Concussion, brain injuries, and other neurologic conditions carry a high incidence of visual symptoms and findings. A neuro optometric evaluation can diagnose visual difficulties that reduce quality of life and create a treatment plan for remediation. Improved visual function will result in better rehabilitation outcomes. This article highlights tools such as the Brain Injury Vision Symptom Survey, Vestibular and ocular motor screening, and one approach to prescribing microprism for patients with neurologic deficits. Small amounts of prism (microprism), along with other treatments, can be used to reduce symptoms in the patient with post-concussion syndrome. Neuro Optometric Rehabilitation and microprism should be considered for all patients with all patients that have suffered a concussion.
Key points
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Concussion, brain injuries, and other neurologic conditions carry a high incidence of visual symptoms and findings.
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The common visual sequalae of post-concussion syndrome (PCS) often includes convergence insufficiency, deficiencies of oculomotor function, accommodative deficits, as well as visual perceptual and visual vestibular and visual motor deficits.
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Small amounts of prism (microprism), along with other treatments, can be used to reduce symptoms in the patient with PCS
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Neuro Optometric Rehabilitation and microprism should be considered for all patients with all patients that have suffered concussion.
Introduction
A concussion is a mild subtype of Traumatic Brain Injury (mTBI) that affects brain function [ , ]. However, the term “mild” should not be equated with insignificant. Symptoms following mTBI vary greatly from patient to patient and the length of time an individual experiences these effects also varies greatly. Post Trauma Vision Syndrome (PTVS) presents as the most common visual sequelae of mTBI, encompassing a variety of signs and symptoms that may include convergence insufficiency (CI), accommodative dysfunction, minimum blink rate, reduced concentration or attention, oculomotor deficits, and visual-spatial distortion often associated with an abnormal egocentric localization [ ].
Because symptoms of PTVS occurring in patients with mTBI and symptoms of Post-Concussion Syndrome (PCS) are so similar, in this article we will use the terms mTBI and PCS interchangeably. Most patients also experience significant non-visual symptoms that linger in PCS, ranging from sleep disturbances and cervical strain to increased levels of anxiety and depression [ ]. Co-management with physical and occupational therapists, chiropractors, speech/language therapists, neurologists, and physiatrists, therefore, is indicated for many patients diagnosed with mTBI.
The prognosis for full visual recovery following a concussion is generally positive. Many treatment options exist, depending on the severity of symptoms, including lenses, prisms, and optometric vision therapy [ ]. As reviewed by Press [ ], the term microprism was originally introduced by Bowan to denote low amounts of therapeutic base-in prism typically in the range of 1 prism diopter but also can apply to other base orientations of the prism. Microprism has gained traction as a successful tool in optometric visual rehabilitation.
The approach detailed by Press makes use of conventional tools to probe indications for microprism, as one would do for convergence insufficiency and other forms of binocular dysfunction. These include associated phoria, fixation disparity, free space fusion, jump vergence, and stereopsis. While we make use of these tools for the binocular evaluation of patients with mTBI, we have found other means of clinical assessment valuable as well. These probes are addressed in the section that follows and are illustrated through a case series of 5 patients.
Clinical assessment
Our approach to therapeutic interventions for PCS begins with identifying symptomatic problems through the Brain Injury Vision Symptom Survey (BIVSS). The BIVSS is a 28-item symptom checklist that has shown 82.2% sensitivity in predicting TBI [ ]. The BIVSS, reproduced in Appendix 1 , shows very good test-retest reliability, enabling it to serve as a valuable tool for assessing and quantifying visual symptoms associated with mild to moderate TBI [ ]. The BIVSS lets patients share their symptoms based on frequency of occurrence rather than severity or intensity of symptoms. This allows much more accurate tracking of symptoms over time, as patients may adjust their perceived pain levels as healing begins to occur. The BIVSS has become an essential component in documenting the patient’s case history, adding confirmation to the visual elements of PCS.
