattern thereby avoiding peripheral variations in the raster pattern intensity distribution. Measurements of contrast sensitivity where focal test targets fell within the macular damage area demonstrated elevated contrast thresholds relative to retinal locations where focal test targets evaluated the border regions between normal and pathological retina. !4