Abstract
Purpose :
The pupillary light reflex (PLR) has evaluated as a potential marker of subtle neurological impairment in sports related concussion. The PLR is known to be affected by arousal state. Greater degrees of pupil dilation are seen with increasing cognitive load. The purpose of this project was to assess the effect of a low level cognitive tasking on the kinetics of the PLR in collegiate athletes.
Methods :
A cohort of 34 collegiate athletes (25 male football players and 9 female soccer players) at the University of Alabama at Birmingham were recruited to participate. All athletes were competing in their athletic season during testing. Subjects were tested within an area within the student athletic complex. PRL was measured independently in each eye using the NeurOptics NPi-200. This infrared pupillometer records a three second video with output including seven measures of pupil size and kinetics. Each test session consisted of two untasked and two tasked measures. Cognitive tasking consisted of serial subtraction by five. After two subtractions PRL was measured. General linear models were used to assess the effect of tasking and sport on pupil parameters.
Results :
No differences in the tasked and untasked pupil response was seen for NPi index, pupil initial size, minimum size, percent constriction, constriction latency and dilation velocity in either eye. Both the average constriction velocity (OD p<.001, OS p=.014) and maximum constriction velocity (OD p<.001, OS p=.014) were slower in the tasked versus untasked pupil testing. Average constriction velocities were 0.24 and 0.18 mm/s slower OD and OS respectively for the cognitive tasked pupil response. Maximum constriction velocities were similarly reduced (OD 0.29, 0.25 OS mm/s) during the tasked testing. The sport the athletes participated in did not interact with any of the parameters, but was independently associated with constriction latency. Football player’s response latency was 0.0126 and 0.0141 seconds slower OD and OS respectively.
Conclusions :
Low level cognitive loading did not affect initial pupil size in this cohort of collegiate athletes as might have been expected. Cognitive loading did however affect response dynamics velocity. This suggests that athletes pupil responses should be tested in similar cognitive circumstances as well as physical ones if they are to be compared to baselines.
This is a 2020 ARVO Annual Meeting abstract.