Barker, Felix OD, MS, FAAO; Cockerham, Glenn MD; Goodrich, Gregory PhD, FAAO; Hartwick, Andrew OD, PhD, FAAO; Kardon, Randy MD, PhD; Mick, Andrew B. OD, FAAO; Swanson, Mark OD, MSPH, FAAO

Public awareness of brain injury has been heightened by two seemingly unrelated factors: brain injury in military personnel during the recent wars in Afghanistan and Iraq and sports-related concussions. The former has resulted in over 340,000 military personnel sustaining a brain injury¹ and the latter some 170,000 head injuries per year from sports participation in children age 19 and younger.² The consequences of even mild traumatic brain (concussion) injury are complex and may include cognitive, memory, emotion, motor, and sensory functions. Visual function is often overlooked in diagnosing brain injury symptoms, as it is not readily visible to the non-ophthalmic clinician with visual symptoms being confused with other symptoms. For example, an individual scoring poorly on (visual) neuropsychological assessments may be labeled as having cognitive problems. This being the case whether or not the cause is cognitive, visual, or both, simply because these were developed as assessments of cognitive function even though many aspects of the test require intact visual function.

The frequency of brain injuries in both military and sports arenas also seem different because a different terminology is used to describe the injury. Service personnel are diagnosed with some severity of brain injury whereas athletes are typically diagnosed with concussion. The general consensus is a concussion and mild traumatic brain injury (mTBI) are not different. However, there is little consensus on the use of the term mTBI in sports with some advocating that its use needlessly scares parents or children. Most concussions/mTBI cases do resolve without lasting impact, with the possible exception of increased severity when there are subsequent concussions. Others may argue that using the term concussion understates potential harm and may reduce the likelihood that the individual will receive an assessment to determine if the concussion requires treatment.

The current issue of Optometry and Vision Science is exciting, as our contributors provide new information that better informs us about visual consequences of brain injury. Also, in doing so, it improves our overall understanding of the consequences of brain injury. The issue takes a very broad view of the visual ramifications of brain injury and addresses critical topics including assessment, diagnosis, and treatment.

The first paper addresses the difference in visual symptoms between military and civilian brain injury. Capo-Aponte and colleagues describe visual dysfunctions in Warfighters who sustained brain injury from either a blast event or non-blast event.³ Although both causal mechanisms resulted in high rates of visual symptoms and dysfunction, the type and rate of visual findings were not different in terms of visual sequelae. This is important because it suggests that what is learned from research into visual deficits from military blast events is applicable to injury from non-blast events that are typical of civilian injuries. Also, of course, what is learned from civilian injuries may be applicable to military injury.

Jorkasky and Goodrich expand the link between military and civilian similarities in visual sequelae in an invited perspective.⁴ They review successful efforts to increase Congressionally directed funding and highlight the roles of advocacy groups, news media, research, and testimony by individuals who have sustained brain injury-related vision loss. They further argue that maintaining and increasing vision research funding will depend upon continuing the efforts of “every voice” to educate Congress on the need for further research funding. The value of such Congressional funding is apparent in that many of the papers contained in this issue would not have been possible without such funding.

D’Surney and colleagues report on counterintuitive research findings in the use of erythropoietin (EPO) as a therapeutic agent to protect the retina after blast injury.⁵ Their results suggest that EPO, at least in mice, may be effective and that delivery of EPO is not time critical. Indeed, EPO may be protective of retinal neurons and axons if intraocular EPO is given 3 weeks post-injury, not at time of injury.

Considerable media attention has been given to chronic traumatic encephalopathy, commonly known as CTE. CTE is a neurodegenerative disorder linked to multiple concussive events. Although the untimely deaths of many well-known professional football players have garnered much of the media attention, other sports including boxing, hockey, and wrestling have been linked to CTE. Armstrong and colleagues report that neuronal loss in the superior colliculus may be a consistent feature of CTE.⁶ Given the role of the superior colliculus in eye movements, their study suggests that eye movement dysfunctions are a possible clinical symptom present in individuals with CTE. If proven to be the case, eye movements may be useful as part of an in vivo screen for CTE.

Given the widespread incidence and the variety of possible symptoms after brain injury, there is growing recognition that assessments of visual deficits need tools that can be conducted easily and accurately by health care providers. Laukkanen and colleagues describe the Brain Injury Vision Symptom Survey (BIVSS)—a symptom survey designed to assist health care providers document vision complaints in adults with mild to moderate brain injury.⁷ The authors report a controlled validation study of the BIVSS. To spur further research and utilization of the instrument, the authors are generously making the survey available at no cost. Taking a different path to assessment of vision deficits after brain injury, Liston and colleagues report on a controlled study using eye-movement testing to detect sensorimotor deficits associated with TBI.⁸ The test employs randomized, radial tracking tasks that the authors report as providing a sensitive screen useful for quantifying functional impairment, monitoring deterioration or recovery, and evaluating treatment effectiveness.

