Abstract
Abstract: :
Purpose: To investigate whether a small angle glare test in a clinical setting can produce and detect a significant decrease in contrast sensitivity with age in normal young and elderly eyes. Methods: Contrast sensitivity (CS), with and without glare, was measured in 20 subjects. The subjects were all fully corrected. CS was measured using the "Freiburg Visual Acuity & Contrast Test" (FrACT) software running on a Macintosh imac (CRT). In our set-up the software uses a 4AFC-method, and the test distance was 4 meters. Glare was induced by a Fostec DCR® II light source with a randomised fiberoptical bundle mirrored into the centre of a Landolt C test target. Full test symmetry was accomplished by using this glare set-up. The test target and the glare source subtended an angle of about 1.3° and 0.2° respectively, yielding a 0.5° glare angle. The target mean luminance was 61 cd/m2 and the illuminance at the eye was 15 lux with glare. Results: We measured 20 subjects (20 to 59 yrs) with no known eye disease. The results from the measurements were analysed seperately and also calculated as glare scores (CS without glare divided by CS with glare). CS data with and without glare produced low correlation with age, but the data showed large correlation with age when calculated as glare scores. The increase in glare score with age was about 2.5 in the tested group. The data was also compared with measurements of after cataract patients. For these patients the glare scores were about 10 to 20 times higher. Conclusions: The results indicate that this method is useful in studies of glare in normal and elderly eyes. The data also indicate a usefulness in quantifying the impact of cataract and after cataract.
Keywords: contrast sensitivity • aging: visual performance • physiological optics