Concurrent vision dysfunctions in convergence insufficiency with traumatic brain injury

OculoMotor & Vestibular Endurance Screening (MoVES) Normative, Repeatability, and Reliability Data

This study aims to assess oculomotor and vestibular endurance by utilizing the Oculomotor and Vestibular Endurance Screening (MoVES) assessment in athletes' pre-season and post-season and after a suspected head injury to detect impairment. Athletes (N = 311, 19.4 ± 1.3 years) were recruited to perform the following seven tasks: (1) horizontal saccades, (2) vertical saccades, (3) vergence jumps, (4) horizontal vestibular-oculomotor reflex (VOR), (5) vertical VOR, (6) amplitude of accommodation (AoA), and (7) near point of convergence (NPC). At pre-season, the observed number of eye movements in 60 s are horizontal saccades (74 ± 13 initial 30 s; 67 ± 11 latter 30 s), vertical saccades (70 ± 13; 66 ± 10), vergence jumps (48 ± 12; 45 ± 13), horizontal VOR (38 ± 11; 38 ± 11), and vertical VOR (8 ± 11; 38 ± 11). These results establish a normative database for eye movements within the MoVES assessment and show consistency in the number of movements from pre-season to post-season. The initial results show a trending decrease in the number of eye movements in the initial days post-head injury, which improves to pre-season measures 14-21 days post-injury. This foundation can be used by future studies to explore the extent of binocular and vestibular endurance dysfunctions caused by head injuries that subside within two weeks.

Convergence insufficiency in patients with post-concussion syndrome is accompanied by a higher symptom load: a cross-sectional study

OBJECTIVE

To estimate the prevalence of convergence insufficiency (CI) in adult patients with post-concussion syndrome and determine the impact of CI on symptom load.

METHODS

Cross-sectional study of 103 patients with neurological symptoms 2-6 months after a concussion. Symptoms were assessed with the Rivermead Post Concussion Symptoms Questionnaire (RPQ), and CI was diagnosed using near point of convergence, vergence facility, and the Convergence Insufficiency Symptom Survey. The RPQ score for patients with and without CI was compared, and sensitivity, specificity, and area under the receiver operating characteristic curve for the two visually related RPQ questions as indicators of CI were calculated.

RESULTS

The proportion of patients diagnosed with symptomatic CI was 20.4% (95% confidence interval: 13.1-29.5%). The RPQ score was significantly higher for patients with symptomatic CI both before (p = .01) and after removal of the two visually related questions in the RPQ-questionnaire (p = .03). The two visually related RPQ questions were unable to detect CI.

CONCLUSION

In patients with post-concussion syndrome, the load of nonvisual symptoms is higher in the presence of CI. A prospective interventional study on CI is required to study the relationship between CI and other post-concussion symptoms.

Vergence and accommodation deficits in paediatric and adolescent patients during sub-acute and chronic phases of concussion recovery

INTRODUCTION

Visual function deficits have been reported in adolescents following concussion. We compared vergence and accommodation deficits in paediatric and adolescent patients at a tertiary medical centre in the sub-acute (15 days to 12 weeks) and chronic (12 weeks to 1 year) phases of concussion recovery.

METHODS

The study included patients aged 7 to <18 years seen between 2014 and 2021, who had a binocular vision (BV) examination conducted within 15 days and 1 year of their concussion injury. Included patients had to have 0.10 logMAR monocular best-corrected vision or better in both eyes and be wearing a habitual refractive correction. BV examinations at near included measurements of near point of convergence, convergence and divergence amplitudes, vergence facility, monocular accommodative amplitude and monocular accommodative facility. Vergence and accommodation deficits were diagnosed using established clinical criteria. Group differences were assessed using nonparametric statistics and ANCOVA modelling.

RESULTS

A total of 259 patients were included with 111 in the sub-acute phase and 148 in the chronic phase of concussion recovery. There was no significant difference in the rates of vergence deficits between the two phases of concussion recovery (sub-acute = 48.6%; chronic = 49.3%). There was also no significant difference in the rates of accommodation deficits between the two phases of concussion recovery (sub-acute = 82.0%; chronic = 77.0%).

CONCLUSION

Patients in both the sub-acute and chronic phases of concussion recovery exhibited a high frequency of vergence and accommodation deficits, with no significant differences between groups. Results indicate that patients exhibiting vision deficits in the sub-acute phase may not resolve without intervention, though a prospective, longitudinal study is required to test the hypothesis.

Diagnostic values of questionnaires of Convergence Insufficiency Symptom Survey and College of Optometrists Vision Development Quality of Life in the screening of convergence insufficiency

AIM

To compare and analyse the diagnostic efficacy of the College of Optometrists Vision Development Quality of Life Questionnaire (COVD-QOL) and the Convergence Insufficiency Symptom Survey (CISS) in detecting convergence insufficiency and to compare their diagnostic value in clinical applications.

METHODS

Using the diagnostic test method, 62 adult patients with convergence insufficiency (age: 24.74±3.75y) and 62 normal participants (age: 23.61±3.13y) who visited the Optometry Clinic of West China Hospital of Sichuan University from April 2021 to January 2023 were included. All subjects completed the CISS and COVD-QOL. Statistical analysis of the sensitivity and specificity of the CISS and COVD-QOL and comparison and joint experimental analysis of their diagnostic efficacy were performed.

RESULTS

The sensitivity of the CISS and COVD-QOL for convergence insufficiency was 64.5% and 71.0%, respectively, while the specificity was 96.8% and 67.7%, respectively. Compared to the CISS alone, the combination of the CISS and COVD-QOL demonstrated lower sensitivity and specificity. The areas under the receiver operating characteristic curve of CISS, COVD-QOL and CISS combined with COVD-QOL were 0.806, 0.694 and 0.782, respectively.

