Worldwide traumatic brain injury (TBI) is identified as a major cause of morbidity and mortality and it also has considerable socio-economic consequences. Traumatic brain injury is a form of acquired brain injury that is a nondegenerative, noncongenital insult to the brain from an external (mechanical) force, possibly leading to permanent or temporary impairment of cognitive, physical, and psychosocial functions, with an associated diminished or altered state of consciousness.
The most widely used clinical scoring method to assess the level of consciousness and severity of the brain injury is the Glasgow Coma Scale (GCS) and is based on three parameters; motor responsiveness, verbal performance, and eye opening to an appropriate stimulus. The total score ranges from a minimum of 3 to a maximum score of 15, a patient with a score of 3 through 8 is classified as a severe TBI, 9 through 12 as a moderate TBI and 1 through 15 as a mild TBI (Teasdale et al., 2014).
In Europe, every year 263 people in every 100.000 people in the population suffer from a traumatic brain injury (TBI), for the Netherlands the incidence is 213.6 per 100,000 people per year. In the United States the number for TBI related hospital visits in 2014 were approximately 2.87 million (Peeters et al., 2015; Peterson, 2019; Scholten et al., 2014). Mild traumatic brain injury, commonly referred to as concussion, approximately make up for 70% to 80% of all TBI’s. It’s incidence is higher in males (Georges & Booker, 2020; Nguyen et al., 2016).
Because of the various brain pathways, cortical areas and cranial nerves involved in vision, the visual systems are particularly vulnerable to the effects of TBI. The most common visual symptoms in acquired brain injury (ABI) including mild traumatic brain injury (mTBI) are headaches, dizziness, blurred vision, photophobia, loss of balance, eyestrain, visual field defects, visual information processing problems, dry eye symptoms and defects involving visual perception, motion vision and visuo-spatial function (Armstrong, 2018; Simpson-Jones & Hunt, 2019).
According to research, up to 90% of people with TBI experience oculomotor dysfunction (Ciuffreda et al., 2007). There are various allied health professionals that address and provide vision rehabilitation for these functional visual deficits known as post mild TBI related symptoms, such as optometrists, occupational therapists, physiotherapists and chiropractors (Blanchard et al., 2016; Hudac et al., 2012; Olson et al., 2016; Padula & Argyris, 1996).
The main objective of this article is to review the scope of rehabilitation interventions for patients with visual dysfunctions following their mild traumatic brain injury and to document the different methods and the different professions that provide these treatment options.
Material and Methods
To obtain the research to answer my research question of “What kind of vision rehabilitation interventions are there for patients following mild traumatic brain injury?” the following electronic databases were used: PubMed, Science Direct and Google Scholar, as well as information obtained from book chapters and conference presentations.
To begin the search for relevant information on the research question, the following subject searches were used: “traumatic brain injury” and “vision or visual” and “rehabilitation or therapy or intervention” in the database search engines. As a result of the data acquired from these subject searches the following key words were used:
Ocular motility disorders
Traumatic brain injury
Vision interventions/brain injury
Visual dysfunctions/brain injury
Functional medicine/traumatic brain injury
Vision/light therapy/ traumatic brain injury
Traumatic brain injury/chiropractic
Traumatic brain injury/optometry
Traumatic brain injury multidisciplinary
Head injury vision rehabilitation
Vision/occupational therapist/brain injury
Brain Injuries / rehabilitation
Also, any articles, book chapters and other materials that were referenced in the articles found were reviewed to determine if they were to be included or excluded as references for this article.
The criteria for the inclusion of the found research materials was that they addressed treatment of visual deficits in patients with mild traumatic brain injury. Articles or other forms of reference material that didn’t include these parameters were excluded. Included were articles containing a study population with a history of mild traumatic brain injury or concussion and the inclusion of a vision rehabilitation plan. The visual skills assessed in the articles we included were: acuity, visual field, oculomotor control and ambient visual processing.
Interventions that were excluded contained patients with brain injury due to stroke and other brain injuries caused by internal influences.
