Therapeutic effects of virtual reality-based accommodation training device on accommodative excess asthenopia

Objective  To analyze the therapeutic effect of a virtual reality (VR)-based accommodation training device on accommodative excess visual fatigue.

Methods  A case-control study was conducted.A total of 20 normal subjects (20 eyes) and 20 patients with accommodative excess visual fatigue (20 eyes) were recruited at Zhongshan Ophthalmic Center, Sun Yat-sen University between January and December 2022.The study consisted of two phases.In the first phase, the effect of watching videos with VR glass on the subjects’ subjective and objective visual function was evaluated.Normal subjects wore VR device to watch a 2D video for 30 minutes, and assessments were performed before and after viewing.These assessments included binocular accommodation/convergence function (accommodation response, accommodative convergence to accommodation ratio [AC/A]), tear film function (first tear film break-up time), subjective symptoms (visual fatigue score), and basic visual health parameters including best corrected visual acuity (BCVA) and intraocular pressure (IOP).In the second phase, the improvement in subjective and objective visual fatigue metrics with the VR-based accommodation training device was investigated.Patients with visual fatigue were divided into a traditional training group using traditional flipper lenses and a VR training group using the VR accommodation training device, with 10 eyes in each group.The effects of the VR accommodation training device on indicators such as accommodative sensitivity, accommodation response, convergence function, visual fatigue score, acceptability score, system usability score, BCVA, and IOP were evaluated and compared between the two groups.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Zhongshan Ophthalmic Center, Sun Yat-sen University (No.IIT2021007).Written informed consent was obtained from each subject.

Results  In normal subjects, there was no statistically significant difference in first tear film break-up time, distance phoria, near phoria, AC/A, accommodative response, BCVA, or IOP before and after 30 minutes of continuous viewing of 2D video using VR glass ( t=1.155, 1.360, 4.479, 1.979, -1.249, -3.017, 2.211; all P>0.05).The visual fatigue score remained unchanged at (1.00±0.00) points before and after viewing.Among the subjects with visual fatigue, there were statistically significant differences in binocular accommodative sensitivity, dominant eye accommodative sensitivity, and BCVA before and after using the VR accommodation training device ( F=8.693, 4.078, 4.942; all P<0.05).Ocular accommodation sensitivity at 8 weeks after training was improved compared with 1 week after training, and BCVA at 4 weeks after training was improved compared with before training, and the differences were statistically significant (both P<0.05).In the VR training group, the average tear film break-up time, first tear film break-up time, and BCVA increased and the visual fatigue score decreased compared with before training, the differences were statistically significant (all P<0.05).In the traditional training group, the accommodation sensitivity of the dominant eye increased after training compared with before training, with a statistically significant difference ( P<0.05).

Conclusions  Watching 2D videos with VR glass for 30 minutes does not induce subjective or objective symptoms of visual fatigue.The VR-based accommodation training paradigm effectively improves accommodative sensitivity and alleviates subjective symptoms of visual fatigue in individuals with accommodative excess visual fatigue.

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