CONCLUSION

Considering the low sensitivity of the CISS and the low specificity of the COVD-QOL, it is recommended to supplement these questionnaires with other screening tests for the detection of convergence insufficiency.

Blue Light-Ocular and Systemic Damaging Effects: A Narrative Review

Light is a fundamental aspect of our lives, being involved in the regulation of numerous processes in our body. While blue light has always existed in nature, with the ever-growing number of electronic devices that make use of short wavelength (blue) light, the human retina has seen increased exposure to it. Because it is at the high-energy end of the visible spectrum, many authors have investigated the theoretical harmful effects that it poses to the human retina and, more recently, the human body, given the discovery and characterization of the intrinsically photosensitive retinal ganglion cells. Many approaches have been explored, with the focus shifting throughout the years from examining classic ophthalmological parameters, such as visual acuity, and contrast sensitivity to more complex ones seen on electrophysiological assays and optical coherence tomographies. The current study aims to gather the most recent relevant data, reveal encountered pitfalls, and suggest future directions for studies regarding local and/or systemic effects of blue light retinal exposures.

Quotidian Profile of Vergence Angle in Ambulatory Subjects Monitored With Wearable Eye Tracking Glasses

Purpose

Wearable eye trackers record gaze position as ambulatory subjects navigate their environment. Tobii Pro Glasses 3 were tested to assess their accuracy and precision in the measurement of vergence angle.

Methods

Four subjects wore the eye tracking glasses, with their head stabilized, while fixating at a series of distances corresponding to vergence demands of: 0.25, 0.50, 1, 2, 4, 8, 16, and 32°. After these laboratory trials were completed, 10 subjects wore the glasses for a prolonged period while carrying out their customary daily pursuits. A vergence profile was compiled for each subject and compared with interpupillary distance.

Results

In the laboratory, the eye tracking glasses were comparable in accuracy to remote video eye trackers, outputting a mean vergence value within 1° of demand at all angles except 32°. In ambulatory subjects, the glasses were less accurate, due to tracking interruptions and measurement errors, partly mitigated by the application of data filters. Nonetheless, a useful record of vergence behavior was obtained in every subject. Vergence profiles often had a bimodal distribution, reflecting a preponderance of activities at near (mobile phone and computer) or far (driving and walking). As expected, vergence angle correlated with interpupillary distance.

Conclusions

Wearable eye tracking glasses make it possible to compile a nearly continuous record of vergence angle over hours, which can be correlated with the corresponding visual scene viewed by ambulatory subjects.

Translational Relevance

This technology provides new insight into the diversity of human ocular motor behavior and may become useful for the diagnosis of disorders that affect vergence function such as: convergence insufficiency, Parkinson disease, and strabismus.

Vision and Concussion: Symptoms, Signs, Evaluation, and Treatment

Visual symptoms are common after concussion in children and adolescents, making it essential for clinicians to understand how to screen, identify, and initiate clinical management of visual symptoms in pediatric patients after this common childhood injury. Although most children and adolescents with visual symptoms after concussion will recover on their own by 4 weeks, for a subset who do not have spontaneous recovery, referral to a specialist with experience in comprehensive concussion management (eg, sports medicine, neurology, neuropsychology, physiatry, ophthalmology, otorhinolaryngology) for additional assessment and treatment may be necessary. A vision-specific history and a thorough visual system examination are warranted, including an assessment of visual acuity, ocular alignment in all positions of gaze, smooth pursuit (visual tracking of a moving object), saccades (visual fixation shifting between stationary targets), vestibulo-ocular reflex (maintaining image focus during movement), near point of convergence (focusing with both eyes at near and accommodation (focusing with one eye at near because any of these functions may be disturbed after concussion. These deficits may contribute to difficulty with returning to both play and the learning setting at school, making the identification of these problems early after injury important for the clinician to provide relevant learning accommodations, such as larger font, preprinted notes, and temporary use of audio books. Early identification and appropriate management of visual symptoms, such as convergence insufficiency or accommodative insufficiency, may mitigate the negative effects of concussion on children and adolescents and their quality of life.

Rapid Automatized Picture Naming in an Outpatient Concussion Center: Quantitative Eye Movements during the Mobile Universal Lexicon Evaluation System (MULES) Test

Number and picture rapid automatized naming (RAN) tests are useful sideline diagnostic tools. The main outcome measure of these RAN tests is the completion time, which is prolonged with a concussion, yet yields no information about eye movement behavior. We investigated eye movements during a digitized Mobile Universal Lexicon Evaluation System (MULES) test of rapid picture naming. A total of 23 participants with a history of concussion and 50 control participants performed MULES testing with simultaneous eye tracking. The test times were longer in participants with a concussion (32.4 s [95% CI 30.4, 35.8] vs. 26.9 s [95% CI 25.9, 28.0], t=6.1). The participants with a concussion made more saccades per picture than the controls (3.6 [95% CI 3.3, 4.1] vs. 2.7 [95% CI 2.5, 3.0]), and this increase was correlated with longer MULES times (r = 0.46, p = 0.026). The inter-saccadic intervals (ISI) did not differ between the groups, nor did they correlate with the test times. Following a concussion, eye movement behavior differs during number versus picture RAN performance. Prior studies have shown that ISI prolongation is the key finding for a number-based RAN test, whereas this study shows a primary finding of an increased saccade number per picture with a picture-based RAN test. Number-based and picture-based RAN tests may be complimentary in concussion detection, as they may detect different injury effects or compensatory strategies.

