Effect of “color-correcting glasses” on chromatic discrimination in subjects with congenital color vision deficiency

Abstract

Purpose : Congenital red-green (RG) color vision deficiency (CVD) is an X-linked condition affecting approximately one in twelve males. The aim of this study was to use the Color Assessment and Diagnosis (CAD) test to objectively examine two types of commercially available glasses that are claimed to “correct” CVD.

Methods : Twenty-seven males (aged 18 to 91 years) with genetically confirmed RG CVD were recruited: ten deuteranopic, eight deuteranomalous and nine protanopic. Subjects were tested with the CAD test under normal conditions and after adapting for 30 minutes under CIE Standard Illuminant D65 lighting conditions while wearing one of two types of color correcting glasses (EnChroma or O₂ Amp Oxy-Iso). Sixteen subjects underwent testing with both types of glasses.

Results : Without glasses, chromatic discrimination thresholds ranged from 3.87 to 46.42 for the RG axis and 0.86 to 16.75 for the yellow-blue (YB) axis (where CAD units are normalized to 1 for the standard normal observer). Discrimination improved along the RG axis both for deuteranopic (p <.001) and deuteranomalous (p =.05) subjects wearing O₂ Amp glasses. In protans, the glasses resulted in a rotation of the axis of confusion from protan to deutan, but there was no significant change in RG (p =.83) or BY (p =.11) threshold values. The EnChroma glasses had no significant effect on RG thresholds for either protans (p =.97) or deutans (p =.68) but resulted in poorer BY discrimination for deutans (p <.001).

Conclusions : Both the O₂ Amp and the EnChroma glasses differentially modulate the intensities of certain wavelengths of light reaching the eye. Color vision is, by definition, the ability to discriminate wavelength independently of intensity, thus it is not possible for either type of glasses to improve wavelength discrimination for dichromats beyond about 550 nm. However, colored filters can introduce sufficient luminance cues to isochromatic stimuli to allow individuals with CVD to “cheat” on standard color vision tests, as the O₂ Amp glasses did for deutans. Theoretically, colored filters could sharpen color discrimination for anomalous trichromats for certain spectral distributions in the RG region; however, no evidence for this was found in the case of CAD stimuli. Claims by both companies of “curing color blindness” or allowing individuals to “see new colors” simply are not supported by our data.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.