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J W L. Lewis, Lei Shi, E E. Hartmann, Naser T. Naser, Ying-Ling Chen, Ming Wang; Pilot Study of an Automatic Assessment of Ocular Alignment. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2513.
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© ARVO (1962-2015); The Authors (2016-present)
To design an objective, binocular, and friendly/relaxed testing method to diagnose strabismus and ocular alignment disorders.
Our stimulus was a bulls-eye target moving in a horizontal trajectory (10 sec duration) displayed on a computer screen. Subjects tracked the display using a binocular viewer with a nasal divider that produced binocular viewing at the center region of the screen and 2 monocular viewing zones at either side of the screen. While the examinee followed the target’s trajectory through the 3 viewing zones, test results of monocular and binocular smooth pursuit were automatically obtained. The absolute eye position was instantaneously captured and used in the analysis so that head movement did not affect performance. We used dynamic Hirschberg analysis to monitor the binocular orientation, gazing angle, and convergence. The initial study used 40 optometry students. Dynamic testing allowed us to obtain the Hirschberg ratio (HR) and fovea kappa angle (K) for each individual eye.
The mean HR in 78 normal eyes was 24.9 deg/mm (SD 3.1). Mean K was 5.48 degrees (SD=2.69 degrees). HR and K are self-corrected to obtain the gazing analysis. Variation of saccade pursuit behavior was also observed among the normal objects. One subject with strabismus showed an unambiguous positive result in comparison to the normal subjects.
The design shows promising automatic features for pediatric vision screening. It can be easily combined with the dynamic photoscreening device. The primary suggestion was to increase the speed of the target. An interactive video game could be integrated to better ensure gazing attention to the target. This rapid diagnostic method may be even more sensitive when the parameters of the 2 eyes of the same individual are compared.
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