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John R. Buch, Derek Nankivil, Jie Xu, Alex Gonzalez, Victoria Graham, Cornelis Rowaan, Juan Silgado, Guillermo Amescua, Byron L Lam, Barry Hurwitz, Jean-Marie A Parel; A pilot study on the role of spectral filtering on visual light discomfort. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2806.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study is to characterize visual light discomfort threshold (VLDT) reliability measured with the ocular photosensitivity analyzer (OPA) and to measure the effect size of differences in VLDT of ultraviolet (UV) and neutral density (ND) control lenses compared with a 476 nm high pass filter (HPF) lens. The OPA generates light stimuli (white LEDs) of varying intensities utilizing unequal ascending and descending steps along with subjective feedback to yield the VLDT.
This was a 6-visit, single-center, non-dispensing, randomized, single-masked, repeated measures 3×3 crossover study. To determine the optimum rest interval, VLDT was measured across six consecutive trials using 5, 10, and 15 minute intertest periods. Then, using the optimum rest interval, VLDT was measured with the UV filter lens, with the HPF lens, and with the ND filter lens. Skin color, iris color and macular pigment optical density (MPOD) were measured using colorimetry, iris color scale, and heterochromatic flicker photometry, respectively. Of the 11 subjects from the per-protocol population, 3 (27.3%) were female and 8 (72.7%) were male. The average age (±SD) was 24.2 (±3.3) years. VLDT was analyzed using generalized linear mixed models with the lognormal distribution. Type I error was controlled for multiple comparisons.
The intra-class correlation (ICC) was 0.88, 0.92 and 0.87 for the 5, 10, and 15 minute resting intervals, respectively. Within subject variance estimate was 0.26, 0.16, and 0.27 log(lux) for the 5, 10, and 15 minute resting intervals, respectively. The residual variance was not statistically different among resting periods based on the overall homogeneity of variance test (p=0.140). However, the ICC was slightly higher and the residual variance was lower for the 10 minute interval, so the 10 minute interval was used in subsequent experiments. Skin color and MPOD were not statistically significant covariates. VLDT did not vary between the two control lenses. Median VLDT ratio was significantly different than unity for the HPF relative to the both controls. Relative to control, the HPF reduced transmitted source energy by approximately 28% while the VLDT increased by more than 70%.
It is suggested that high energy visible (HEV) light contributes disproportionately to visual light discomfort. Alternatively, an HEV filter is highly efficacious at reducing visual light discomfort.
This is a 2021 ARVO Annual Meeting abstract.
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