Accuracy and Precision of Fixation is Correlated with Gaze Angle

Amiebenomo, Onyeka; McIlreavy, Lee; Erichsen, Jonathan T.; Woodhouse, J Margaret

Abstract

Purpose – In infantile nystagmus, the null zone tends to favour better oculomotor control even when it is eccentric. We investigated whether gaze position affects fixation in typical participants.
Methods – Nine emmetropes fixated vanishing optotype Landolt C targets at 4m, for 7 gaze angles (±45°; 15° apart) while performing a resolution threshold task. Eye movements were recorded at 1000Hz. Eye position accuracy and precision was derived from a bivariate probability density function. The isocontour surrounding the gaze positions with the highest 68% probability density was selected for further analysis. The length of the vector from the target position to the isocontour centre measured accuracy (perfect fixation is zero), and larger contour area reflected less precision.
Results – Mean eye position accuracy had a significant positive correlation with gaze angle [r(2) = 0.973, p = 0.027) as did precision [r(2) = 0.990, p = 0.010]. Mean contour shape (min/max diam.) had a significant negative correlation (less circular) with gaze angle [r(2) = -0.998, p = 0.002].
Conclusion – Fixation performance is progressively less accurate and precise with increasing eccentric gaze. Just as in people with nystagmus where nystagmus worsens outside the null zone, fixation appears to become more unstable as gaze shifts away from primary position.

• Presentation Conference Type: Conference Abstract
• Conference Name: 21st European Conference on Eye Movements
• Start Date: Aug 21, 2022
• End Date: Aug 25, 2022
• Acceptance Date: Jun 15, 2022
• Online Publication Date: Aug 21, 2022
• Publication Date: Aug 21, 2022
• Deposit Date: Aug 12, 2024
• Journal: Journal of Eye Movement Research
• Peer Reviewed: Peer Reviewed
• Volume: 15
• Issue: 5
• Pages: 87
• Public URL: https://uwe-repository.worktribe.com/output/12781237
• Publisher URL: https://bop.unibe.ch/JEMR/article/view/8878