Abstract
Abstract: :
Purpose: Previous studies have examined the relationship between distance visual acuity (DVA) and age in adults, but there has been no similar well-controlled study including children. This study extended previous research to examine the relationship between DVA and age in children. The relationship between distance and near visual acuities in adults was also examined. Methods: In 2 separate experiments best-corrected monocular DVA was measured with Bailey-Lovie high contrast letter charts for subjects with normal ocular health over a range of ages. Credit was given for every letter read correctly. Group 1: 164 subjects aged 7-35 years; Group 2: 67 subjects aged 18-86 years. For group 2 near letter visual acuity (NLVA) scored letter-by-letter and near word visual acuity (NWVA) scored to the nearest correct word were also measured. Results: DVA improved from a mean of 0.03 logMAR (6/6-1) for subjects 7-10 years of age to -0.14 logMAR (6/4.8-2) for those aged 25 to 29 years. DVA then declined to 0.1 logMAR (6/7.5) for subjects aged 75-79 years. Parabolic functions fit both data sets well (r2 = 0.99, group 1; r2 = 0.96, group 2). There were strong correlations between DVA and both NLVA (r = 0.53) and NWVA (r = 0.67), but DVA was 0.05 logMAR better than NLVA and 0.11 logMAR better than NWVA. Conclusion: Distance visual acuity measured on Bailey-Lovie style charts should be close to 6/6 for children aged 7 years and over. DVA increases during childhood by about one line, to ∼6/4.8 between 25 and 30 years of age. There is a gradual, but small decline in VA throughout adulthood, with people aged over 75 years of age maintaining DVA of at least 6/7.5. Variations in accommodation, pupil size and spatial interaction probably explain the one line difference between distance letter and near word visual acuities.
Keywords: 620 visual acuity • 310 aging: visual performance