Effects of luminance on contrast sensitivity in senile macular degeneration.

Patients with senile macular degeneration (SMD) often have difficulties in adapting to changing luminance levels. They may complain of problems at both high and low luminance levels, although some patients have their vision function markedly improved at high luminance levels. We examined the effect of luminance on the contrast sensitivity function in six patients with SMD and five normals of approximately the same age. The contrast sensitivity of the SMD patients compared to the control subjects was reduced at 72 cd/m2 but was comparable to that of the controls at 0.007 cd/m2. The peak of the contrast sensitivity function was moved to lower spatial frequencies at all luminances in the SMD group, and the slope of the function relating contrast sensitivity to luminance was reduced. These data suggest that adaptation mechanisms which optimize contrast detection are disrupted in SMD. Further disturbances of function might be expected in the dynamics of the adaptation process.