Case Report: Effect of Haploscopic Filter on Contrast Sensitivity Function and Colour Vision Tests

Abstract

Significance: The options that can help subjects with congenital color vision defect, to a better professional and leisure adaptation, are very limited. Different haploscopic lenses can be considered, and their effects need to be investigated in patients with different defect. Purpose: The purpose of this study was to present and discuss the effect of a pair of asymmetric longpass filters fitted for deuteranopia, with the result of a 60% improvement on distinguishing red-green plates when compared with baseline. Case Report: We report a case of a 51-year-old male with congenital deuteranopia fitted with haploscopic Chromagen filters. During the 2-month follow-up, we observed a decrease in left eye logMAR visual acuity and contrast sensitivity with an increased ability to discriminate the plates of different color vision tests (Ishihara, Farnsworth and Hardy-Rand-Rittler). The visual outcomes are discussed considering the spectral sensitivity curves of each filter, measured with a spectrophotometric device. Conclusions: This report describes an improvement in the ability to resolve color vision plates after using asymmetric haploscopic filters showing a left eye decrease in logMAR visual acuity and contrast sensitivity function. Subjects with a history of color vision deficiency might benefit from using haploscopic filters that selectively minimize the transmittance within a specific bandwidth in order to improve the color discrimination in deutan colour vision deficiency. The simultaneous analysis of the color vision outcomes and transmittance spectrum of the haploscopic filters might contribute to a better understanding of the mechanisms behind the claimed efficacy of these devices.