Interaction between indoor and outdoor lighting conditions and accommodation stimuli on ocular biometry

Purpose : To investigate the impact of different lighting conditions, accommodative stimuli, and their interaction on ocular biometry. Methods : Twenty healthy young adults (6 myopes, 14 emmetropes; mean age 20.6 (range, 19-22) years) participated in the study. After a 10 min washout period of viewing a target >4 m away, participants were exposed to 30 min indoor ambient lighting (≤1000 lux) without any accommodative stimulus (0 D). Following this, they were exposed sequentially to 10 min of 3 D and 5 D accommodative stimuli with a washout period of 10 min in between the two stimuli. The same protocol was repeated for outdoor ambient lighting (≥10,000 lux) on a different day. Axial length (AL) and sub-foveal choroidal thickness (SFCT) were measured using Lenstar LS900 before and immediately following each experimental condition. All data were collected between 9 am and 1 pm. A repeated measures ANOVA was used to analyse the main effects and interaction of lighting and accommodative stimuli on changes in ocular biometry. All results are reported as average ±SEM. Results : Both SFCT and AL showed main effect of accommodation (0, 3, 5 D) and lighting conditions (indoor, outdoor). A significant interaction between lighting and accommodation was found for the changes in SFCT (P<0.05) but not for AL (P=0.821). In unaccommodated eyes, SFCT showed a mean difference of 13.8±2.9 µm (P<0.001) between outdoor and indoor lighting conditions, whereas, under 3 D and 5 D of accommodation, the difference was 5.6±3.1 µm (P=0.095) and 3.4±3.1 µm (P=0.286). Equally, the mean differences in SFCT between different accommodative stimuli were higher for outdoor lighting (0–3 D: 14.9±2.4 µm, P<0.001; 0–5 D: 22.1±2.6 µm, P<0.001; 3–5 D: 7.2±2.1 µm, P=0.01) compared to indoor lighting (0–3 D: 6.8±2.1, P<0.05; 0–5 D: 11.67±3.18 µm, P<0.01; 3–5 D: 4.9±2.9, P=0.308) (Fig. 1). Change in ocular biometry was not different among myopes and emmetropes. Conclusions : Outdoor lighting for 30 min can induce choroidal thickening relative to indoor lighting in unaccommodated eyes. Outdoor lighting shows a protective effect against choroidal thinning induced by both 3 D and 5D of accommodative stimulation. This abstract was presented at the 2025 ARVO Annual Meeting, held in Salt Lake City, Utah, May 4-8, 2025.