The relationship between concussive and subconcussive head impacts and ocular motor abnormalities (eg, near point of convergence [NPC]) is an interesting, timely, and somewhat controversial area of study. The topic has broader implications for other non–sports-related head trauma, particularly military (eg, blast-related traumatic brain injury) and nonmilitary-related head injuries. There are also potential medicolegal and medical reasons for studying this important topic.
In this issue of JAMA Ophthalmology, Kawata et al1 investigated whether subconcussive head impacts during preseason football practice were related to any acute or subacute changes in ocular NPC. The strength of this report is the prospective, longitudinal observational study design in 29 National Collegiate Athletic Association Division I collegiate football players including baseline, preseason practices (1 noncontact [pads off, helmet only] and 4 contact [pads on, full gear]), and postseason follow-up. Near point of convergence measurements and player symptom scores were obtained at the defined time points immediately before and after practice. An accelerometer-embedded mouthguard was used to measure impact kinematics in a standardized, reliable, and reproducible manner. The football players were then categorized into “lower” (n = 7) or “higher” impact (n = 22) groups. In the “higher-impact” group, there was a significant linear increase (worsening) in NPC scores compared with the first pads-on practice. However, this effect plateaued and then resolved by the postseason follow-up, suggesting a real but transient effect on NPC. In contrast, in the “lower-impact” group, there was no change in NPC over time. This information should be somewhat reassuring, but it requires further longitudinal study in a larger cohort of athletes.
Lee AG, Galetta SL. Subconcussive Head Trauma and Near Point of Convergence. JAMA Ophthalmol. 2016;134(7):770-771. doi:10.1001/jamaophthalmol.2016.1360