Reduced eye optical quality contributes to worse chromatic thresholds in aging

Marcelo Fernandes Costa; Livia Soledade Rego; Leonardo Dutra Henriques; Carlo Martins Gaddi; Givago Silva Souza

doi:10.3389/fnint.2023.1129315

Reduced eye optical quality contributes to worse chromatic thresholds in aging

Front Integr Neurosci. 2023 Mar 24:17:1129315. doi: 10.3389/fnint.2023.1129315. eCollection 2023.

Authors

Marcelo Fernandes Costa^{1

2}, Livia Soledade Rego¹, Leonardo Dutra Henriques¹, Carlo Martins Gaddi^{1

2}, Givago Silva Souza³

Affiliations

¹ Department of Experimental Psychology, Institute of Psychology, University of São Paulo, São Paulo, São Paulo, Brazil.
² Núcleo de Neurociências Aplicada, University of São Paulo, São Paulo, São Paulo, Brazil.
³ Tropical Medicine Center, Federal University of Pará, Belém, Pará, Brazil.

Abstract

Purpose: Aging causes substantial changes in the intraocular lens, which leads to a reduction in chromatic perception. We aimed to measure the ocular light dispersion component in relation to the reduction in color vision by aging.

Methods: Intraocular straylight was quantified psychophysically by C-Quant for light dispersion [Log(s)], reliability of the results (ESD), and psychometric sampling quality (Q). The Cambridge Color Test Trivector protocol measured the chromaticity thresholds for protan, deutan, and tritan color confusion axis in CIE 1976 u' v' units. We tested 224 subjects aged 24-68 years (106 men) with normal best-corrected visual acuity and without clinical evidence of cataracts.

Results: A significant positive correlation was found between ocular dispersion of light and chromaticity thresholds for protan (r = 0.42; p < 0.001), deutan (r = 0.49; p < 0.001) and tritan (r = 0.51; p < 0.0001) color confusion axes with a moderate effect size (η² = 0.39). However, a weak contribution of the logarithm of the straylight in predicting the chromaticity threshold for protan (b = 0.15; p = 0.025), deutan (b = 0.27; p = 0.001) and tritan (b = 0.21; p = 0.001) color confusion axes was verified in the regression coefficients. The other two measurement quality parameters estimated in the C-Quant were not correlated with chromaticity thresholds, suggesting that there are no problems with the quality of the measurement performed.

Conclusion: An increase in ocular light dispersion that occurs physiologically with aging negatively impacts the chromaticity threshold in a similar manner across all three color confusion axes. The weak regression effects suggest that neural rather than optical processes were more related to the reduction in chromaticity in aging.

Keywords: aging; chromaticity threshold; ocular optical quality; ocular straylight; psychophysical.

Grants and funding

This work was supported by the FAPESP Projeto Temático under Grant 2014/26818-2 and National Council for Scientific and Technological Development—CNPq under Grant 404603/2013-0. MC and GS are CNPq research fellows.