Montreal Brain Injury Vision Screening Test for General Practitioners

Visual disturbances are amongst the most commonly reported symptoms after a traumatic brain injury (TBI) despite vision testing being uncommon at initial clinical evaluation. TBI patients consistently present a wide range of visual complaints, including photophobia, double vision, blurred vision, and loss of vision which can detrimentally affect reading abilities, postural balance, and mobility. In most cases, especially in rural areas, visual disturbances of TBI would have to be diagnosed and assessed by primary care physicians, who lack the specialized training of optometry. Given that TBI patients have a restricted set of visual concerns, an opportunity exists to develop a screening protocol for specialized evaluation by optometrists—one that a primary care physician could comfortably carry out and do so in a short time. Here, we designed a quick screening protocol that assesses the presence of core visual symptoms present post-TBI. The MOBIVIS (Montreal Brain Injury Vision Screening) protocol takes on average 5 min to perform and is composed of only “high-yield” tests that could be performed in the context of a primary care practice and questions most likely to reveal symptoms needing further vision care management. The composition of our proposed protocol and questionnaire are explained and discussed in light of existing protocols. Its potential impact and ability to shape a better collaboration and an integrative approach in the management of mild TBI (mTBI) patients is also discussed.

Mild-to-Moderate Traumatic Brain Injury: A Review with Focus on the Visual System

Traumatic Brain Injury (TBI) is a major global public health problem. Neurological damage from TBI may be mild, moderate, or severe and occurs both immediately at the time of impact (primary injury) and continues to evolve afterwards (secondary injury). In mild (m)TBI, common symptoms are headaches, dizziness and fatigue. Visual impairment is especially prevalent. Insomnia, attentional deficits and memory problems often occur. Neuroimaging methods for the management of TBI include computed tomography and magnetic resonance imaging. The location and the extent of injuries determine the motor and/or sensory deficits that result. Parietal lobe damage can lead to deficits in sensorimotor function, memory, and attention span. The processing of visual information may be disrupted, with consequences such as poor hand-eye coordination and balance. TBI may cause lesions in the occipital or parietal lobe that leave the TBI patient with incomplete homonymous hemianopia. Overall, TBI can interfere with everyday life by compromising the ability to work, sleep, drive, read, communicate and perform numerous activities previously taken for granted. Treatment and rehabilitation options available to TBI sufferers are inadequate and there is a pressing need for new ways to help these patients to optimize their functioning and maintain productivity and participation in life activities, family and community.

Vestibulo-ocular dysfunction in mTBI: Utility of the VOMS for evaluation and management – A review

BACKGROUND: Individuals who have suffered a concussion/mild traumatic brain injury (mTBI) frequently report symptoms associated with vestibular and/or oculomotor dysfunction (VOD) like dizziness, nausea, fatigue, brain fog, headache, gait and neurocognitive impairments which are associated with the development of chronic symptoms. The Vestibular/Ocular Motor Screening (VOMS) tool has been established as a reliable and clinically relevant complement to use alongside a battery of post-concussion tests to improve screening and referral for further evaluation and treatment of VOD. OBJECTIVES: This paper will review the pathoanatomy and symptomatology of common vestibular and oculomotor disorders after concussion, as well as the utility of the VOMS to assist in diagnosis, referral, and management. METHODS: Primary articles were identified using a search via PubMed, Google Scholar, OneSearch, and CINAHL. Search key terms were combinations of “mild traumatic brain injury” or “concussion” or “pursuit” or “accommodation” or “vergence” or “convergence insufficiency” or “saccades” or “vestibulo-ocular reflex” or “vestibular ocular motor screen” or “vestibular rehabilitation”, or “vision rehabilitation” including adult and pediatric populations that were published in print or electronically from 1989 to 2021 in English. Classic papers on anatomy of eye movements, vestibular system and pathological changes in mTBI were also included, regardless of publication date. RESULTS: Objective impairments are commonly found during testing of smooth pursuit, saccades, vergence, accommodation, vestibular ocular reflex, and visual motion sensitivity after mTBI. These deficits can be actively treated with vestibular physical therapy and oculomotor/neuro-optometric vision therapy. VOMS is an efficient and reliable tool that can be used by all healthcare and rehabilitation providers to aid in diagnosis of post-concussion VOD, to help facilitate the decision to refer for further evaluation and treatment to expedite symptomatic post-concussion recovery. CONCLUSIONS: VOD is common after concussion in acute, post-acute, and chronic phases. Once areas of impairments are identified through proper assessment, clinicians can maximize recovery by referring to vestibular physical therapy and/or neuro-optometry to design a targeted treatment program to address individual deficits.

Neuro-Visual and Vestibular Manifestations of Concussion and Mild TBI

PURPOSE OF REVIEW

Mild traumatic brain injury, or concussion, is a major cause of disability. Vestibular and visual dysfunction following concussion is common and can negatively affect patients' well-being and prolong recovery. Etiologies of visual and vestibular symptoms are numerous, including ocular, neuro-ophthalmic, otologic, and neuro-vestibular conditions. Some etiologies are benign and may be treatable, while others are potentially vision or life-threatening, making a focused history and examination essential. This review offers an approach to the evaluation and treatment of the most common neuro-visual and vestibular impairments that may result from concussion.

RECENT FINDINGS

Treatment of concussion including exercise, computerized programs, transcranial magnetic stimulation, gene therapy, stem cell therapy, and nanoparticles has shown promise. Many novel therapies are in the pipework for visual and vestibular recovery after concussion; however, the treatment mainstay remains therapy and evaluation for co-existing diseases.

