Abstract / Summary
Background: Axial ocular length is an objective measure of the growth of the eye, and is also a commonly used measure in research into myopia control because it is less dependent than refraction on the accommodative state. Learner visual conditions in virtual-reality (VR) and augmented-reality (AR) head-mounted display (HMD) devices may change one or more of the following: accommodation, vergence, visual fatigue and near-work behavior, but there is limited evidence for long-term, permanent axial elongation. Objective: To demonstrate a longitudinal study of the relationship between V/R exposure and changes in axial ocular length in 100 adolescents that had assumed residency in Mosul, Iraq, and who were studied with optical biometry (IOLMaster 700). Methods: A prospective cohort study was defined, lasting for 24 months. 50 adolescents were categorized as higher exposure (7+ hours/week) and 50 were categorized as lower exposure as comparison (less than 1 hour/week). The following parameters were evaluated: Axial length, Spherical equivalent refraction after cycloplegic, Outdoor time, Conventional near work, Myopia history and Visual symptoms. Main illustrative analysis was a comparison of groups by 24-month changes in axial length, with multivariable linear regression for analysis, with prespecified covariates. The reporting of study was designed following the principles of the cohort study and the STROBE guidelines. Results: The change in mean AL over 24 months was 0.389 mm in the higher-exposure group and 0.216 mm in the lower-exposure group for an unadjusted difference of 0.173 mm (95% confidence interval [CI], 0.126–0.220; p<0.001). This difference in estimated higher-exposure versus lower-exposure was 0.118 mm (95% CI, 0.066-0.170; p<0.001) after adjustment. Of the participants 50.0% experienced rapid elongation (at least 0.20 mm per year), and 6.0% experienced this at the very least. Conclusions: This study showed the feasibility of using longitudinal optical –biometry study to assess the level of exposure to VR/AR and the axial length of the eye in Mosul, and showed that higher exposure may be correlated with longer axial length in Mosul.