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A Virtual Reality Simulated Alternate Cover Test to Evaluate Adults with Strabismus
Yeabsira Mesfin1, Patrick Takla1, Maanasa Indaram1
1Department of Ophthalmology, University of California, San Francisco School of Medicine, San Francisco, California.
Objective:
Obtaining precise strabismus measurements is key in the diagnosis and management of strabismus in adults. Virtual reality (VR) has the potential to address the limitations of the standard alternate cover test (ACT) in measuring strabismus. The goal of this study was to evaluate the performance of a VR-simulated ACT in adults with strabismus.
Design:
Prospective cohort study.
Participants:
Eligible consecutive participants ≥18 years with manifest strabismus ≥5 prism diopters (PD) at either distance or near were prospectively enrolled.
Intervention:
Each patient underwent a VR-simulated ACT with eye-tracking technology (Olleyes VisuALL) followed by an ACT by a masked pediatric ophthalmologist. Bland-Altman plots, intraclass correlation coefficient (ICC), and Spearman correlation were used to compare the limits of agreement (LOA) and association between the 2 examinations for the entire cohort as well as those with deviations ≥10 PD.
Main Outcome Measures:
Level of agreement between VR and standard strabismus measurements obtained from the VR and ACT.
Results:
Of the 61 participants enrolled, 56 completed the VR test at near and 50 at distance. At distance, VR measurements were 0.88 PD higher than the ACT (upper LOA: 19.3, lower LOA: -17.6). At near, VR measurements were 0.28 PD higher than the ACT (upper LOA: 26.1, lower LOA: -25.5). For patients with manifest strabismus ≥10 PD, VR measurements were 0.26 PD lower than the ACT at distance (upper LOA: 19.5, lower LOA: -20.1) and at 3.97 PD lower at near (upper LOA: 18.8, lower LOA: -2). Wider variability was observed in patients with larger deviations. Significant correlations between VR and ACT measurements were observed at distance greater than near (ICC = 0.78, P < 0.0001; ICC = 0.57, P < 0.001, respectively). Patients with deviations ≥10 PD exhibited similar agreement (ICC: 0.72, P < 0.0001; near: ICC = 0.64, P < 0.0001).
Conclusions:
A VR-simulated ACT demonstrated good correlation to standard strabismus measurements at distance and moderate correlation at near. The VR device underestimated deviations with larger deviations and tended to overestimate in those with smaller deviations. Virtual reality with eye-tracking technology holds promise in the assessment of adults with strabismus.
Financial Disclosures:
Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
