Concussion Vision Treatment – Overview
Concussion vision treatment are commonly provided by Neuro-optometrists, OTs and PTs. Notwithstanding problems with the research (outlined below), there is emerging evidence that vision therapy is effective at accelerating & enhancing the natural neuroplastic recovery process. If patients had no limitations in their energy, time, &/or finances, they could consult each profession. Failing this, the professions need to work collaboratively and strategically to deliver these much-needed vision treatments.
Concussion Vision Treatment – More in-depth
This second part of Bits and Bytes on concussion vision treatment will look at the evidence, the dosages needed, and who should be providing these treatments.
Concussion Vision Therapy – Evidence
Three review studies have been very helpful in looking at the evidence for vision rehabilitation used for concussions (mTBI). In the earliest of the three, Hunt et al. looked at the assessment of visual dysfunction. They found preliminary evidence that clinical measurements of saccades, smooth pursuit and vergence were useful in detecting change in cases of mTBI.1 Berger et al. in their systematic review of occupational therapist’s vision treatment found variability in effectiveness of treatments based on which interventions were employed. 2
The most recent study, Simpson & Hunt built on the work of the two previous reviews. Their focus was on research investigating the efficacy of vision therapy specifically for mTBIs. Simpson et al.’s review focused only on interventional research aimed at basic visual skills (i.e. oculomotor control and acuity).3 Using an established “scoping review” protocol, they winnowed down over 2,500 articles to just 22 studies. Simplifying the authors’ categorization, these included: 6 crossover studies (5 using the same participants), 6 case studies, 5 retrospective chart reviews, 3 group experimental designs, 1 prospective observational trial and 1 randomized, double blind, sham controlled study. Ninety five percent of the studies reported at least one improvement in basic vision skills and associated reductions in visually related symptoms. Only one study, related to the use of hypobaric oxygen to improve basic vision skills, found no improvement. A number of limitations were identified by the authors: 77% of the studies had 40 or fewer participants, symptom duration varied from 1 week to 30 years, none of the studies employed multidisciplinary interventions, and children, youth (under 18), & older individuals were poorly represented.
While surveys of literature like this are very useful for clinicians, they do have limitations intrinsic to their nature. The studies reviewed were quite heterogeneous, both in design and quality. A meta-analysis would be helpful, but given the limited number and quality of studies this is not yet possible. It is necessary therefore to mine deeper down to the individual study level. 5 studies by Thiagarajan et al. are worthy of further discussion.4-8 The first 4 articles all used the same crossover & sham design (single blind) and 12 participants. To avoid normal time-dependent recovery, all participants had had their visual disability for at least 1 year. Only lab-based oculomotor training (OMT) was employed. This OMT comprised 45 min sessions, 2 times /week, over 6 weeks (total 9 hrs). The 5th study investigated how gains made by the above participants persisted following treatment.8 The authors reported a great majority of the basic vision skills were improved. These included: reading speed, saccadic movement accuracy, rhythmicity, convergence/divergence speed, accommodation capacity and decreased fixation errors. In addition, reading comfort and subjective visual attention were significantly enhanced. By the end of the training regime, some of the 13 parameters returned to normal, other were improved to a significant level, and some showed only a trend towards improvement. During the cross over sham training period, no improvements occurred in any of these parameters.
In the 5th study, 8 of the 12 individuals were retested at the 3 and 6 month point following training. No OMT was done between these follow-up periods. Thiagarajan et al. reported that 8 of the 13 parameters were either maintained or continued to improve upon retesting. The authors hypothesized with a doubling of the training period, more parameters would be returned to normal or to a significant level.8 Notwithstanding the valid criticisms regarding number of participants, etc., these 5 studies constitute more than just preliminary evidence for the effectiveness of vision therapy. In my opinion, clinicians working with these patients can now have more confidence that vision therapy works. Further research is needed to raise this confidence level. In my view, given the conservative, low-risk nature of these therapies, it is not practical to wait until all the evidence is ironclad before trying to help patients with vision therapy.
