Abstract
Purpose: To investigate the usefulness and efficacy of a novel eye-tracking device that can objectively measure nine gaze-directions.Methods: We measured each of the nine gaze-directions subjectively, using a conventional Hess screen test, and objectively, using the nine gaze-direction measuring device, and de-termined the correlation, addition error, and proportional error. We obtained two consecu-tive measurements of the nine gaze-directions using the newly developed device in healthy young people with exophoria and investigated the reproducibility of the measurements. We further measured the nine gaze-directions using a Hess screen test and the newly developed device in three subjects with cover test-based strabismus and compared the results. Results: We observed that the objective measurements obtained with the newly developed gaze-direction measuring device had significant correlation and addition error compared to the conventional subjective method, and we found no proportional error. These measure-ments had good reproducibility.Conclusion: The novel device can be used to observe delayed eye movement associated with limited eye movement in the affected eye, as well as the associated excessive movement of the healthy eye in patients with strabismus, similar to the Hess screen test. This is a useful device that can provide objective measurements of nine gaze-directions.
Highlights
We observed that the objective measurements obtained with the newly developed gaze-direction measuring device had significant correlation and addition error compared to the conventional subjective method, and we found no proportional error
The Hess screen test is an extremely useful test for quantifying limited eye movement by measuring ocular deviations in each of the nine gaze-directions and for identifying paretic muscles; it is frequently implemented in clinical ophthalmology (Roper-Hall, 2006)
In this study we have newly developed a device that can objectively measure the nine gaze-directions using gaze-detection technology and compare the findings obtained with this device to those from the Hess test, in patients with strabismus
Summary
The Hess screen test is an extremely useful test for quantifying limited eye movement by measuring ocular deviations in each of the nine gaze-directions and for identifying paretic muscles; it is frequently implemented in clinical ophthalmology (Roper-Hall, 2006). The most important feature of the Hess screen test is that it can visually capture the patient’s eye movement in the nine gaze-direc-. The Hess screen test cannot be used for measuring patients with suppression because the grid is displayed in one eye and the target is displayed in the other eye under the red–green dichoptic separation (Pratt-Johnson & Tillson, 1984). The Hess screen test is mainly used in patients with strabismus, these patients often develop the suppression phenomenon, rendering the test unsuitable (Pratt-Johnson, 1992). Since this is a subjective test, patient response is essential
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