Assessing chromatic discrimination in individuals varying in iris color and ethnic origin

Paramei, Galina V. and Nwanedo, Nnaemeka and Owen, Robin and Zlatkova, Margarita and Senna, Irene (2024) Assessing chromatic discrimination in individuals varying in iris color and ethnic origin. Journal of the Optical Society of America A, 42 (5). B56-B67. ISSN 1084-7529

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Abstract

This study aimed to investigate how variation in iris color, along with ethnic origin, affects color vision. For color vision deficiency screening, the Ishihara, D-15, and D-15d tests were employed. Chromatic discrimination was assessed in normal trichromats using the Cambridge Colour Test (CCT). Three groups were tested: light-eyed White (N = 30), hazel-eyed White (N = 30), and brown-eyed Black (N = 29). Black observers revealed significantly higher CCT measures—protan and tritan thresholds (Trivector) and Ellipse measures (major axis, axis ratio, and angle); no significant differences were found between the two White observer groups. We attribute Black observers’ subtle tritan-type impairment to prereceptoral factors, in particular, the higher optical density of the macular pigment, which filters out short-wavelength light, affecting S-cone-mediated chromatic discrimination, and, also, is likely to reduce retinal illuminance. The elevated protan thresholds are discussed in relation to the receptoral level; considered are possible causes of genetically determined L-cone characteristics in observers of African descent.

Item Type:	Article
Additional Information and Comments:	This version is the author accepted manuscript. The final, published version is available from: https://doi.org/10.1364/JOSAA.543952
Faculty / Department:	Faculty of Human and Digital Sciences > School of Health and Sport Sciences Faculty of Human and Digital Sciences > School of Psychology
Depositing User:	Irene Senna
Date Deposited:	20 Jan 2025 14:24
Last Modified:	20 Jan 2025 14:25
URI:	https://hira.hope.ac.uk/id/eprint/4560

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