The database search identified 4,087 articles/records, after eliminating the double references and excluding the articles that didn’t meet the criteria for full text review, this included hand searching information for conference and books, resulted in 25 articles that met the inclusion criteria for the final review. The studies included in the review were published between 1996 and 2017.
They included research or case-studies that assessed vision therapy or evaluated optical devices which included one or more of the following: binasal occlusion, yoked prisms, or corrective spectacles. Also, more holistic or alternative methods of intervention were examined. For instance, light therapy, a hyperbaric chamber and a case review of chiropractic intervention.
A case study by Caldwell & Reyes-Cabrera (2015) of a 24 year old female soldier presented with a history of at least one concussive event and complains that were characteristic of Post Trauma Vision Syndrome (PTVS; Table1). They conducted a full ocular health exam and neuro optometric evaluation and diagnosed her with convergence insufficiency and Visual Midline Shift Syndrome (VMSS; Table 2).
Table 1: Characteristics and symptoms of Post Trauma Vision Syndrome (Padula & Argyris, 1996)
Blurred near vision
Perceived movement of print or stationary objects
Table 2: Symptoms of Visual Midline Shift Syndrome (Padula & Argyris, 1996)
Poor or altered posture
Poor or decreased balance
Altered gait or sense of drifting while walking; “tilted floor” phenomenon
Less commonly, vertigo
Less commonly, spatial disorientation in complex visual environments
They first issued corrective spectacles for distance, one pair with 15% grey tint, and one clear. For the convergence insufficiency they provided a pair of spectacles with a add of +1.00 OU and 3^BI OU. They clearly stated that they preferred to have done vision training to correct this problem instead of issuing the glasses; the patient didn’t want to do the vision training. Then the midline shift test was performed and after this test they prescribed spectacles with the prevision distance prescription and 3^ base right OU with photochromatic lenses.
The patient self-reported that she was ‘feeling better” worth the glasses, the patient did not come back for reassessment due to the fact that she wasn’t in the military anymore and was not eligible for re-evaluation at the clinic (Caldwell & Reyes-Cabrera, 2015).
A retrospective analysis by Ciuffreda et al., (2008) explored vision therapy for oculomotor dysfunction in acquired brain injury. They wanted to determine the effectiveness of conventional optometric vision therapy for oculomotor disorders, evaluating patients with mTBI and cerebrovascular accident (CVA). The results were noted separately. In the study there were 33 TBI, mean age 42.3 years with a range 11-66 years and 7 CVA patients, mean age 56.6 years with a range 29-80 years. The conventional optometric vision therapy consisted of vision exercises, computer training and computerized training program for home use to improve vergence, version and accommodation. Accommodation training was only incorporated in the treatment plan for 4 individuals who were younger than 40 years old and manifested an accommodative deficit. The study stated that the criterion for treatment success was denoted by marked total improvement in at least one primary symptom and at least one primary sign. Thirty patients (90%) with TBI and seven patients (100%) with CVA were deemed to have successfully responded to the treatment plan and remained stable after re-testing 2-3 months later. They stated that vision therapy is efficient and that the results showed considerable residual neural plasticity despite the presence of documented brain injury (Ciuffreda et al., 2008).
A study on the effect of binasal occlusion (BNO) on the visually evoked potential (VEP) in visually normal individuals and in those with mTBI by Ciuffreda, Yadav and Ludlam (2013), included 10 subjects that were asymptomatic adults and 10 individuals with mTBI having visual motion sensitivity (VMS) symptoms.
The binasal occluders were made from 38mm transparent lucite disks that fitted into a clinical trial frame and black tape was applied to the front of the surface at a 15° angle (Figure 1). They found that in visually normal adults, the mean VEP amplitude decreased significantly with BNO in all subjects. Whilst the mTBI patients exhibited increased VEP amplitude with BNO compared to the controls and 8 out of 10 of them subjectively reported reduced symptoms and improved visuomotor activities, the two subjects of the mTBI group that disliked the BNO, stated they felt that the BNO blocked the visual field comparable to those that were in the visually normal group (Ciuffreda et al., 2013).