The growing concern about concussions in student athletes has led to the development of widely accepted “return-to-play” criteria. These criteria are useful in guiding parents, coaches, trainers, and others in limiting a player’s return-to-play so as to maximize the body’s ability to heal from a concussive event. “Return-to-learn” criteria, focusing on readiness to return to school after a concussive event, are widely acknowledged as needed. Perhaps because concussions often occur in athletics, criteria to determine if a player can stay in the game and/or safely return to the sport receive greater attention than return-to-learn criteria. The latter criteria concern when a player should return to school; despite evidence linking vision and academic performance, these criteria seldom include vision assessment. Swanson and colleagues report, in a retrospective study, that vision symptoms were commonly reported in children with concussion, as were reports of academic difficulty.⁹ The authors present a compelling argument that vision assessment should be considered both for children reporting academic difficulty and in future development of return-to-learn criteria.

The determination of a vision problem after concussion raises the question of how to treat the problem. Gallaway and colleagues used a case series methodology to address this question.¹⁰ Most patients included in their review exhibited vision problems with convergence and accommodative insufficiency being the most common. Treatments provided to address the symptoms showed a statistically significant improvement in reducing or eliminating them. The authors state that prospective clinical trials are needed to characterize the natural history of concussion-related vision disorders and treatment. Furthering the treatment of vision problems after concussion, Scheiman and colleagues prospectively studied office-based therapy with home reinforcement in the treatment of convergence insufficiency using change in disparity vergence as a treatment outcome measure.¹¹ The authors suggest that these measures could be used as outcome measures in future randomized trials for treatment of convergence insufficiency.

Concussion can occur across all ages; however, diagnosis of concussion in children has not received sufficient attention. Noting this, Weise and her colleagues studied the short-term repeatability of the King-Devick Test in a large group of school-age athletes who received screenings pre-season.¹² Their data indicate that the test is applicable to school-age children, although they note that repeat measurement variability became less with increasing age. They also report that the test can be applied for mass screening in a school setting. Of note is their finding that within-subject comparison to their own baseline may provide the best method for making removal-from-play decisions.

Furthering our understanding of concussive effects on vision, Storey and her colleagues report a cohort of pediatric patients post-concussion.¹³ In this cohort, abnormal near point of convergence was found in about one child in four. Of this subset, just under half had clinically normal findings by 4.5 weeks post-injury and most recovered within 11 weeks post-concussion. Over 10% had persistent symptoms and were referred for vision therapy. The authors hypothesize that near point of convergence should be considered in post-concussion examinations as it addresses symptoms that may not be identified through questionnaire screenings.

Kulp and colleagues¹⁴ evaluated the effectiveness of home-based computer vergence therapy in the treatment of binocular vision disorders in adults who were treated at least 3 months post-brain injury. They assessed a variety of binocular dysfunction measures including fusional vergence, near point of convergence, and vergence facility. After a 12-week, home-based computer vergence therapy regimen, most patients who completed the training experienced meaningful improvements in signs and symptoms. The authors feel their study supports the need for placebo-controlled, clinical trials to determine the best treatment for common binocular vision conditions that occur after brain injury.

Photophobia is a common symptom after brain injury; however, the causal physiological mechanism is not well understood. Yuhas and colleagues¹⁵ compared pupillary responses to blue and red light in mild traumatic brain injured and control subjects’ pupillary responses to blue and red light. Their results did not support the hypothesis of hypersensitivity to light, but do show greater response variability in subjects with brain injury compared to controls. The study promotes the understanding of the underlying causes of photophobia post-brain injury and contributes to development of treatments based upon objective research.

This issue concludes with two important reports that pose interesting questions relevant to research and clinical practice. The first by Houston and Barrett is a review of the existing literature on the effect of patching for double vision.¹⁶ They discuss possible effects of this treatment in patients who experience double vision after a brain injury. Patching is commonly used to treat double vision in strabismic patients when prisms are not feasible. The authors found the literature on patching, in cases of neglect and double vision after brain injury, may not be wise because of the interaction of patching and neglect. Houston and Barrett feel the literature supports the use of partial occlusion rather than the use of a patch.

Vien and colleagues¹⁷ report an interesting case study of an individual with transsynaptic retrograde degeneration of the retinal nerve fiber layer. Using spectral-domain optical coherence tomography, they found their 25-year-old patient experienced retinal nerve fiber degeneration over a 2-month time post-brain injury. The timeline Vien found was shorter than expected based on previous clinical observations. They further note that visual field may improve over time; however, the improvement may not correspond to nerve fiber losses noted by spectral-domain optical coherence tomography.

The guest editors wish to thank the authors, reviewers, and OVS editors and staff for contributing their time and expertise.

Felix Barker, OD, MS, FAAO

Rock Hill, South Carolina

Glenn Cockerham, MD

Palo Alto, California

Gregory Goodrich, PhD, FAAO

Union City, California

Andrew Hartwick, OD, PhD, FAAO

Columbus, Ohio

Randy Kardon, MD, PhD

Iowa City, Iowa

Andrew B. Mick, OD, FAAO

San Francisco, California

Mark Swanson, OD, MSPH, FAAO

Birmingham, Alabama

REFERENCES