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Monocular Versus Binocular Calibrations in Evaluating Fixation Disparity With a Video-Based Eye-Tracker
Aiga Švede1, Elīna Treija2, Wolfgang Jaschinski3
1Department of Optometry and Vision Science, University of Latvia, Riga, Latvia aiga.svede@lu.lv.
Perception
|November 13, 2015
Summary
Monocular calibration provides a more physiologically accurate measurement of fixation disparity compared to binocular calibration. This method is better for understanding the full scope of vergence errors in the visual system.
Area of Science:
- Oculomotor function
- Vision science
- Neuroscience
Background:
- Fixation disparity, an oculomotor vergence error, requires precise calibration for accurate measurement.
- Monocular calibration assumes foveal fixation, while binocular calibration may be influenced by existing vergence errors.
Purpose of the Study:
- To compare the precision and physiological appropriateness of monocular versus binocular calibration methods for measuring fixation disparity.
- To evaluate the impact of calibration type on fixation disparity measurements during a dot scanning task.
Main Methods:
- Participants underwent both monocular and binocular calibration procedures.
- Fixation disparity was measured during a dot scanning task following each calibration type.
- Statistical analysis compared fixation disparity values obtained from the two calibration methods.
Main Results:
- A significant difference in fixation disparity was observed between monocular and binocular calibrations in 11 out of 19 participants.
- Heterophoria had a greater impact on fixation disparity measurements following monocular calibration compared to binocular calibration.
Conclusions:
- Monocular calibration appears to yield a more physiologically plausible fixation disparity measurement.
- Monocular calibration is suggested as a more appropriate method for comprehensively studying fixation disparity and associated vergence states.