Clinical testing of mild traumatic brain injury using computerised eye-tracking tests

Traumatic brain injury (TBI) refers to the alteration of typical brain function that occurs following a blow to the head. Even a mild case of traumatic brain injury (mTBI) can lead to long-term impairment, so accurate and timely detection is vital. Visual symptoms are common following mTBI, so while it may seem to fall outside their typical scope of practice, optometrists are ideally qualified to assess the visual impacts and help with the diagnosis of mTBI. Given that mTBI is challenging to objectively diagnose and has no universally accepted diagnostic criteria, clinicians can lack confidence in diagnosing mTBI, and be hesitant in becoming involved in the management of such patients. The development of easily quantifiable techniques using eye tracking as an objective diagnostic tool provides practitioners with an easier pathway into the field, assigning numerical values to parameters which are difficult to assess using conventional optometric tests. As this evolving technology becomes increasingly integrated into optometric clinical settings, the potential for it to identify deficits accurately and reliably in patients following mTBI, and to monitor both their recovery and the effectiveness of potential treatments will increase. This paper provides an overview of clinical tests, relevant to optometrists, that can uncover oculomotor, attentional, and exteroceptive deficits following a mTBI, so that an optometrist with an interest in eye tracking can play a role in the detection and monitoring of mTBI symptoms.

Peering into the Brain through the Retrosplenial Cortex to Assess Cognitive Function of the Injured Brain

The retrosplenial cortex (RSC) is a posterior cortical area that has been drawing increasing interest in recent years, with a growing number of studies studying its contribution to cognitive and sensory functions. From an anatomical perspective, it has been established that the RSC is extensively and often reciprocally connected with the hippocampus, neocortex, and many midbrain regions. Functionally, the RSC is an important hub of the default-mode network. This endowment, with vast anatomical and functional connections, positions the RSC to play an important role in episodic memory, spatial and contextual learning, sensory-cognitive activities, and multi-modal sensory information processing and integration. Additionally, RSC dysfunction has been reported in cases of cognitive decline, particularly in Alzheimer's disease and stroke. We review the literature to examine whether the RSC can act as a cortical marker of persistent cognitive dysfunction after traumatic brain injury (TBI). Because the RSC is easily accessible at the brain's surface using in vivo techniques, we argue that studying RSC network activity post-TBI can shed light into the mechanisms of less-accessible brain regions, such as the hippocampus. There is a fundamental gap in the TBI field about the microscale alterations occurring post-trauma, and by studying the RSC's neuronal activity at the cellular level we will be able to design better therapeutic tools. Understanding how neuronal activity and interactions produce normal and abnormal activity in the injured brain is crucial to understanding cognitive dysfunction. By using this approach, we expect to gain valuable insights to better understand brain disorders like TBI.

The development and the inter-rater agreement of a treatment protocol for vestibular/oculomotor rehabilitation in children and adolescents post-moderate-severe TBI

Introduction:There is limited evidence investigating the effect of vestibular/oculomotor rehabilitation programs in children and adolescents post moderate-severe TBI at the sub-acute stage.Objective:To describe the development of a treatment protocol for vestibular/oculomotor interventions in this population, and to assess the inter-rater agreement of this protocol as an initial step of a clinical trial.Method:The protocol was developed by 10 health professionals, address the high variability of balance performance, the high prevalence of vestibular/oculomotor abnormalities and the low prevalence of symptoms reported in this population.Results:The protocol enables the clinician to use the assessment during the treatment exercise selection. The training position was defined by the Pediatric Balance Scale. Vestibular/oculomotor exercises were selected using a quantified version of the Vestibular/Ocular Motor Screening. The exercise protocol was selected based on impairment in function or reproduction of symptoms. The protocol planning was implemented by two assessors in 27 children and adolescents post-moderate-severe TBI (median age 14.1 [6-18.4] years) in the sub-acute stage (median 40 [14-162] days since injury). Very high agreement was found (k > 0.72) in all the parameters.Conclusion: This protocol could reliably be used in a randomized control trial that assesses the effect of vestibular/oculomotor rehabilitation program in children and adolescents post moderate-severe TBI at the sub-acute stage.

Afferent Visual Manifestations of Traumatic Brain Injury

Traumatic brain injury (TBI) causes structural and functional damage to the central nervous system including the visual pathway. Defects in the afferent visual pathways affect visual function and in severe cases cause complete visual loss. Visual dysfunction is detectable by structural and functional ophthalmic examinations that are routine in the eye clinic, including examination of the pupillary light reflex and optical coherence tomography (OCT). Assessment of pupillary light reflex is a non-invasive assessment combining afferent and efferent visual function. While a assessment using a flashlight is relatively insensitive, automated pupillometry has 95% specificity and 78.1% sensitivity in detecting TBI-related visual and cerebral dysfunction with an area under the curve of 0.69-0.78. OCT may also serve as a noninvasive biomarker of TBI severity, demonstrating changes in the retinal ganglion cell layer and nerve fiber layer throughout the range of TBI severity even in the absence of visual symptoms. This review discusses the impact of TBI on visual structure and function.

Photophobia Associated with Traumatic Brain Injury: A Systematic Review and Meta-analysis

SIGNIFICANCE

This study reports the prevalence and relative risk of photophobia in patients with traumatic brain injury (TBI).

OBJECTIVES

This study aimed to conduct a systematic review and meta-analysis to determine the prevalence and relative risk of photophobia in patients with TBI.

DATA SOURCES

Three databases were used for literature search: PubMed, EMBASE, and Cochrane Library.

