Work

The effects of a HEV ‐filtering contact lens on the brightness of natural images

Year: 2025

Type: article

Abstract: PURPOSE: Yellow filters, including high-energy-visible (HEV) filtering lenses, have been thought to increase the subjective brightness of real-world scenes, but laboratory results are mixed. This study used a brightness matching technique modified to present natural images using a broad spectrum of wavelengths: a visibly clear control contact lens was compared to a contact lens containing a HEV-filtering additive. METHODS: A total of 121 subjects were tested (mean age = 33.8 ± 13.6 years). A stratified, controlled, prospective, randomised, double-masked, bilateral, non-dispensing, crossover design was used. Participants attended two study visits separated by a washout period and were randomly assigned to wear a HEV-filtering contact lens or a clear control lens binocularly, counterbalanced on the second visit. Spherical (n = 41), multifocal (n = 40) and toric (n = 40) soft contact lenses were tested. Ten natural scenes were presented using a slide projector with a 550-watt xenon light source. An adjustable comparison (broadband but short-wave deficient), produced using parallel optics with a 1000-watt xenon source, was varied based on the subject's judgement to match the brightness of the adjacent natural image. Three ascending/descending trials for each image were used to obtain the match. RESULTS: The amount of energy needed to match the natural images was consistently (i.e., across all images and subject groups) higher with the contact lenses that contained the HEV-filter. Additionally, estimated log relative energy differences between HEV- and non-HEV-filter lenses were 0.13, 0.14 and 0.17 for spherical, multifocal and toric lenses, respectively. CONCLUSION: The collection of images appeared ≈12% brighter (averaged across spherical, multifocal and toric lenses on a log scale) when wearing the HEV-filtering lenses; this translates to about 40% more energy needed to match the comparison field with the adjacent images. These results illustrate that lenses filtering HEV light are capable of increasing the subjective brightness of a naturalistic scene.

Source: Ophthalmic and Physiological Optics

DOI: 10.1111/opo.70035