Figure 1. Schematic representation of binasal occluders on a subject (Ciuffreda et al., 2013).
In an alternate therapy study to examine the effects of hyperbaric oxygen (HBO2) on eye tracking abnormalities after mTBI by Cifu et al. (2014), the research population were 60 male military servicemembers with at least one mild traumatic brain injury from combat, confirmed by a TBI specialist, and a mean age of 23.3. No subjects reported any active difficulty with the following vision-related items; blurred vision, light sensitivity and double vision. It was a 10-week single-center, randomized, double-blind, sham-controlled, prospective study at the Naval Medicine Operation Training Center. At each once a day session, the subject breathed either surface air, 100% oxygen at 1.5 ATA, or 100% oxygen at 2.0 ATA for the duration of 1 hour.
To determine if treatment effect existed, the study utilized computerized eye tracking equipment to examine the possible effects of hyperbaric exposure on individuals with mTBI and persistent post concussive syndrome. There were no clinically significant improvements associated with the exposure to the HBO2 (Cifu et al., 2014).
Gallaway, Scheiman & Mitchell (2017) performed a study to determine the frequency and types of vision disorders associated with concussion related symptoms and to determine the success rate of vision therapy for these conditions in two private practice setting that specialize in vision therapy/neuro-optometric rehabilitation. A total of 95 subjects with concussion participated in the study, they had a mean age of 20.5 years, post-concussion vision problems were prevalent and convergence insufficiency and accommodative insufficiency were the most common diagnoses. Vision therapy consisted of once or twice weekly 45 minute in office sessions, for 3-5 days a week 15 minutes of home activities were completed. The vision therapy activities consisted of various vision exercises that utilized the use of optical devices such as loose lenses, prisms, polaroid glasses and computerized vision training (Sanet Vision Integrator and Computer Orthoptics Random Dot Stereogram). Clinically and statistically significant changes were seen in the areas of near point of convergence, positive fusional vergence and convergence insufficiency symptoms, accommodative amplitude and eye movement (Gallaway et al., 2017).
Thiagarajan & Ciuffreda (2014) published an article regarding oculomotor rehabilitation in mild traumatic brain injury. Both studies were a crossover, interventional experimental design of a single blind nature, eight females and four males between the ages of 23 and 33 participated in the discussed studies. In one study they evaluated accommodative parameters in mild TBI before and after oculomotor training. This was a lab-based oculomotor training and a placebo training, which consisted of 6 weeks, two sessions per week, 3 hour of training each. The oculomotor training used computerized exercises to train accommodation (with plus and minus lenses), version and vergence which was done in a clinical setting. Following the oculomotor training, the dynamics of accommodation improved significantly. After the placebo training, none of the measurements were found to have significantly changed (Thiagarajan & Ciuffreda, 2014).
