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Rath Itthipanichpong, Robert W Massof; Effect of color filter lenses on luminance contrast and color contrast. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1831.
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© ARVO (1962-2015); The Authors (2016-present)
Color filters have long been used as a low vision aid to control glare, improve quality of vision and enhance contrast. Most reported benefits of color filters are subjective and highly variable. But in the case of contrast enhancement, if beneficial, one would expect to observe a physical increase in contrast. Our study aims to evaluate the effect of color filters on luminance contrast and color contrast using common targets that low vision patients have trouble seeing.
A spot chromameter was used to measure luminance and chromaticity of 4 different visual stimuli and their backgrounds: eyebrow/skin, lip/skin, large black text/white background and tread/riser of indoor steps. Measurements were made through and without 4 color filters commonly advised to low vision patients: yellow (NoIR#465), orange (NoIR#505), plum (NoIR#88) and NoIR polarized gray. All measures were made under indoor incandescent illumination. Color appearance differences between each stimulus and its background were estimated using CIELAB △E (the conventional criterion for a just noticeable difference is △E=2.3).
Yellow and orange filters increased color contrast(△E) compared to no filter for all stimuli. For the yellow filter, △E increased from 13.58 to 21.29, 14.80 to 22.76, 52.05 to 61.25, and 16.38 to 19.47 for lip, eyebrow, black text and indoor step, respectively. For the orange filter, △E increased from 13.58 to 16.13, 14.80 to 20.58, 52.05 to 76.09 and 16.38 to 21.87 for lip, eyebrow, black text and indoor step respectively. Compared to no filter, the plum and gray filters reduced △E for all targets, thereby making color contrast less visible. (△E reductions for plum/gray = -1.04/-7.40, -2.68/-6.53, -12.49/-22.84, -3.84/-6.36 for lip, eyebrow, black text and indoor step respectively). There is only a small effect of the color filters on luminance contrast alone compared to no filter for all stimuli (range of change in log contrast =-0.07 to 0.03).
Yellow and orange filters can increase color contrast of common visual stimuli compared to no filter. The plum and gray filter resulted in a reduction of color contrast. There was no meaningful change in luminance contrast when comparing any color filter to no filter. We conclude that the physical changes in the visibility of common stimuli when wearing color filters that attenuate short wavelength light, manifest as increases in color contrast, not luminance contrast.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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