Retinal and Balance Changes Based on Concussion History: A Study of Division 1 Football Players

Abstract

Background: The long term effects of a sports concussion or mild traumatic brain injury (mTBI) is poorly understood. The term chronic traumatic encephalopathy (CTE) is associated with protein deposition observed post mortem; thus the diagnosis of CTE in living subjects is impracticable using protein deposition as a diagnostic criterion. To date, there is no validated, objective method to observe and document pathologic changes post mTBI. The brain, optic-nerve, retina axes is closely linked; it is believed that some aspects of mTBI may be reflected in the retinal nerve fiber layer (RNFL) and that optical coherence tomography (OCT) could be a means to observe and document these changes. In this paper we show an association between a history of concussion and RNFL changes in college athletes. Methods: Each member of the University of Cincinnati football team was surveyed for a history of diagnosed concussion during pre-season camp. All players participating in camp were consented and were subjected to both a retinal exam using the Optovue iVue OCT retinal imaging system and a balance challenge by performing a visual motor task (Dynavision D2) on a BOSU Pro Balance Trainer (BOSU ball) and on a firm surface. Eye-hand coordination, balance and RNFL thickness measurements for the athletes with a history of concussion were compared to those the athletes with no history of concussion. Results: A total of 34 athletes reported having at least one previously diagnosed concussion that occurred up to 10 years prior to data collection; 73 reported no history of diagnosed concussion. Data analysis of the OCT retinal images demonstrated significant thickening of the RNFL in those athletes with a remote history of concussion when compared to athletes with no history of concussion, 106.8 μm vs 103.7 μm (p = 0.009), respectively. With the BOSU ball challenge there was no change in performance with or without a balance challenge 4.57 vs 4.63 hits per minute (p=0.93) for those with history of concussion versus no history. The performance task on the Dynavision D2 is an eye hand coordination task and a balance task, so eye hand coordination was not impacted by the RNFL changes. Discussion: In this paper we report significant sustained chronic RNFL thickness changes occurring in athletes with a remote history of concussion when compared to similar athletes without a reported history of concussion. However, there were no statistically significant sustained changes in eye hand coordination or balance challenge performance tasks. We suggest that RNFL changes may be an indicator of a structural brain injury following a postconcussive eve