A Novel Virtual Reality-Based System for Measuring Deviation Angle in Strabismus: A Prospective Study

<b>Background/Objectives</b>: To develop a new Virtual Reality (VR) system software for measuring ocular deviation in strabismus patients. <b>Methods</b>: This prospective study included subjects with basic-type exotropia (XT) and non-refractive accommodative esotropia (ET). Ocular deviation was measured using the alternate prism cover test (APCT) and two VR-based methods: target offset (TO) and a newly developed camera rotation (CR) method. <b>Results</b>: A total of 28 subjects were recruited (5 cases were excluded for preliminary testing and 5 for not meeting inclusion criteria). Among the 18 included patients, 10 (66.7%) had XT and 5 (33.3%) had ET. The median age was 21.5 years (IQR 17 to 25). The mean age was 22.3 years (range: 9-46), with 5 (27.8%) having manifest strabismus and 12 (61.1%) measured while wearing glasses. VR-based methods (TO and CR) showed comparable results to APCT for deviation angle measurements (<i>p</i> = 0.604). Subgroup analysis showed no significant differences in ET patients (all <i>p</i> > 0.05). In XT patients, both TO and CR underestimated deviation angles compared to APCT (<i>p</i> = 0.008 and <i>p</i> = 0.001, respectively), but no significant difference was observed between the two methods (<i>p</i> = 0.811). Linear regression showed CR had a stronger correlation with APCT than TO (R² = 0.934 vs. 0.874). <b>Conclusions</b>: This newly developed VR system software, incorporating the CR method, provides a reliable approach for measuring ocular deviation. By shifting the entire visual scene rather than just the target, it lays a strong foundation for immersive diagnostic and therapeutic VR applications.