Abstract
Abstract: :
Purpose: Our goal is to investigate the relationship between anatomical abnormalities observed by Optical Coherence Tomography (OCT) and visual functional changes in individuals with ARMD at central and eccentric retinal locations, in order to determine the extent to which functional deficits may be predicted from structural changes. Methods: Five subjects with early atrophic ARM aged 50+ and 10 age–matched controls took part. A Humphrey–Zeiss OCT2 was used to take cross–sectional images from 9 predetermined retinal areas including the anatomical fovea and 5° and 10° eccentrically in four quadrants. Contrast sensitivity (CS) for 0.4 cpd static and alternating (7.5 Hz) sine–wave gratings was measured with a psychophysical method of limits. The grating area was 3°, had a vignette envelope and a cosine onset and offset. Presentation duration for the static and alternating gratings was 247 and 200 msecs respectively. Visual acuity was measured with computer–generated single and crowded Landolt Cs used a method of constant stimuli and presentation duration of 100 msecs. CS and VA were measured at the same retinal locations as the OCT scans. Results: Two of the 5 subjects with ARM had reduced corrected logMAR VA. There were deficits in static CS in 3 of the subjects with ARM at 5° eccentricity and in 2 subjects at 10° (95% confidence limits). Only one showed a static CS deficit at the fovea. Alternating CS and single and crowded VA were mostly within the normal range (95% confidence limits) for eccentric targets, although 3 of the subjects showed deficits in uncrowded acuity at the fovea. Two subjects with ARM showed retinal thinning at the fovea measured with the OCT, three showed retinal thinning at 5 or 10°, and one showed retinal thickening at 10°. Generally, those subjects who showed retinal thickness changes by OCT and retinal changes as observed by fundus photography also showed functional deficits. Conclusions: Subjects with early ARM showed deficits in static contrast sensitivity for low spatial frequency alternating gratings, but not for similar static gratings. These deficits were found out to 10° eccentricity. There was little evidence of increased contour interaction effects for subjects with early ARM compared to the controls. Other measures of function did not show consistent deficits. Retinal thickness changes were observed out to 10 degrees.
Keywords: age-related macular degeneration • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • contrast sensitivity