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Hess Lancaster Screen Test with Eye Tracker: An Objective Method for the Measurement of Binocular Gaze Direction
Elvira Orduna-Hospital1, Luz Maurain-Orera1, Carmen Lopez-de-la-Fuente1
1Department of Applied Physics, University of Zaragoza, 50009 Zaragoza, Spain.
Life (Basel, Switzerland)
|March 29, 2023
Summary
This study demonstrates that using an eye tracker to perform the Hess Lancaster Screen Test (HLST) provides more accurate measurements of vertical deviations than traditional methods. Eye tracking offers objective data for evaluating binocular vision, complementing standard eye exams.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- The Hess Lancaster Screen Test (HLST) is a standard clinical tool for assessing binocular vision.
- Traditional HLST performance relies on subjective interpretation by an examiner.
- Objective measurement of eye movement conjugacy and gaze direction during HLST is needed.
Purpose of the Study:
- To objectively measure eye movement conjugacy and gaze direction during the Hess Lancaster Screen Test (HLST) using an eye tracker.
- To compare eye-tracker-based HLST results with traditional subjective HLST performance in healthy subjects.
Main Methods:
- Eye movement conjugacy and gaze direction were measured using an eye tracker (Tobii Pro Fusion) during HLST in control subjects.
- Subjects without binocular dysfunction, suppression, or visual acuity less than 20/25 were included.
- A custom program (Etracker Parse Video) analyzed prismatic deviation between eyes.
Main Results:
- Horizontal prismatic deviations showed similar directions across eye-tracking, manual HLST, and Maddox rod methods.
- Vertical deviations, especially small ones, were quantified more accurately with the eye tracker.
- Magnitude of deviation varied between methods, but direction remained consistent.
Conclusions:
- The Hess Lancaster Screen Test (HLST) is valuable for recording heterophoria/heterotropia but is not diagnostic alone.
- Eye-tracker-based HLST provides objective and more accurate measurements, particularly for vertical deviations.
- Objective eye-tracking evaluation of HLST complements traditional binocular vision examinations.
