| Popis: |
Static visual acuity has traditionally been used for characterizing visual performance in the well-illuminated environment. However, there is very little information available on the performance of the aging visual system under mesopic and mesopic/scotopic conditions. The present study has been designed to help clarify and extend previous findings in this area. Young (ages 18-25, N = 40) and old (ages 60 and above, N = 80) subjects in good ocular health were tested binocularly for distance acuity with a Bausch & Lomb Orthorater at each of six luminance levels ranging from 245 to 0.2 cd/m2. All began at the lowest level and continued at each progressively higher luminance. Preliminary results suggest (1) age-related losses in acuity at all luminance levels, (2) a systematic decline in performance over each 5-yr interval beginning at age 60, (3) 80% of those over 65 were legally blind at the lowest illumination condition, and (4) performance at the highest level is a relatively poor predictor of visual acuity at the lowest level of illumination for all subjects. |
