Effect of light filters on contrast sensitivity function in normal and retinal degeneration subjects

Contrast sensitivity functions were measured with five light filters and without a filter, in the presence of a glare source, in 12 retinal degeneration subjects and 9 normal subjects. The light filters included yellow-tinted, CPF 527, NoIR 111, 0.6 neutral density and sunglasses with a 95% UV filter. Retinal degeneration subjects showed a mild improvement in contrast sensitivity at the higher spatial frequencies and maintained mean log contrast sensitivity with light filters which reduced photopic light transmission up to 75%. Normal subjects exhibited a systematic decrease of contrast sensitivity at higher spatial frequencies with all light filters and overall mean log contrast sensitivity was significantly correlated (r = 0.86, P < 0.025) with photopic light transmission of the filters. It is concluded that, when in the presence of a glare source, the benefits of certain light filters to retinal degeneration subjects is related to the reduction of overall photopic luminance.