Sports-related concussion (SRC), also called mild traumatic brain injury, accounts for approximately 20% of all traumatic brain injuries.¹ (See sidebar: “SRC: An Overview.”) Often, those who have an SRC report convergence insufficiency, accommodative dysfunction, saccadic dysfunction, photosensitivity, peripheral motion sensitivity, abnormal egocentric localization (a shift in perception of midline), and deficits in visual information processing.2,3 Given these vision-related symptoms, the OD can play vital roles in identifying and managing SRC. Here, I discuss these roles.
Identifying SRC
An SRC assessment is comprised of a systematic review of symptoms, behavioral changes, physical signs, cognitive impairments, sleep disturbances, and vision/balance disorders.4 SRC assessment can be challenging, as there are a variety of signs and effects. Thus, the optometrist should plan for extra time or multiple visits with these patients. The following recent advancements can assist with the assessment:
• The Brain Injury Vision Symptom Survey (BIVSS). This is a 28-item scaled questionnaire that provides a validated, reliable, comprehensive symptom assessment covering 8 categories: eyesight clarity, visual comfort, doubling, light sensitivity, dry eyes, depth perception, peripheral vision, and reading.5 The BIVSS (http://bit.ly/4mhcfWS) has shown good test-retest reliability,6 and has validity for identifying SRC.5
• Pupillometry. Quantitative pupillometry has shown measurable changes in the size and reactivity of the pupils in SRC.7,8 Specifically, these metrics have been found significantly different in SRC: maximum and minimum pupillary diameter, peak and average constriction/dilation velocity, percentage constriction, and time to 75% pupillary redilation.
• Automated eye tracking instrumentation. This is an objective method for potentially detecting oculomotor abnormalities and may be less prone to the challenges of subjective response assessments.9 Objective eye tracking shows that smooth pursuit and saccade metrics are significantly different in those who have a recent concussion.10-13 Also, studies reveal significant differences in accommodative and vergence function in those who have a history of concussion.3,14,15
• Scanning laser ophthalmoscope. Fixational eye movements are significantly different in those who have diagnosed symptomatic concussion within the past 21 days when compared to healthy age/gender-matched controls.16
• The vestibular/ocular motor screening (VOMS) assessment. This evaluates vestibulo-ocular function through a subjective rating of increases in symptoms of dizziness, nausea, and fogginess. It is comprised of brief assessments of smooth pursuit eye movements, horizontal and vertical saccadic eye movements, convergence, horizontal and vertical vestibular ocular reflex, and visual motion sensitivity. The portion of the VOMS that assesses convergence (nearpoint of convergence repeated 3 times) appears particularly sensitive in detecting concussion. A caveat: symptom provocation when performing VOMS assessments may be associated with longer recovery times.17,18
The VOMS assesses whether performing these procedures provokes symptoms, so no steps are taken to reduce symptoms during assessment.
• The Gaze Stability Test (GST). This determines the maximum head velocity that a displayed optotype can be accurately identified. GST velocity and asymmetry values provide objective data about impairment and progress in recovery within the vestibular domain.19
Managing SRC
A thorough review of the many treatment options is beyond this article’s scope. Here is a short overview:
• Prism options. An athlete may be more sensitive to small phorias following SRC, especially vertical phorias. Therefore, small prismatic correction, even 1.00 D to 2.00 D may improve visual symptoms during their recovery period. In patients who have diplopia, prism, occlusion, or a monovision correction may minimize symptoms. Something to keep in mind: vision therapy designed to improve oculomotor function is shown to assist in concussion recovery and may be effective in reducing the need for prismatic correction.20,21 For more on vision therapy, I recommend “Clinical Management of Binocular Vision, 5th Edition.”
Yoked prism (ie, prism with the bases in the same direction, such as bases right) can be helpful for visual field defects, visual neglect/unilateral spatial inattention, or acquired nystagmus. It may also be beneficial for symptoms associated with abnormal egocentric localization, which is an alteration in the self-perception of the “straight-ahead” direction.22 The patient tracks a handheld target moved laterally, then vertically in front of their face at 50 cm, indicating when the target is aligned with their midline.23 Yoked prism can modify the perceptual mismatch of spatial direction and reduce directional mobility and object localization symptoms.
• Filter options. Red (FL-41), yellow (amber), blue, gray (neutral), and photochromic filters, can reduce photosensitivity symptoms. (I have found that sunglasses may only decrease symptoms outdoors.)
My advice: Start with the patient’s filter choice. Then determine the optimal light transmission density. Prescribing a lighter tint density may support adaptation to photosensitivity symptoms over a longer duration.24 Filters may also help with common symptoms of visual motion sensitivity: an inability to tolerate visually busy places, avoiding crowds, and instability and nausea when walking due to peripheral vision flow.
• Ocular nutritional supplementation. Supplementation with zeaxanthin and lutein is shown to improve sensitivity to bright light (glare discomfort), glare disability, and slowed photostress recovery.25
• Binasal occlusion. This is shown to improve visual motion sensitivity symptoms.26,27 Specifically, it appears to increase visual-evoked potential (VEP) amplitude in SRC. This corresponds to symptom improvements.
• Neurovisual rehabilitation. This may include pursuit and saccadic eye movement patterns (progressing from suppine to sitting, standing, and then balancing), a near-far “rock” to introduce convergence demand, and use of yoked prism to “load” the demands. Studies show the efficacy of this rehabilitation for the treatment of binocular vision conditions following traumatic brain injury, and many aspects of it reveal improvements using objective assessment measures.21,28,29
Neurovisual rehabilitation may also be designed to address acquired visual information-processing and perception deficits. For example, initial studies suggest that low-level light therapy may modulate recovery in traumatic brain injury patients by improving functional connectivity on resting-state neuronal circuits.28
For hyperopic athletes, added plus lenses at near may be indicated due to the increased likelihood of accommodative dysfunction following SRC. Also, prescribing unequal near addition lenses may be necessary due to unequal effects on accommodation. These modifications may be temporary during the recovery period. Recovery time can vary a lot. I, personally, counsel these patients to slowly work toward a normal routine but to plan for frequent breaks or discontinue their routine if symptoms worsen.
SRC: An Overview
SRC is highest in American football and ice hockey for males, and soccer and lacrosse for female athletes.30-32 It is often caused by a blunt head trauma that can involve acceleration or deceleration forces creating the initial tissue damage and resulting ischemia. The tissue damage in SRC can diminish brain metabolism and affect cerebral blood flow regulation, which is the initial phase in the pathophysiology of traumatic brain injury.
The secondary phase involves the development of cytotoxic (intracellular) and/or vasogenic (interstitial) edema, which can ultimately cause elevated intracranial pressure and further damage. Edema in the brain is commonly worse 24 to 48 hours following the injury, with sustained inflammatory responses that affect metabolic regulation and disruption of cerebral vascular function.
The common symptoms of SRC include loss of consciousness, amnesia, headache, confusion, disorientation, dizziness, fatigue, “fogginess,” visual disturbance, sleep disturbance, and nausea. A greater number and severity of symptoms, especially of prolonged headache or concentration problems, has been associated with a longer recovery period before returning to sport.33
A Vital Member
Visual sequelae of SRC are common, so the optometrist’s expertise in treating this element of recovery is an important component of multidisciplinary management. OM
References
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