Comparison of image-based quantification methods in evaluating fixation stability using a remote eye tracker in...

Area of Science:

• Ophthalmology and Vision Science
• Human Factors and Ergonomics

Background:

• Fixation stability is crucial for visual tasks and can be assessed using various quantitative methods.
• Different image-based area calculations, including bivariate contour ellipse area (BCEA), kernel density estimation (KDE), and Scanpath, offer distinct ways to measure fixation stability.

Purpose of the Study:

• To quantitatively evaluate and compare the fixation stability of individuals with abnormal and normal phoria.
• To assess the efficacy of image-based areas derived from BCEA, KDE, and Scanpath methods in measuring fixation stability.

Main Methods:

• A prospective cross-sectional study involving 65 participants (45 abnormal phoria, 20 normal phoria).
• Eye movements were recorded using a remote eye tracker and analyzed using RStudio software.
• Image-based areas for fixation stability were calculated using ImageJ software.

Main Results:

• Fixation stability in the abnormal phoria group decreased in the order: KDE (±1 SD), BCEA (±1 SD), KDE (±2 SD)/Scanpath, and BCEA (±2 SD).
• BCEA tended to overestimate fixation area, while KDE tended to underestimate it at high densities.
• The Scanpath method produced a large area encompassing all gaze points.

Conclusions:

• Fixation stability can be reliably quantified using image-based areas calculated by KDE, BCEA, and Scanpath methods.
• The choice of method may influence the perceived stability, suggesting that a combination of methods could provide a comprehensive evaluation.