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

To develop and clinically validate the DIVE Cover Test (DCT), a portable eye-tracking-based 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 cover-uncover test (CUT) and alternate cover test (ACT) phases and across horizontal and vertical axes.

A prospective clinical validation study.

Sixty-eight participants aged 3 to 74 years, including healthy controls and patients referred for strabismus evaluation.

Participants underwent 2 repetitions of the DCT and 2 independent CCT examinations performed by experienced clinicians at near distance (65 cm). The order of the 4 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 (ICCs[2,k]), and Pearson correlations, separately for CUT versus ACT and horizontal versus vertical components.

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.

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). Intermethod ICCs were high for horizontal deviations (CUT 0.93; ACT 0.96) and moderate-to-high for vertical deviations (both phases 0.81). The DCT test-retest repeatability was excellent (ICC ≥0.93 across axes and phases), with narrow LoA (±3.8 to ±4.6 PD). Classic cover test interobserver agreement was also high (ICC ≥0.95 across phases and axes).

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.

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