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

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).

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).

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.

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.