Impact of ChromaGen lenses on colour vision test performance of individuals with congenital colour vision deficiency

Background: Congenital colour vision deficiency (CVD) is a common genetic anomaly that affects an individual’s ability to distinguish specific colours. ChromaGen filters are designed to enhance colour discrimination in individuals with red-green CVD. However, data supporting their effectiveness is limited. This study aimed to evaluate the effect of ChromaGen filters on colour discrimination using various colour vision tests. Methods: Eighty male individuals with CVD participated in this study; there were 14 deuteranopes, 43 deuteranomalies, 5 protanopes and 18 protanomalies. All participants completed the anomaloscope, Ishihara 38-plate, Hardy Rand Rittler (HRR) 4^th edition, Waggoner pseudoisochromatic 24 (W-PIP24) and the Waggoner computerised (W-Comp) tests. Three types of ChromaGen lenses were used: magenta (lens M), pink (lens P) and violet (lens V). Results: The results for the Ishihara 38-plate, HRR 4^th edition and W-PIP24 tests showed that all three ChromaGen lenses decreased the average number of errors significantly compared with baseline (p < 0.0001). Lens P improved the Ishihara and HRR findings the most, while lens M was more effective on the Waggoner PIP24 test. However, dichromats, particularly protanopes, showed minimal benefit, with none passing any test using the lenses. Conclusions: ChromaGen filters may influence the nature of CVD without reducing its severity. The dichromatic individuals showed minimal improvement, with none of the participants with protanopia passing any of the tests using any ChromaGen lens.