Visual Function Under Bright Light Conditions Tested Using a Blue-Light Absorbing or Clear Lens in Pseudophakic Patients

Abstract

Purpose: To evaluate the visual performance of a blue-light filter (BLF). The following visual parameters were assessed: glare disability (GD); chromatic contrast (CC); two-point light thresholds; and dysphotopsia symptoms (snowball and spoke diameter). Methods: Twenty-five pseudophakic patients previously implanted with a “UV-only” intraocular lens (IOL) were tested using a single-masked randomized cross-over design. In the control condition, a UV-only filter (matched to the implant) was used. In the test condition, a BLF was used (matching the absorbance profile of a common BLF IOL; Acrysof Natural and Clareon; Alcon Research Ltd). The intensity (expressed as log relative energy, LRE) of broad-band xenon light and a sky-blue background needed to veil a central grating target was used to measure GD and CC, respectively. The diameter of spokes/snowballs was determined by measuring their lateral extent induced by a bright white point source. Two-point light thresholds were measured as the separation between two small relatively intense point sources of light (Rayleigh criterion). Results: The BLF test lens resulted in improved CC (LRE 2.04 vs 1.83) and GD (LRE = 2.46 vs 2.27, p < 0.001). Snowballs (49 vs 69 mm, p < 0.01) and spoke (139 vs 171, p < 0.001) diameters were also reduced in the BLF condition. Conclusion: About 6% and 10% more light energy was needed to occlude the grating stimulus for GD and CC. Light spread measured using the two-point technique was about 26% less for the BLF. The BLF reduced snowballs and spokes by about 24% and 19%. The BLF significantly improved function across a variety of visual indices.