Ocular-Motor System Vulnerable to Cumulative Sub-Concussion Injuries

MedicalResearch.com Interview with:

Dr. T. Dianne Langford PhD Associate Professor, Neuroscience and Neurovirology Lewis Katz School of Medicine Temple University

Dr. T. Dianne Langford

Dr. T. Dianne Langford PhD
Associate Professor, Neuroscience and Neurovirology
Lewis Katz School of Medicine
Temple University

MedicalResearch.com: What is the background for this study?

Dr. Langford: The ocular-motor system has been shown to reflect neural damage, and one of ocular-motor functions, near point of convergence (NPC), was reported to worsen after a sport-related concussion (Mucha et al. Am J Sport Med). But the effects of subconcussive head impact, a milder form of head injury in the absence of outward symptoms remains unknown.  Prior to this study, we found that in a controlled soccer heading experimental paradigm decreased NPC function, and even 24h after the headings, NPC was not normalized back to baseline (Kawata et al. 2016 Int J Sport Med). To extend our findings from the human laboratory study, we launched longitudinal clinical studies in collaboration with the Temple football team, to see if repetitive exposure to subconcussive head impacts negatively affects NPC.

MedicalResearch.com: What are the main findings?

Dr. Langford: We categorized football players into lower and higher impact groups, based on frequencies and magnitudes of head impacts sustained as measured by an accelerometer-embedded mouthguard. We found that while NPC in the lower impact group remained consistent throughout the study duration with no changes, the higher impact group started to show defects after the 1st full contact practice, and the deficiency did not resolve to baseline during the study duration, but normalized only after 3 weeks rest at post-season follow-up.

MedicalResearch.com: What should readers take away from your report?

Dr. Langford: The ocular-motor system is vulnerable to even mild head impacts, if sustained repetitively. Also, NPC showed slow recovery after subconcussive head impacts, which are in line with the soccer heading study. This measurement illustrates the cumulative changes in NPC after head impact, even in the absence of outward symptoms.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Dr. Langford: The next step is to decipher the potential threshold between repetitive subconcussive impacts and a concussion. After a concussion, a previous report shows that NPC being worsened by 3 fold (Mucha et al. Am J Sport Med), but after subconcussion we observed a change of 30 to 40%. Larger scale longitudinal studies designed to follow players long-term to see if there is a pattern between cumulative burden and subconcussive blows are warranted.    

MedicalResearch.com: Is there anything else you would like to add?

 Dr. Langford: To understand concussion, collaborative efforts from different disciplines are extremely important. We would like to thank coaches and players who helped us complete this study. This study is still at its an initial step to uncover the complex phenomenon of concussion and subconcussion and to protect the player and the game.  

MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.


Kawata K, Rubin LH, Lee J, et al. Association of Football Subconcussive Head Impacts With Ocular Near Point of Convergence.JAMA Ophthalmol. Published online May 12, 2016. doi:10.1001/jamaophthalmol.2016.1085.

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Last Updated on May 12, 2016 by Marie Benz MD FAAD