Comparison of objective and subjective techniques of ocular deviation measurement

Document Type : Original article

Authors

Department of Optometry and Vision Sciences, School of Rehabilitation Sciences, Zahedan University of Medical Sciences

10.22038/rcm.2025.86043.1527

Abstract

Background: Measuring eye deviations is one of the most important steps in evaluating binocular vision. Small amounts of eye deviation can cause headaches and asthenopia if not managed appropriately. The aim of this study was to compare the objective and subjective deviation measurement methods.
Method: This cross-sectional study was carried out on 110 students aged 18-30 years, from Zahedan University of Medical Sciences. Assessments included refraction, near-point convergence, near-point accommodation, fusional vergences and best-corrected visual acuity. Objective measurements of near and far deviation were done using the Alternate Prism Cover Test, while subjective measurements were performed using the Maddox Rod for far and the Maddox Wing for the near. The intra-class correlation coefficient was used to check the agreement between the objective and subjective deviation angle measurement methods.
Results: The 95% limits of agreement (LoA) between the subjective and objective methods were –3.07 to 2.25 PD at far and –7.17 to 5.50 PD at near, showing that the two techniques cannot be used interchangeably. While the intra-class correlation coefficients demonstrated good statistical agreement for far (ICC=0.849) and near (ICC=0.836) deviations (P<0.001), these correlations do not offset the poor clinical agreement indicated by the LoA.
Conclusion: According to the results of this study, the range of the 95% LoA revealed a large magnitude of deviation (>5 PD), indicating a poor clinical correlation between the angle of deviation measured by the objective and subjective methods for both distances.

Keywords

Reviews in Clinical Medicine
Volume 12, Issue 4 - Serial Number 4
December 2025
Pages 131-135

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