Low contrast letter acuity in age-related maculopathy

Distance low contrast letter acuity (LCLA) was assessed in six subjects with age-related maculopathy (ARM) and 12 subjects with normal visual function using a series of eight Regan charts ranging in contrast from 4% to 96%. Mean logMAR acuities for letters of 96% contrast were -0.205, -0.053 and 0.748 for the young control group (mean 23.3 years), the age-matched control group (mean 70.3 years) and the ARM subjects (mean 72.3 years), respectively. The LCLA function was found to be significantly better for the six in the young control group compared with the six age-matched controls (P < 0.05). The ARM subjects performed significantly poorer (P < 0.05) at each contrast level down to 20% compared with the age-matched subjects. A constant 0.8 logMAR difference was found between the LCLA function of the age-matched controls and that of the ARM subjects. These results show that, since the low contrast test charts revealed similar differences in visual acuity between the ARM and the age-matched groups, the use of low contrast letter charts do not appear to give any additional information of acuity loss.