Computational protocol: Using Eye Tracking to Assess Reading Performance in Patients with Glaucoma: A Within-Person Study

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Protocol publication

[…] A linear mixed effects ANOVA was performed in R [] using the linear and nonlinear mixed effects models (nlme) package to assess differences in the average reading duration and saccade rate between patients' worse and better eyes. A mixed effects model was chosen since different sentences were viewed by the worse and better eye. The random effect was set as the patient. The ANOVA was performed to test the null hypothesis, for each response, that the means for the patients' worse and better eyes are the same.For each eye we also calculated the percentage of eye movements that were automatically classed as the four types of saccade by the classification algorithm, namely, “forward saccades,” “regressions (backwards saccades),” “between line (line change) saccades,” and “unknown” across the 50 trials read by the better and worse eye, respectively. Statistical differences in these proportions between the worse and better eye were then assessed (Wilcoxon's test).To investigate whether the magnitudes of the change in the key measured variables between eyes for each person were important, we next calculated the difference between eyes for reading duration and saccade rate (worse eye minus better eye) to create novel “change” variables for each person. The differences between the worse and better eye were also calculated for all the measured visual function parameters (i.e., change in VF severity, VA, and CS between eyes) and then each of these resulting variables was compared to the changes in reading duration and saccade rate between eyes. Therefore, it could be determined whether larger reductions in visual field defect severity, contrast sensitivity, or visual acuity were related to a greater change in reading duration or eye movement behaviour when reading with the worse eye compared to the better eye.Finally, differences in the median values for each of the identified eye movement types between the worse and better eye were calculated for each person; these were then compared to the change in reading duration per trial and saccade rate between eyes. Statistically significant associations were tested for using Spearman's rank correlation (rho) and also using R []. […]

Pipeline specifications

Software tools lme4, nlme
Application Mathematical modeling
Diseases Glaucoma, Ocular Motility Disorders