STUDY APPRAISAL AND SYNTHESIS METHODS

Publications reporting the prevalence of photophobia after TBI in patients of any age were included. A series of meta-regression analyses based on a generalized linear mixed model was performed to identify potential sources of heterogeneity in the prevalence estimates.

RESULTS

Seventy-five eligible publications were identified. The prevalence of photophobia was 30.46% (95% confidence interval [CI], 20.05 to 40.88%) at 1 week after the injury. Prevalence decreased to 19.34% (95% CI, 10.40 to 28.27%) between 1 week and 1 month after TBI and to 13.51% (95% CI, 5.77 to 21.24%) between 1 and 3 months after the injury. The rapid decrease in the prevalence of photophobia in the first 3 months after a TBI injury was significant (P < .001). Three months post-TBI, the prevalence of photophobia leveled off to a near plateau with nonsignificant variability, increasing between 3 and 6 months (17.68%; 95% CI, 9.05 to 26.32%) and decreasing between 6 and 12 months since TBI (14.85%; 95% CI, 6.80 to 22.90%). Subgroup analysis of 14 publications that contained control data showed that the estimated risk ratio for photophobia was significantly higher in the TBI than in the control group during the entire 12 months after TBI.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

This study demonstrates that photophobia is a frequent complaint after TBI, which largely resolves for many individuals within 3 months after the injury. For some patients, however, photophobia can last up to 12 months and possibly longer. Developing an objective quantitative methodology for measuring photophobia, validating a dedicated photophobia questionnaire, and having a specific photophobia International Classification of Diseases, Tenth Revision code would greatly improve data gathering and analysis.

OculoMotor Assessment Tool Test Procedure and Normative Data

SIGNIFICANCE

This study establishes normative data and a testing procedure for the oculomotor assessment tool. The oculomotor assessment tool standardizes visual targets for the Vestibular/OculoMotor Screening assessment and provides additional metrics that may aid in the differentiation between those with normal and those with abnormal oculomotor function potentially caused by a concussion.

PURPOSE

This study aimed to assess the oculomotor endurance of healthy participants with no self-reported history of concussions using the oculomotor assessment tool.

METHODS

Healthy participants (n = 376, average age of 20.4 years, range of 11 to 34 years, with no self-reported history of concussions) were recruited to perform the following three tasks for 60 seconds each: (1) horizontal saccades, (2) vertical saccades, and (3) vergence jumps. The participants were instructed to alternate visual fixation between two targets for each of the tasks as fast as they could without overshooting or undershooting the visual target. The differences in the number of eye movements between the initial and latter 30 seconds of the 1-minute test were analyzed.

RESULTS

A statistical difference (P < .001) was observed in the number of eye movements for all three tasks (horizontal saccades [70 ± 15 for initial 30 seconds, 63 ± 13 for latter 30 seconds], vertical saccades [68 ± 14, 63 ± 13], and vergence jumps [43 ± 11, 39 ± 10]) between the initial and latter 30 seconds. No significant differences were identified in the number of eye movements or the change in eye movements between the initial and latter 30 seconds based on sex.

CONCLUSIONS

These results establish a normative database for various eye movements. These data could potentially be used to compare different patient populations who have binocular endurance dysfunctions potentially due to traumatic brain injury, such as patients with concussion(s).

Effects of CranioSacral therapy upon symptoms of post-acute concussion and Post-Concussion Syndrome: A pilot study

OBJECTIVE

The purpose of this study was to investigate the utilization of CranioSacral Therapy (CST) in patients with Post-Concussion Syndrome (PCS) and capture patient-reported perceptions of clinical outcomes of lived treatment experiences.

DESIGN

Two-part, longitudinal study conducted through a chart review of target group, followed by a Patient-reported Treatment Outcome Survey (PTOS).

PARTICIPANTS

A convenience sample of 212 patients with a historical incidence of head trauma not requiring hospitalization was obtained through medical records department dating back ten years. Inclusion criteria for further chart review (n = 67) was determined by identifying patients with a confirmed concussion directly correlated with presenting symptoms and for which CST was specifically sought as a treatment option. Demographics and patient-determined treatment duration data were analyzed by comparison groups extensively suggested in existing literature: Recovery time since injury as either Post-acute concussion (<6 months) or Post-Concussion Syndrome (PCS) (≥6 months); Athletes (A) or Non-athletes (NA); and traditional gender. Final PTOS group criteria was determined by eliminating confounding issues reporting (n = 47): (A, n = 24 and NA, n = 23).

RESULTS

Quantitative data was analyzed via Numerical Analysis, and qualitative data was analyzed via Inductive Content Analysis. Symptoms reported in all charts as well as in the PTOS were consistent with identified PCS subtypes. Utilization of CST revealed that most patients determined the treatment effect upon concussion symptoms within 1-3 sessions. Nearly twice as many sessions were attended in the PCS than post-acute groups. Referral sources, studied for a perspective on local concussion after-care discharge planning, ranged from professional to personal recommendation or self-discovery. A majority of patients met goals of reducing post-acute or PCS as reasons cited by self-determined change-in-status or discharge from service. Patients were asked to indicate on the PTOS which pre- and post-treatment symptoms were helped or not helped by this particular intervention.

CONCLUSIONS

Patient-reported changes of PCS symptoms is critical when evaluating treatment options. CST is an experiential treatment that addresses subjective levels of dysfunction, thus it is the patient deciding the value of an intervention. A sizable portion of patients in all groups reported a positive effect upon their symptoms by CST. Patients indicated personal meaning to CST through their utilization of multiple sessions. A high percentage indicated the likelihood of referring others with PCS for CST. Of the 212 patient charts first studied, the 145 not meeting inclusion criteria suggest some chronic conditions may present as long-term effects of older head injuries. CST is a low-risk, conservative treatment option for PCS sub-types worthy of further clinical study.

