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Dragos Rezeanu, Rachel Barborek, Maureen Neitz, Jay Neitz; A physiologically based simulation of anomalous trichromacy. Invest. Ophthalmol. Vis. Sci. 2022;63(7):2240 – F0448.
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© ARVO (1962-2015); The Authors (2016-present)
Red–green color vision deficiency (CVD) is the most common single locus genetic disorder in humans; however, only 25% of CVD individuals are dichromats who rely on two cone types for color vision. 75% are anomalous trichromats whose CVD is milder, being based on three cone types, but who are nevertheless referred to as “colorblind.” Here, we present an algorithm that computes the relative loss of color discrimination in red-green CVD individuals with varying degrees of deficiency and simulates these conditions by transforming the colors in a digital image.
Our algorithm uses the association between discrimination data from the Nagel anomaloscope and measured spectral separations from anomalous trichromats to simulate color discrimination in anomalous trichromats more generally. Using the measured primaries of an anomaloscope and cone fundamentals derived from a physiologically based photopigment template, we can predict the Rayleigh match and matching range for any pair of middle-to-long wavelength cone photopigments. This information is used to simulate the relative loss in color discrimination of an anomalous trichromat by comparing the predicted matching range against the average color normal range and applying that % loss to a digital image through LMS Daltonization.
The resulting model generates accurate simulations of CVD at any severity, as defined by the spectral separation between the two middle-to-long wavelength cones, with Rayleigh match and matching range values that agree with results from anomalous trichromats who have had their cone photopigments characterized by molecular genetics. We used the model to transform a wide range of test images, all of which illustrate the significant gap in color discrimination between dichromats and even the most severe anomalous trichromats. Even a spectral separation of 2.5 nm, with a corresponding 87.9% loss in color discrimination, leaves sufficient color information to pass the Farnsworth D-15 and identify the primary colors in most real-world scenes.
An accurate simulation of CVD at every level of severity could play an important role in establishing more inclusive employment standards for color critical work by educating the public on the difference between color “deficient” and color “blind.” As our model illustrates, most CVD individuals are very capable of discerning the colors in their environment.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
(a) Normal (b) Deuteranomalous (c) Deuteranope
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