In addition to static tests behind the phoropter, the clinical tests that we commonly employ for this population are dynamic and tap heavily into the vestibular and ocular motor systems [ , ]. In particular, we use a modified version of the Visual/Ocular Motor Screening (VOMS). VOMS testing, detailed in Appendix 2 , includes smooth pursuits, saccades, near point of convergence (NPC), vestibulo-ocular reflex (VOR) testing, and visual motion sensitivity testing (Figures not included). Our symptomatic PCS patients typically report subjective discomfort that is exacerbated during VOMS testing. Objectively, when measuring patients with PCS, one often notes a receded endpoint for the NPC, increased “jerky” appearance or head movement in their pursuits and saccades, and visible discomfort while performing the VOR testing. In addition, we conduct a standard optometric binocular vision evaluation including tests of ocular health, visual field, egocentric localization, sensory and motor fusion, accommodation, and vergence ranges.
Headaches are a common complaint in mTBI, but can potentially be a sign of neurologic insult within the visual pathways. We therefore routinely conduct automated perimetry with the Octopus 30-2 visual field test. Visual field abnormalities are common following mTBI and can vary from small scotomas, generalized constriction, homonymous hemifield loss, or in extreme cases total visual field loss [ ]. ( Fig. 1 ) Abnormalities that are due to visual hypersensitivity following a concussion will be transient and often resolve if the test is repeated; those that are due to structural damage will not.
The visual evoked potential (VEP) test is not routinely used in clinical practice but can be utilized to assess the patient with PCS. That is because it is a measure of the amount of information (amplitude) and transmission time (latency) from the eyes through the optic nerves to the occipital lobe. No other objective test exists that provides this information. Pattern visually evoked potentials (VEPs) were run as a baseline and again to determine response to treatment lenses. Patients with PTVS show decreased VEP amplitude and latency, often normalizing with the application of binasal occlusion and low amounts of base in prism [ , ].
Once the clinical profile of a patient with PTVS is established utilizing a neuro-optometric rehabilitation assessment that includes the BIVSS, VOMS, binocular assessment, and the VEP, the data are factored together with the refraction to formulate a tentative spectacle lens Rx. As noted by Press, the binocular profile often points to improved convergence, improved stereopsis, more balanced ranges, more stable associated phoria or fixation disparity, improved stereopsis, and a greater sense of comfort or clarity when conventional binocular probes are repeated through microprism in the horizontal and/or vertical direction [ ]. We have found analogous changes when our probes utilizing the BIVSS, VOMS, and VEP are repeated through the tentative microprism derived through the binocular assessment, typically 0.5ˆ or 1.0ˆ micro prism base-in or base-down.
Based on improvement in scores on the BIVSS and VOMS, and improvement in VEP latency or amplitude, microprism is incorporated into the Rx. Although many patients accept the same microprism at distance and near, if trial framing indicates different values at distance and near, we dispense 2 separate Rxs as appropriate. When the patient’s BIVSS indicates photophobia or light sensitivity as a significant symptom, we present the option of adding tinting to the prescription as well. This includes FL41, Blutech, Avulux, 10% blue, or polarized sunglass tints to complement a rehabilitation program. Although vision therapy remains an important approach for patients with mTBI, we found that lenses and prisms in some cases can result in instantaneous symptom reduction, are cost-effective, and require minimal time or patient effort.
Case series results
The 5 representative patients assessed ranged from 17 to 60 year old. One patient suffered from a fall resulting in a head injury, 1 patient had a sports-related head injury, and 3 patients were injured in motor vehicle accidents.
Table 1 shows the initial BIVSS scores. As noted previously, the BIVSS is a 28-item questionnaire. It has a Likert scale of 0 to 4, and, if the maximum score of 4 is recorded for each question, the total is 112. The scoring is based on how frequently a patient will experience symptoms, with a 0 correlating to “never” and a 4 correlating to “always.” Patients diagnosed with brain injury typically have a score greater than 32; the BIVSS scores for our patients ranged from 39 to 60. The middle column of Table 1 indicates the primary symptoms that patients were hoping to address through treatment.
| Patient | Age | BIVSS | Main symptoms | VOR/Visual motion rating |
|---|---|---|---|---|
| AG | 60 | 44/112 | Reading issues, HA, motion sickness | H 4/10, V 4/10, C 4/10 |
| LC | 53 | 60/112 | Dizziness, HA, reading issues | H 5/10, V 5/10, C 6/10 |
| LB | 17 | 54/112 | HA, reading issues | H 0/10, V 0/10, C 5/10 |
| BA | 27 | 44/112 | Light sensitivity, HA | H 6/10, V 6/10, C 7/10 |
| AG | 29 | 39/112 | Light sensitivity, HA, dizziness | H 0/10, V 4/10, C 5/10 |
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