Blast mild traumatic brain injury is associated with increased myopia and chronic convergence insufficiency

While chronic visual symptom complaints are common among Veterans with a history of mild traumatic brain injury (mTBI), research is still ongoing to characterize the pattern of visual deficits that is most strongly associated with mTBI and specifically, the impact of blast-related mTBI on visual functioning. One area that has not been well explored is the potential impact of blast mTBI on refractive error. While myopic shifts have been documented following head injuries in civilian populations, posttraumatic myopic shifts have not been explored in participants with military mTBI. This study investigated the impact of blast mTBIs on a range of visual function measures including distance acuity and refractive error, in a well-characterized cohort of thirty-one Post-9/11 veterans for whom detailed clinical interviews regarding military and TBI history were available. Seventeen participants had a history of blast-related mTBI (blast mTBI + group) while 14 did not (blast mTBI- group). Results show an increased frequency of convergence insufficiency and myopia in the blast mTBI + group relative to the blast mTBI- group. Linear regression analyses further show that deficits in distance acuity and refractive error are associated with the number of blast mTBIs during military service but not the number of non-blast mTBIs or the number of lifetime non-blast TBIs and cannot be accounted for by PTSD. These results are consistent with long-lasting damage following blast mTBI to subcortical visual structures that support both vergence movements and the accommodative functions needed to see clearly objects at varying distances.

Disparity vergence differences between typically occurring and concussion-related convergence insufficiency pediatric patients

This study sought to test the hypothesis that significant differences would be observed in clinical measures, symptoms, and objective assessments of vergence eye movements between children with typically developing convergence insufficiency (TYP-CI) and children with persistent post-concussion symptoms with convergence insufficiency (PPCS-CI). Data from age-matched binocularly normal controls (BNC) were used for comparison. Data from three groups of children 11 to 17 years of age are presented: BNC (N = 11), TYP-CI (N = 10), and PPCS-CI (N = 15). Clinical measures of vergence, accommodation, and symptom severity were collected. Symmetrical 4° disparity vergence eye movements were quantified with an eye tracker integrated into a head-mounted display (Oculus DK2). Peak velocity and final response amplitude of convergence and divergence eye movement responses were assessed. The mean near point of convergence (break) was more receded (worse), the amplitude of accommodation more deficient, and convergent and divergent peak velocities slower in the PPCS-CI group compared with the TYP-CI and BNC groups. These results suggest that PPCS-CI may be a different clinical entity than TYP-CI. Hence, more research is warranted to determine whether the therapeutic interventions that are effective for TYP-CI can also be used for PPCS-CI populations.

Development and Validation of a Mobile Application to Detect Visual Dysfunction Following Mild Traumatic Brain Injury

INTRODUCTION

Following mild traumatic brain injury, visual dysfunction is a common occurrence, yet the condition often goes undiagnosed. A mobile application was developed to measure aspects of visual acuity and oculomotor function. The aim of this project was to validate the newly developed suite of outcomes conducive for use in the field to detect visual dysfunction.

MATERIALS AND METHODS

A custom mobile application was developed on an Apple iPad using iOS operating system software version 11.0 in Objective C to measure near point of convergence (NPC), distance visual acuity, reading fluency, and self-rated convergence insufficiency (CI). To determine construct validity, 50 healthy young adults were administered NPC and distance visual acuity assessments using the iPad and standard clinical approaches. A ruler measurement was obtained simultaneous to the iPad NPC measurement to determine measurement accuracy. All testing was administered by a licensed optometrist and the order of testing (iPad versus clinical) was randomized.

RESULTS

The correlation coefficient between the iPad and clinical measurements of NPC was 0.893, while iPad and ruler measurement was 0.947. Modest accordance was found between iPad and wall chart measures assessing distance visual acuity. A ceiling effect was evident with use of a wall chart to determine distance visual acuity. Healthy young adults scored a mean (SD) of 13.0 (7.4) on the Convergence Insufficiency Symptom Survey. Reading fluency was highly variable with a mean (SD) of 291 (119) words per minute.

CONCLUSIONS

iPad measures of NPC were highly correlated with clinical measures, while visual acuity measured with the iPad showed modest correlation. Nonetheless, the suite of visual assessments provide value as screening tools, and when used in combination with reading fluency assessment and self-reported CI may be effective in identifying visual dysfunction following mild traumatic brain injury.

The Relationship Between Severe Visual Acuity Loss, Traumatic Brain Injuries, and Ocular Injuries in American Service Members From 2001 to 2015

INTRODUCTION

Although traumatic brain injury (TBI) is known to cause many visual problems, the correlation between the extent of severe visual acuity loss (SVAL) and severity of TBI has not been widely explored. In this retrospective analysis, combined information from Department of Defense (DoD)/Veterans Affairs ocular injury and TBI repositories were used to evaluate the relationship between chronic SVAL, TBI, ocular injuries, and associated ocular sequelae for U.S. service members serving between 2001 and 2015.

