Interactive Computer Thresholding of Central Acuity under Conditions of Contrast and Luminance Simulating Real World Environments: Evaluation of the Effects of Aging and Optical Correction

Abstract

Purpose: The Central Vision Analyzer (CVA) is an interactive computer device that has been reported to measure functional resolution at fixation under contrast and luminance conditions and fixation times which mimic a number of vision tasks of day and evening activities. The program presents Landolt C’s that are flashed at fixation for 250 msec and tumbled 1 of 4 directions; the program thresholds for the smallest C the position of which is correctly recognized. In sequential fashion, the CVA tests 3 mesopic environments (98% Michelson Contrast, MC, against a background of 1.6 cd/m2, 25% MC against 5 cd/m2, then 50% MC against 1.6 cd/m2) and 3 glare environments (98%, 10% and 8% MC, all against a background of 220 cd/m2). This report evaluates the impact of aging and optical correction method on the resolution acuity measured in normal eyes.

Methods: The visual acuities measured in normal eyes with the CVA were compared among three age groups: 18-30, 31-50 and 51-65. Comparisons were made between the three age groups in emmetropic eyes and myopic or hyperopic eyes tested with both contact lens and spectacle correction.

Results: In emmetropic eyes, a significant decline was found with aging in both the 25% and 50% MC mesopic modules with a borderline significant change in the 98% MC mesopic module (but greater than the test-retest reliability) while a significant improvement was observed with aging among the myopic eyes, approximately 0.15 logMAR. In both myopic and hyperopic eyes, a small decline in vision of 0.10 to 0.12 logMAR was observed with aging when corrected with contact lenses while with spectacles, visual acuity remained approximately stable, with both corrections producing a similar acuity in the oldest age group.

Conclusions: This study demonstrates changes in the vision measured in real world environments that is associated with aging and appears in line with the reported worsening in lens optical density, retinal sensitivity, and tear film stability that occur with aging. Whether the effects continue to worsen beyond age 65 or change in alternative ways with pathologies associated with aging, remain to be studied.