How good is normal visual acuity?. A study of letter acuity thresholds as a function of age.
Visual acuity levels were studied in 100 normal subjects of different ages, using a finely graduated letter chart under carefully optimized test conditions. Each line on the chart contained 10 letters of similar difficulty, arranged in random order. A statistical analysis of different response criteria showed a clear superiority of fractional criteria (e.g. 50% correct responses) over the traditional 100% correct requirement. The average difference between right and left eyes was 0.04 +/- 0.15 (decimal notation). Regression analysis of the dependence of visual acuity on age showed a monotonic rise towards the age of 25 years, and a gradual decline thereafter. The most marked decline occurred after the age of 60. Age-dependent confidence intervals were tabulated. The results indicate that minor modifications of the conventional test procedure can enhance the diagnostic potential considerably.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012684:Sensory Thresholds; D014787:Vision Tests; D014792:Visual Acuity