EFFECT OF FILTERS ON DISABILITY GLARE

Disability glare is the reduction in visual performance caused by a pe ripheral glare source. We examined the effect of a long wavelength pas s (red) and a short wavelength pass (blue) filter on disability glare in the presence of varying amounts of induced wavelength dependent str ay light. Measurements were made in the absence of any filter and then repeated in the presence of the red and blue filters whose luminous t ransmission factors were equal relative to both the stimulus and the g lare source. Neither of the filters had any effect on disability glare . Filters not only reduce the amount of veiling luminance from the gla re source, but also reduce the ability to detect the stimulus. Disabil ity glare was not significantly different with the red and blue filter s, even in the presence of wavelength dependent scatter. Calculation o f the veiling luminance transmitted by each filter revealed that the d ifference in veiling luminance in the two filter conditions was insuff icient to result in a measurable difference in disability glare.