MATERIALS AND METHODS

The Defense and Veterans Eye Injury and Vision Registry (DVEIVR) is an initiative led by the DoD and Veterans Affairs that consists of clinical and related data for service members serving in theater since 2001. The Defense and Veterans Brain Injury Center (DVBIC) is the DoD's office for tracking TBI data in the military and maintains data on active-duty service members with a TBI diagnosis since 2000. Longitudinal data from these 2 resources for encounters between February 2001 and October 2015 were analyzed to understand the relation between SVAL, and TBI while adjusting for ocular covariates such as open globe injury (OGI), disorders of the anterior segment and disorders of the posterior segment in a logistic regression model. TBI cases in DVEIVR were identified using DVBIC data and classified according to International Statistical Classification of Diseases criteria established by DVBIC. Head trauma and other open head wounds (OOHW) were also included. SVAL cases in DVEIVR were identified using both International Statistical Classification of Diseases criteria for blindness and low vision as well as visual acuity test data recorded in DVEIVR.

RESULTS

Data for a total of 25,193 unique patients with 88,996 encounters were recorded in DVEIVR from February, 2001 to November, 2015. Of these, 7,217 TBI and 1,367 low vision cases were identified, with 638 patients experiencing both. In a full logistic model, neither UTBI nor differentiated TBI (DTBI, ie, mild, moderate, severe, penetrating, or unclassified) were significant risk factors for SVAL although ocular injuries (disorders of the anterior segment, disorders of the posterior segment, and OGI) and OOHW were significant.

CONCLUSION

Any direct injury to the eye or head risks SVAL but the location and severity will modify that risk. After adjusting for OGIs, OOHW and their sequelae, TBI was found to not be a significant risk factor for SVAL in patients recorded in DVEIVR. Further research is needed to explore whether TBI is associated with more moderate levels of vision acuity loss.

Frequency of oculomotor disorders in adolescents 11 to 17 years of age with concussion, 4 to 12 weeks post injury

The purpose of the study was to determine the frequency of vision diagnoses after concussion in adolescents and evaluate the sensitivity and specificity of physician-administered screening for detecting convergence and accommodative disorders post-concussion. We enrolled participants 11 to 17 years old, assessed 4 to 12 weeks following a diagnosed concussion. During the initial concussion examination, a sports medicine physician measured the near point of convergence (NPC), monocular accommodative amplitude (AA), and symptoms using the Convergence Insufficiency Symptom Survey (CISS). A comprehensive oculomotor evaluation was performed by an optometrist. One hundred and thirteen adolescents were enrolled, with a mean age of 15.2 years. Seventy-nine of the 113 (70%) participants had at least one oculomotor diagnosis after concussion, with the most common problems being vergence disorders (60%) and accommodative disorders (57%). The most common vergence disorder was convergence insufficiency (35%). Among accommodative disorders, the most common problem was accommodative insufficiency (35%). In all, 47% of the participants had more than one oculomotor diagnosis following concussion. The sensitivity of physician screening using measures of NPC, AA, and CISS for detecting convergence and accommodative insufficiency was 63%, 43%, 48%, respectively. The results of this study provide additional evidence that vision problems are common in adolescents with persistent concussion symptoms in the sub-acute phase 4 to 12 weeks post-concussion, and current physician screening methods using the NPC, AA, or the CISS underperform. Thus, it is prudent that adolescents with post-concussion symptoms lasting more than 4 weeks post injury receive a comprehensive oculomotor examination.

Utility of 1 Measurement Versus Multiple Measurements of Near Point of Convergence After Concussion

CONTEXT

Increased near point of convergence (NPC) distance is a common finding after concussion and is associated with physical symptoms and worsened neurocognitive performance. Vestibular/Ocular Motor Screening measures NPC distance across 3 trials and uses the average measurement to inform clinical care. However, whether 3 trials are necessary, are consistent, or add clinical utility is unknown.

OBJECTIVE

To investigate the consistency across 3 trials of NPC and establish the classification accuracy (ie, clinical utility) of 1 or 2 trials compared with the standardized average of 3 trials.

DESIGN

Retrospective cohort study.

SETTING

Sports medicine clinic and research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Consecutively enrolled patients aged 10 to 22 years with diagnosed concussions (74% sport related; n = 380).

MAIN OUTCOME MEASURE(S)

The previously reported clinical cutoff value of ≥5 cm across 3 trials was used. Pearson correlation and intraclass correlation coefficients were used to evaluate agreement between trials and average scores. Reliable change indices (RCIs) using 95% confidence intervals were also calculated.

RESULTS

The Pearson correlation (r = .98) and intraclass correlation (0.98) coefficients revealed excellent agreement between the first measurement and average NPC distance across 3 measurements. The RCI across all trials was 2 cm. When the first NPC measurement was ≤3 cm or ≥7 cm, agreement existed within the RCI between the first measurement and the average of 3 measurements in 99.6% of cases. When we averaged the first and second measurements, 379/380 (99.7%) participants had the same classification (ie, <5 cm = normal, ≥5 cm = abnormal) as the average NPC distance across 3 measurements.

CONCLUSIONS

Our findings suggest limited utility of multiple or average NPC distance measurements when the initial NPC distance is outside of RCI clinical cutoffs (ie, ≤3 cm or ≥7 cm). Given the high consistency between the first measurement and average NPC distance across 3 trials, only 1 measurement of NPC distance is warranted unless the first measurement is between 3 and 7 cm.

Rehabilitation of Sport-Related Concussion

This article provides a summary of clinical assessment methods and nonpharmacologic rehabilitation techniques used for concussed patients. It describes concussion-relevant physical examination methods to identify underlying symptom generators. This approach allows practitioners to prescribe targeted rehabilitation therapies to treat postconcussion symptoms. Evidence-based rehabilitation approaches include cervical rehabilitation, vestibulo-ocular rehabilitation, and sub-symptom threshold aerobic exercise.

