The effects of yellow filter on daily visual function.

Abstract

Although blue-blocker lenses are commonly prescribed to low vision patients, there is no consensus on whether they provide reliable improvements in patients’ daily visual function. Here we evaluate the effects of a yellow filter (515nm long-pass glass filter) in normally-sighted young adults. Twelve observers performed a battery of visual tasks using their left eye with and without the filter. As expected, color discrimination (Farnsworth-Munsell 100-hue color vision test) was much worse in the with-filter condition (average total error score: 38 vs. 235), p<0.001. The with and without-filter conditions did not differ on the measurements of visual acuities (Bailey-Lovie for distance; ETDRS 2000 for near), contrast sensitivities (Mars and qCSF tests), and reading speeds (MNREAD at fovea; qReading-RSVP test at 10° in the lower field (n=9)). We also measured pupil sizes for nine of the observers when they were viewing an array of full-screen solid colors on a LCD (42cd/m2 for colored stimuli and 270cd/m2 for white), twelve illuminated Munsell color sheets, and twelve computer-displayed natural scene images with pre-selected fixation locations to control for eye movements. Pupil size was on average larger for the with-filter condition in all three viewing tasks. The same results held when we equated luminance between with and without-filter conditions for the solid colors on LCD. Our results demonstrated that a yellow filter can have significant impacts on color vision and pupil size but not on visual acuity, contrast sensitivity, and reading speed. The enlargement of pupil size in the with-filter condition may explain previous subjective reports of brightness enhancement with blue-blocker lenses.