Football-related concussions and head impacts are associated with changes in retinal structure and signaling

Subconcussive head hits (SHH) are common in contact sport athletes and are predictive of the later development of cognitive and brain changes, including chronic traumatic encephalopathy. In this pilot study we determined whether a history of concussion, and SHH acquired during a single season of college football, were associated with changes on retinal biomarkers of central nervous system (CNS) structure and function. College football players with a history of concussion (FB+C; n=9) or without a concussion history (FB-C; n=11), and non-contact sport collegiate athletes (Track/Swim; n=12) underwent visual and cognitive testing, retinal imaging (optical coherence tomography (OCT) and OCT angiography (OCTA)), and electroretinography (ERG) at three time points: pre-season, post-season and 4-month follow-up. The FB+C group demonstrated thicker maculae and exaggerated ERG waveforms (from all retinal neural cell types) compared to the other groups. These changes were generally observed at all timepoints, suggesting long-term changes associated with concussions, rather than effects of recent football activity. However, we also observed significant relationships between the number of head impacts during the season and stronger ERG responses, degree of macula thickening, enlargement of optic disc parameters, and increases in the density of retinal microvasculature relative to controls. These data suggest that retinal biomarkers are sensitive to both long- and short-term CNS changes related to participation in football, even in young athletes.