S cone pathway sensitivity in eyes with high risk and low risk drusen characteristics

A method of measuring S cone pathway sensitivity which corrects internally for media absorption, flicker sensitivity variations, and diffuse losses in retinal sensitivity is presented. Foveal S cone pathway sensitivity was measured in elderly subjects who had no ophthalmoscopically detectable retinal abnormality other than the presence of drusen. S cone pathway sensitivity was decreased in the elderly group compared with a group of young normals. The elderly group was subdivided by drusen characteristics present in fundus photographs into a group felt to be at high risk of developing age-related macular degeneration and a group judged to be at low risk. There was a mean difference in age of 7 yr between the groups. There was a weak association between a lower S cone pathway sensitivity and the presence of high risk drusen characteristics not attributable to the age difference. Yellow flicker sensitivity better separated the high risk group from the low risk group, but this was attributable to the mean difference in age between the groups. The limited usefulness of the drusen risk classification in assessing the likelihood of developing severe age-related macular degeneration highlights the need for following a group of drusen patients prospectively to assess the true worth of S cone pathway sensitivity in this disease.