Age, degraded viewing environments, and the speed of accommodation.

Subjects were 35 males in an accommodation experiment which utilized a subjective laser optometer. Seven different age groups, from average age 22-52, were measured on the time to change accommodation from a near to an infinity target. During the experiment, room illumination, time duration of reading at a near distance, and the distance of a near-reading task were varied. Results indicated that the time to accommodate from a near to infinity target varied as a function of age, room illumination, and the distance of the near-reading task. During ideal conditions, older subjects could accommodate nearly as quickly as the younger subjects; however, during degraded viewing conditions, the accommodation time for older subjects increased as much as tenfold. Time to accommodate to a distant target also increased solely as a function of time spent reading at a near distance, regardless of age. In accordance with previous reviews of aging and military pilots, it is suggested that the time to accommodate may be used as an objective measure of degraded vision as it relates to age.