Thiagarajan (2014) also published a study to determine if oculomotor training is effective in individuals with mTBI having oculomotor-based signs and symptoms following their mild traumatic brain injury. The sample size and characteristics were the same as the previous article, this was also a lab-based training program over 6 weeks. Each session was 40 minutes in duration involving 30 minutes of actual training, 15 minutes for horizontal vergence and 15 minutes for accommodation, with rest periods. The training resulted in significant improvements in those with mTBI with intersystem correlation. The researchers concluded that this suggested considerable residual neural visual system plasticity in adults with mTBI. (Thiagarajan, 2014) Clark and Bigsby (2017) published an article in which they assessed if colored glasses mitigate photophobia symptoms in individuals with posttraumatic mild brain injury. This was a cross-sectional study in a rehabilitation clinic, they assessed post-concussion patients for visual symptoms including photophobia and photosensitivity. Off the shelf glasses were used to determine if there were specific colors that provided relief, the test was done using a penlight and multiple pairs of colored glasses. A total of 39 patients had visual symptoms, 76% complained of photophobia and 85% of these patients reported relief of their symptoms while using their colored glasses. Blue, green, red and purple colored glasses provided the most relief (Clark et al., 2017)
A case report by Olson, Tunning & Boesch (2016) described the chiropractic management of a 14-year-old boy with post-concussion syndrome 13 days after his initial injury. The patient experienced occipital headache, upset stomach, blurry vision, nausea, dizziness, balance problems, a “foggy feeling”, difficulty with concentration and memory, fatigue, confusion, drowsiness and irritability. Multimodal manual therapy and chiropractic interventions were used, which included spinal manipulative therapy, myofascial release and instrument-assisted soft tissue mobilization. Additionally, the patient was given exercises to further rehabilitation, this included cervical retraction with superior ocular movement, heel-to-shin walk with the eyes open and closed and sideways crisscross stepping with the eyes open. The patients neurocognitive testing scores improved, the patient didn’t report any symptoms after the treatment plan and was found fit to play (Olson et al., 2016).
In an article on the role of the cervical spine in post-concussion syndrome by Marshall, Vernon, Leddy & Baldwin (2015) presented 5 case reports, 2 of which had visual problems that were co-managed with an optometrist. One of these cases mentioned a 19-year-old male hockey player that sustained a concussion after a car accident. He presented 14 weeks after the accident with frontal headaches, visual problems, concentration difficulties, neck pain, irritability, emotional lability and sleeping difficulties. The visual difficulties were with visual smooth pursuit demonstrating saccadic eye movements, after the initial exam, chiropractic treatment of the cervical spine was initiated. After the treatment, the patient reported significant relief of his symptoms. After the seventh visit, the patient reported residual symptoms of a neck pain as well as blurred vision. He was referred to a performance vision optometrist for co-management, he was given visual exercises and reported on the eighth visit that he was symptom-free.
The second case was of another 19-year-old hockey player that was referred by his family physician to the chiropractor, following 2 years of post-concussion symptoms resulting from a body check. Symptoms included dizziness, tinnitus, headache, mental fogginess, sleep disturbance and mild visual difficulty’s particularly with reading and watching television. For the visual difficulties he was referred to a performance vison optometrist for co-management. This optometric care was not specified in the article. His care was still ongoing during the writing of the article by the authors (Marshall et al., 2015).
Discussion and Conclusion
This review on vision rehabilitation interventions following mild traumatic brain injury, contains 10 articles published between 2008 and 2017. The majority of the studies (86%) were published in the last 6 years, indicating that this topic is current and the number of researches done in this area is growing. In most of these studies, optometrists appeared to be conducting various interventions. Only two of them described, in minor detail, a co-management between the optometrist and the chiropractor.
Referring to my own clinical experience, there is some co-management between allied health professions, such as occupational therapists, physiotherapists, chiropractors, dieticians and optometrists but not on a broad scale. The current research doesn’t reflect this co-management options for visual intervention after mild traumatic brain injury. This may be due to the different terminology used by the various health professionals and needs further investigation. The mean age of participants in the current research is relatively young, this article didn’t include research where the mean age was around 65 years of age although this represents a significant number of TBI that occur each year (Nguyen et al., 2016).
Also, the study samples were small and consisted of mostly male patients, future research should contain a lager and more age and gender diverse population. Reviewing the findings of the articles used there are a number of promising and clinically significant interventions for vision rehabilitation after mild traumatic brain injury. The nature of these interventions varies from optical devices, vision therapy or chiropractic intervention in some cases. The main focus for future research should be on the more diverse and multi-professional collaboration across the different heath professionals, that is, providing better models for multidisciplinary intervention for visual deficits in traumatic brain injury patients.
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Caldwell, C., & Reyes-Cabrera, E. (2015). A Deliberate Set of Examinations and the Application of Yoked Prisms in the Treatment of Visual Midline Shift Syndrome: A Case Report. Optometry & Visual Performance, 3(6), 291-297.
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