Changes of Choroidal Thickness Varied Due to Different Lunch Break Posture and Refractive

Abstract Background The choroid is crucial in myopia prevention and control research. This study aimed to investigate the effects of different lunch break postures and refractive errors on choroidal thickness (CT) and choroidal vascular volume (CVV). Methods Healthy adult participants underwent a 45-minute lunch break in three different postures on consecutive days: lying lunch break, sitting head-on-arms lunch break, and sitting no lunch break. SS-OCTA measured CT and CVV in the macula before and after each lunch break. Changes in CT were also evaluated across different refractive errors. Results Among 40 adults (80 eyes), the average CT change was 11.62µm for lying lunch break, significantly higher than sitting head-on-arms lunch break (2.60µm) and sitting no lunch break (1.39µm) (both p < 0.0001). Average CVV changes were 8.5µm³ for lying lunch break, 1.9µm³ for sitting head-on-arms lunch break, and 1.3µm³ for sitting no lunch break. CT changes strongly correlated with CVV changes (F1,2158 = 306.1, p < 0.0001). During sitting head-on-arms lunch break, CT decreased by 6.00 ± 14.17 µm in the emmetropia and low hyperopia group, significantly different from other groups (all p < 0.0001). Conclusions Lying down during lunch breaks is most conducive to choroidal thickening, driven by increased CVV. Sitting head-on-arms may lead to choroidal thinning in people with emmetropia or low hyperopia. When considering the development of myopia in children and adolescents, it is suggested that LLB may serve as a protective factor while sitting head-on-arms lunch break may act as a risk factor.