Development and Clinical Validation of a Digital Eye-Tracking–Based Cover Test for Ocular Misalignment

Purpose: To develop and clinically validate the DIVE Cover Test (DCT), a portable eye-trackingbased digital implementation of the cover test, and to assess its diagnostic accuracy, agreement with the clinical reference standard (Classic Cover Test [CCT]), and repeatability across coveruncover (CUT) and alternate cover test (ACT) phases and across horizontal and vertical axes.Design: Prospective clinical validation study.Participants: Sixty-eight participants aged 3 to 74 years, including healthy controls and patients referred for strabismus evaluation.Methods: Participants underwent two repetitions of the DCT and two independent CCT examinations performed by experienced clinicians at near (65 cm).The order of the four assessment blocks was randomized.Diagnostic performance (sensitivity/specificity) for detecting ocular misalignment was calculated using CCT classification as reference.Agreement and repeatability were evaluated using Bland-Altman mean differences and 95% limits of agreement (LoA), intraclass correlation coefficients (ICC[2,k]), and Pearson correlations, separately for CUT versus ACT and horizontal versus vertical components.Main Outcome Measures: Sensitivity and specificity for detection of ocular misalignment; intermethod agreement between DCT and CCT; test-retest repeatability of the DCT; and interobserver agreement of the CCT.Results: For detecting any deviations, the DCT achieved 85% sensitivity and 98% specificity in CUT, and 92% sensitivity and 87% specificity in ACT.Agreement between DCT and CCT was strongest for horizontal deviations, particularly during ACT (mean difference -1.3 prism diopters[PD]; LoA -8.0 and 5.4 PD).Inter-method ICCs were high for horizontal deviations (CUT 0.93; ACT 0.96) and moderate-to-high for vertical deviations (both phases 0.81).DCT test-retest repeatability was excellent (ICC ≥0.93 across axes and phases), with narrow LoA (±3.8 to ±4.6 PD).CCT interobserver agreement was also high (ICC ≥0.95 across phases and axes). Conclusions:The DCT demonstrates high diagnostic accuracy, strong agreement with the clinical reference standard, and excellent repeatability.Phase-specific (CUT vs ACT) and axis-specific (horizontal vs vertical) analyses support the DCT as a practical, portable, and objective tool for quantifying ocular misalignment in clinical settings.