Contrast sensitivity and reading in subjects with age-related macular degeneration

Thirteen subjects with age-related macular degeneration (AMD) participated in a study designed to investigate the predictive value of acuity and contrast sensitivity for reading. Compared with the normally sighted individuals, the spatial contrast sensitivity of all these AMD subjects was markedly reduced, particularly at the higher spatial frequencies. The difference was smaller at frequencies below 1 c/deg. For about half the subjects, maximum monocular contrast sensitivity was better than or equal to binocular sensitivity, indicating binocular inhibition or failure of summation. For the 11 subjects who were able to read at a luminance of 40cd/m², reading speed was correlated with various measures of contrast sensitivity and acuity. Of all the visual functions tested, maximum monocular contrast sensitivity and integrated monocular contrast sensitivity showed the best correlation with monocular reading speed. Binocular contrast sensitivity functions, monocular grating acuity, and monocular letter acuity showed low and nonsignificant correlation with monocular reading speed. Practical consequences with regard to reading rehabilitation will be discussed briefly.