Sex differences in fixational eye movements following concussion

Area of Science:

• Neuroscience
• Ophthalmology
• Sports Medicine

Background:

• Fixational eye movements (FEMs) are increasingly recognized as objective biomarkers for concussion.
• Previous studies suggest larger fixational saccades post-concussion, but sex-based differences remain unexplored.

Purpose of the Study:

• To investigate sex differences in FEMs and fixational saccades in adolescents with concussion.
• To evaluate the reliability of FEMs as a concussion biomarker considering task and sex variations.

Main Methods:

• Utilized retinal image-based eye tracking with a tracking scanning laser ophthalmoscope (TSLO) to record FEMs.
• Employed an objective velocity-based algorithm for reliable detection of fixational saccades.
• Recruited adolescents with concussion (n=44) and age/sex-matched healthy controls (n=44).

Main Results:

• Concussion patients exhibited larger fixational saccades than controls, specifically during center fixation tasks.
• Females, regardless of concussion status, displayed larger fixational saccades than males on the center task.
• Sex differences emerged in saccade characteristics on the corner task: females had fewer horizontal and more oblique saccades than males.

Conclusions:

• Fixational saccade size is influenced by both concussion and sex, particularly during center fixation tasks.
• Task and sex must be carefully controlled for when interpreting FEMs as a concussion biomarker.
• These findings underscore the complexity of FEMs and their potential for nuanced concussion assessment.