Concussion Vision Treatment – Dosage
The dosage of treatments reported varied widely in the 22 studies reviewed by Simpson & Hunt. When defined, in-lab treatments (training a wide variety of skills) varied from 36 min to 45 min / session. The number of sessions varied from 6 to 16 sessions. Duration of treatments lasted from 2 weeks to 8 months. Only one study reported a protocol of 15 min /day, 5 days a week of home exercises. A number of other studies reported home exercise, but did not specify the dosage.3
As always the questions of when, where and frequency of rehab treatments requires much more research. This seems especially important in the case of vision therapy, as appointments are expensive, are not covered by public health systems, and are rarely covered by the patient’s extended health insurance. It is known that neuroplastic change (needed in the recovery all ABIs) takes time. The goal of treatment therefore should be to accelerate and improve this natural neuroplastic recovery. Given the large number of domains an mTBI patient often needs to work on, it is unclear what justification there is for a vision therapist seeing patients frequently in a given week. Treatment effectiveness in all treatment domains can be greatly improved (& patient’s cost/energy output reduced) by augmenting in-clinic programs with well-designed, evidence-based home exercises.
Concussion Vision Treatment – Who should be providing it?
Having a neuro-optometrist on a concussed patient’s team is invaluable, arguably often indispensable. Neuro-optometrists possess the educational base and specialized knowledge of vision assessments from structural, pathological and functional issues. They have the expertise to customize OMT to the individual’s needs and the ability to prescribe, if needed, assistive equipment (e.g. yoked prisms). This goes well beyond the “pencil pushups” exercises routinely given (without adequate consideration to need or timing) by some rehab clinicians. Optimally the three professions, Neuro-optometrists, OTs and PTs, should all be working at what they do best. However the reality is, without insurance coverage, many patients go without key components that each profession can best provide. In addition, fatigue is an almost universal symptom of concussions and PCS. Energy, like finance, is therefore a very finite resource for many of these patients, one that needs to be carefully managed by all parties.
The answer to this is strong multidisciplinary & strategic collaborations. PTs and OTs working in this sphere need to better understand the components of vision therapy, recognize the limits of their knowledge and scope of practice. They & other therapists involved in care need to appreciate the knowledge and skills that Neuro-optometrists bring to the table. Likewise, Neuro-optometrists need to better understand what the other professions add, & the energy/time/money it takes patients to do these other therapies (e.g. cardiorespiratory, vestibular, MSK, pacing & planning, cognitive, emotional, & dietary/metabolic). All the clinicians need to be more cognizant of each patient’s unique needs & limitations (financial, etc.), and be willing to work with & collaborate with other professions. They all need to be more creative in prescribing exercises, both in the form of home exercises, as well as within other clinician’s programs.
- Hunt A. et al. Oculomotor-based vision assessment in mild traumatic brain Injury: a systematic review. Journal of Head Trauma Rehabilitation, 2016 31 (4): 252-261.
- Berger S. et al. Effectiveness of intervention to address visual and visual-perceptual impairments to improve occupational performance in adults with traumatic brain injury: a systematic review. American Journal of Occupational Therapy, 2016 70:1-7.
- Simpson M. & Hunt A. Vision rehabilitation interventions following mild traumatic brain injury: a scoping review. Disability and Rehabilitation, 2018.
- Thiagarajan P. et al. Oculomotor neurorehabilitation for reading in mild traumatic brain injury (mTBI): an integrative approach. Neurorehabilitation, 2014 34: 129-146.
- Thiagarajan P. & Ciuffreda K. Effect of oculomotor rehabilitation on vergence responsivity in mild traumatic brain injury. Journal of Rehabilitation Research and Development, 2013 50: 1223-1239.
- Thiagarajan P. & Ciuffreda K. Effects of oculomotor rehabilitation on accommodative responsivity in mild traumatic brain injury. Journal of Rehabilitation Research and Development, 2014 51: 175-191.
- Thiagarajan P. & Ciuffreda K. Versional eye tracking in mild traumatic brain injury (mTBI). Brain Injury, 2014 28: 930-943.
- Thiagarajan P. & Ciuffreda K. Short-term persistence of oculomotor rehabilitative changes in mild traumatic brain injury. Brain Injury, 2015 29: 1475-1479