A History of Concussion Does Not Lead to an Increase in Ocular Near Point of Convergence

Abstract

Ocular near point of convergence (NPC) has been shown to be sensitive to the effects of concussion and subconcussive impacts. To determine if NPC is also sensitive to a previous history of concussion, male contact-sport athletes either with (n=26) or without (n=16) a history of at least one previous concussion had their NPC assessed. The results showed that participants with a history of concussion displayed NPC values (9.4±1.6 cm) indistinguishable from those with no history of concussion (8.4±2.1 cm, t-test, p=0.09). This was the case regardless of whether 1, 2, or 3 or more concussions had occurred and despite the fact participants with concussion (mean time since last concussion: 1136 days) suffered from an increased number and severity of symptoms as assessed with the SCAT 3 (3.6±2.2 vs. 2.13±1.89 symptoms, 6.1±4.1 vs. 3.19±2.99 severity, t-test, p<0.05). Taken together, these results imply that NPC may not be a suitable tool to assess the potential long-term effects of one or more concussions over a longer time frame.: Future research using larger sample sizes is warranted to evaluate the potential dose-response relationship between number of prior concussions and NPC.

Longitudinal Vestibular and Oculomotor Impairments Among Amateur Athletes 1 Year Following Sport-Related Concussion: A Prospective Follow-Up

“…Although NPC distance is infrequently investigated in the long term following concussion, one study demonstrated that student-athletes with a history of concussion (>6 months) exhibited similar NPC distance compared with a control group without a concussion history. 42 In addition, rates of receded NPC (>5 cm) in our concussion group approximated the proportion of athletes in other studies who exhibit receded NPC acutely and subacutely following concussion (36%-50%). 12,14,27,32,35 The rates of receded NPC (>5 cm) in the control group at the 6-month (30%) and 1-year (32%) study assessments fall within the range (11%-33%) of receded NPC (>5 cm) proportions observed across studies evaluating healthy, nonconcussed athletes.…”

“…These findings align with prior studies investigating NPC distance in concussed and control athletes following sport-related concussion. Although NPC distance is infrequently investigated in the long term following concussion, one study demonstrated that student-athletes with a history of concussion (>6 months) exhibited similar NPC distance compared with a control group without a concussion history 42. In addition, rates of receded NPC (>5 cm) in our concussion group approximated the proportion of athletes in other studies who exhibit receded NPC acutely and subacutely following concussion (36%-50%) 12,14,27,32,35.…”

Assessing Brain Processing Deficits Using Neuropsychological and Vision-Specific Tests for Concussion

“…A history of one or more prior concussions increases the odds 5.8 times of sustaining another concussion [34,36]. However, a history of concussion does not result in poorer performance on the NPC [58] or the K-D test [10] in isolation. Therefore, combining both visual assessment metrics while considering age in those with and without a history of concussion might better identify those who have sustained a concussion.…”

“…Pearce et al showed differences in NPC between concussed and non-concussed athletes (12.6 ± 9.0 vs. 1.5 ± 1.5) [48]. van Donkelaar et al identified that NPC did not adequately discriminate between those with and without a concussion history (9.4 ± 1.6 vs. 8.4 ± 2.1 cm) [58]. Del Rossi reported that about 20% of the NPC were below the cut-off of ≥5 cm, leading to incorrect categorization, while there was no association between NPC and a concussion history despite better NPC in those with a history of concussion [62].…”