Reliability and Validity of a 9-Point Ocular Alignment Test of Cardinal Gaze using Eye Tracking

Abstract

The purpose of this study is to determine the reliability of eye-tracking enabled 9-Point Motor Function Test and to determine the validity of the eye-tracking system compared with a traditional Cover Test (CT). Fifty participants between the ages of 19-61 years were tested by a veteran Board-Certified Optometrist using the RightEye 9-Point Motor Function Test (MFT; eye tracking test) and a Cover Test. Participants completed both the 9-Point MFT and the Cover Test in random order and completed the 9-Point MFT test twice to assess test-retest reliability. Reliability was evaluated using Cronbach’s Alpha (CA). Overall reliability was acceptable to excellent per statistical standards. CA were above an acceptable level of .7. Interpupillary distance and pupil diameter were >.9 which is considered excellent. CT and eye tracker displacement were found to be significantly related via Chi Square analysis (P< .001). Logistic regression showed accuracy for left eye as 79.1% and right eye 86.3%. ROC curves were significant (P< .001) for left and right eye displacement. AUC was very high at .879 and .903 respectively. The 9-Point MFT and resulting metrics were deemed to pass reliability and validity statistical standards and as such may provide clinicians with consistent quantifiable information on positions of gaze.