Abstract
BackgroundThe purpose of this study was to evaluate the efficacy of a quantitative analysis method for comitant exotropia using video-oculography (VOG) with alternate cover.MethodsThirty-four subjects with comitant exotropia were included. Two independent ophthalmologists measured the angle of ocular deviation using the alternate prism cover test (APCT). The video files and data of changes in ocular deviation during the alternate cover test were obtained using VOG. To verify the accuracy of VOG, the value obtained using VOG and the angle of a rotating model eye were compared, and a new linear equation was subsequently derived using these data. The calculated values obtained using VOG were compared with those obtained using the APCT.ResultsRotation of the model eye and the values obtained using VOG demonstrated excellent positive correlation (R = 1.000; p < 0.001). A simple linear regression model was obtained: rotation of the model eye = 0.978 × value obtained using VOG for a model eye – 0.549. The 95% limit of agreement for inter-observer variability was ±4.63 prism diopters (PD) for APCT and that for test-retest variability was ±3.56 PD for the VOG test. The results of APCT and calculated VOG test demonstrated a strong positive correlation. Bland-Altman plots revealed no overall tendency for the calculated values obtained from VOG to differ from those obtained using APCT.ConclusionsVOG with alternate cover is a non-invasive and accurate tool for quantitatively measuring and recording ocular deviation. In particular, it is independent of the proficiency of the examiner and, can therefore, be useful in the absence of skilled personnel.Trial registrationClinicalTrial.gov, NCT03119311, Date of registration: 04/17/2017, Date of enrolment of the first participant to the trial: 04/25/2017.
Highlights
The purpose of this study was to evaluate the efficacy of a quantitative analysis method for comitant exotropia using video-oculography (VOG) with alternate cover
In alternate prism cover test (APCT), the subject gazes at the target with both eyes, a prism is placed in front of the uncovered eye, and an alternate cover test is performed
In the reliability analysis of eight repeated VOG tests for a model eye, the intra-class correlation coefficient was 1.000 (95% confidence interval [CI] 1.000 to 1.000; p < 0.001)
Summary
The purpose of this study was to evaluate the efficacy of a quantitative analysis method for comitant exotropia using video-oculography (VOG) with alternate cover. Methods available for measuring the angle of ocular deviation include the alternate prism cover test (APCT), Hirschberg test, and Krimsky test. Park et al BMC Ophthalmology (2018) 18:80 test measures the angle of ocular deviation using a prism and the corneal light reflex. For this reason, APCT measures the entire deviation, including tropic and phoric components, whereas the Krimsky tests only measure the tropic component. When the goal of surgery is to achieve orthotropia, APCT should be used whenever possible [1] Such tests may have limitations in recording eye movements themselves
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