The Effect of Light Intensity and the Timing of Light Exposure on Choroidal Thickness

Azam Darvishi; Scott A Read; Stephen J Vincent; David Alonso-Caneiro

doi:10.1007/s44402-026-00063-x

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The Effect of Light Intensity and the Timing of Light Exposure on Choroidal Thickness

Journal article

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The Effect of Light Intensity and the Timing of Light Exposure on Choroidal Thickness

Azam Darvishi, Scott A Read, Stephen J Vincent and David Alonso-Caneiro

Ophthalmic and Physiological Optics, Vol.46, pp.616-625

2026

DOI: https://doi.org/10.1007/s44402-026-00063-x

PMID: 41882471

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Abstract

Darkness

Light intensity

Choroidal thickness

Myopia

Purpose To investigate the short-term effects of different light intensities on choroidal thickness and determine if these responses vary with time of day and refractive error. Methods Twenty young adults (10 myopes, 10 emmetropes; mean age 29 ± 4 years; mean left-eye spherical equivalent −2.53 ± 1.84 and −0.12 ± 0.20 D, respectively, were exposed to three lighting conditions: bright light (2000 lx), normal room light (350 lx) and darkness (<0.1 lx) for 60 min in a randomised order on 6 separate days, in the morning (09:00–11:00 h) and evening (17:00–19:00 h), with at least 24 h between visits and all sessions completed within a 1-month period. Choroidal thickness of the left eye was measured at baseline, during 60 min of light exposure and 30 min post-exposure, to assess recovery. Results Exposure to 2000 and <0.1 lx induced significant subfoveal choroidal thickening during the exposure period, peaking at 60 min (bright: +16 ± 4 μm; dark: +13 ± 6 μm; both p < 0.05), with values returning to baseline after 30 min of recovery. No significant changes occurred under 350 lx (p = 0.17). The greatest thickening was at the fovea (+16 ± 5 μm bright; +13 ± 6 μm dark) and parafovea (+13 ± 7 μm bright; +9 ± 6 μm dark), with smaller perifoveal changes. Bright light induced greater thickening in the evening than in the morning (p = 0.004), while darkness showed no time-of-day effect (p = 0.69). No significant refractive group differences were found (p = 0.90). Conclusions One hour of bright light or darkness caused transient choroidal thickening in young adults. Changes were most prominent in the foveal region, and bright light produced stronger evening responses. These findings demonstrate that short-term choroidal thickness is dynamically modulated by both light intensity and time of day.

Details

Title: The Effect of Light Intensity and the Timing of Light Exposure on Choroidal Thickness
Authors: Azam Darvishi (Corresponding Author) - Queensland University of Technology
Scott A Read - Queensland University of Technology
Stephen J Vincent - Queensland University of Technology
David Alonso-Caneiro - University of the Sunshine Coast
Publication details: Ophthalmic and Physiological Optics, Vol.46, pp.616-625
Publisher: Wiley-Blackwell Publishing Ltd.
Date published: 2026
DOI: 10.1007/s44402-026-00063-x
ISSN: 1475-1313
PMID: 41882471
Copyright note: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Data Availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.
Organisation Unit: School of Science, Technology and Engineering
Language: English
Record Identifier: 991219627802621
Output Type: Journal article

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