Aging and mesopic pupil diameter in drivers.

Abstract

PURPOSE: Under mesopic conditions, to determine the aging effect on pupil diameter, visual acuity and contrast sensitivity on a large sample of adults-drivers (n=101) ranging in age from 20 to 85 years old. METHODS: The population was divided in to three age categories: group A 20-50 years (n=20); gropus B: 51-70 years (n=45); group C: 71-85 years (n=36). All observers were free from significant ocular pathology. The measurements were evaluate) in right eyes with habitual optical correction. After a 5 minutes adaptation to the high mesopic luminance level (3cd/m2), the changes due to age in mesopic pupil diameter were measured using Colvard pupillometer mod 401. The OPTEC 3500 Vision Tester (stereop Opticas Co.Inc., USA) was used to conduct test of sensitivity to contrast. The background mesopic illumination was 3+-1cd/m2. RESULTS: Under low illumination condition the pupil diameter fo young and middle age (group A) was 4.37+-0.75mm; group B was 4.16+-0.85mm and in the older subjects (group C) was 3.68+-1.04mm. Mesopic pupil diameter reduced with age significantly (P=0.01). The mesopic decimal visual acuity results were; 1.24+-0.26 (group A); 0.80 +-0.14 (group B) and 0.68+-0.15 (Group C) being the differences between groups statistically significant. Mesopic contrast sensitivity decreased significantly with age at all spatial frequencies. When the three variables results were analysed between male and female, the differences were not significant. CONCLUSIONS: In drivers under mesopic conditions, the pupil diamter, the visual acuity and the cntrast sensitivity for stationary gratings of low, medium and higher spatial frequency decreased with age.