Threshold and Rate of Dark Adaptation as Functions of Aǵe and Time

In order to describe one family of dark adaptation curves obtained from an age sample ranging from 16 through 89 years, a mathematical model of the form [Formula: see text] was derived. It was found that the model could be generalized. In addition it was concluded that threshold of dark adaptation as a function of time was lawfully related to chronological age. Rate of adaptation was determined by differentiating the equation at time 30 sec and time 6 min as follows: [Formula: see text] The results showed that rate of dark adaptation was a curvilinear function of age. These findings are consistent with the hypotheses that dark adaptation threshold and rate of dark adaptation depend upon basic underlying physiological processes that change with age.