Traumatic Brain Injury in Children: Do the Eyes Have It? The Orthoptic Evaluation of Traumatic Brain Injury

Because the neuropathological changes caused by mild traumatic brain injury (mTBI) more often manifest as functional impairments than structural abnormalities, the clinical diagnosis of mTBI may rely too heavily on a combination of history and self-reported symptoms. The mechanism of injury in mild traumatic brain injury (mTBI) predicts that supranuclear pathways controlling eye movement systems would be vulnerable to damage, and diagnostic tests of these systems would be high-yield. In fact, tests of oculomotor function have proven to be highly sensitive in detecting neurological soft signs, but may require expensive, specialized equipment. Fortunately, Certified Orthoptists (COs) are skilled at the evaluation of accommodative dysfunction, abnormalities of saccades, smooth pursuit, and vestibular eye movements, and vergence errors using standard ophthalmic equipment. Because COs are accustomed to adapting the sensorimotor exam to infants and pre-verbal children, they are able to modify or design objective methods, the results of which may be difficult for the patient with a functional overlay to decipher and deceive. When the patient with a history of mTBI presents to the ophthalmologist with visual symptoms and a normal routine eye exam, it is important to order a sensorimotor examination by a CO to confirm the diagnosis.

The integrated functions of the cardiac autonomic and vestibular/oculomotor systems in adolescents following severe traumatic brain injury and typically developing controls

INTRODUCTION

The cardiac autonomic control system (CACS) is frequently impaired post-traumatic brain injury (TBI). However, the prevalence of vestibular/oculomotor impairment is less studied. These two systems interact during position change and contribute to blood-pressure regulation through the vestibulo-sympathetic reflex. Aim: To assess the CACS, the vestibular/oculomotor systems and their integrative function in adolescents post-TBI compared to typically-developing (TD) adolescents. Methods: 19 adolescents in the subacute stage following a severe TBI (14-117 days post injury) and 19 age and sex matched TD controls were recruited. Heart Rate Variability (HRV) was assessed at rest and during a modified tilt-test. A quantified version of the Vestibular/Ocular-Motor Screening (VOMS) was also administered. Results: At rest, the TBI group had higher HR and lower HRV values (p < .001). All participants with TBI demonstrated impairments in the VOMS (median of positive tests: 5 [range 2-9]) compared to only 6 out of 19 in the TD participants (median 0 [0-2]) (z = -5.34; p < .001). In response to the modified tilt test, the HRV increased significantly in the lifting period and decreased significantly once in standing only in the TBI group (z = -2.85, p = .025). Conclusion: Adolescents post severe TBI demonstrated impairments in the CACS, positive tests on the VOMS and significantly greater changes in the modified tilt test as compared to TD. Clinical trial gov. number: NCT03215082.

Reflexive Fusional Vergence and Its Plasticity Are Impaired in Convergence Insufficiency

Purpose

We compared the adaptive capacities of reflexive fusional convergence and divergence in 10 participants with untreated convergence insufficiency (CI) to 10 age-matched binocularly normal controls (BNCs) in an effort to elucidate the functional basis of CI.

Methods

Vergence responses were monitored binocularly at 250 Hz using video-based infrared oculography, while single and double-step disparity stimuli were viewed dichoptically. The double-step stimuli were designed to induce an adaptive increase in the convergence or divergence reflexive fusional response dynamics.

Results

As expected, convergence responses in the CI population were significantly slower at baseline (BNC 12.0 ± 1.8°/s vs. CI 7.4 ± 2.5°/s; P < 0.001), but divergence response velocities were similar between groups (P = 0.38). Critically, we observed an impaired adaptive change in convergence peak velocities in the CI group when compared to BNCs (–18.2% ± 27.3% vs. 25.4% ± 9.8%; P < 0.001). Adaptive changes in reflexive fusional divergence responses were similar between groups (P > 0.5) and significantly less robust when compared to BNC convergence.

Conclusions

The results support the hypothesis that the adaptive capacities of vergence are related to the strength of the underlying reflexive fusional response. Combined, the evidence suggests that the clinical condition of convergence insufficiency is underpinned by an underdeveloped or perturbated reflexive fusional vergence response mechanism. We relate these observations to different clinical guidelines for the management and treatment of this condition.

Distinctive Convergence Eye Movements in an Acquired Neurosensory Dysfunction

In late 2016, diplomats in Havana, Cuba, began presenting with a unique symptom complex after perceiving a strange noise and/or feeling a pressure field in their domicile. This report is a retrospective, quantitative analysis of video-oculography data of pupillary light reflex performance and binocular disparity-driven eye and pupil movements during the acute time period after the reported exposure. The patterns of response in these 19 individuals are markedly different than those seen in a group of individuals with the usual acute mild traumatic brain injury (17 subjects) and from 62 control subjects (21-60 years old) with no injury. Non-linear least squares regression was used to estimate the model parameters from the eye movement and the pupil measurements (1). Linear discriminant analysis was then used to identify a classifier for an objective discrimination of the groups with >91% accuracy and no confusion between the acute neurosensory findings among the members of the Havana diplomatic community and the subjects with acute mild traumatic brain injury. This pattern difference in eye and pupil behavior may be a useful screen to help objectively distinguish blunt trauma from Havana-type effects in the future and to guide the affected individuals to appropriate care.

Accommodation and stereopsis in adults with traumatic brain injury

BACKGROUND

Traumatic brain injury has many adverse effects on visual functions. The aim of this study is to evaluate accommodation, stereopsis deficits and visual symptoms in Chinese patients with traumatic brain injury.

METHODS

This is a cross-sectional study that included 22 patients with traumatic brain injury and 22 controls; the refractive status, stereoacuity, and accommodative ability of each subject were measured.

RESULTS

Patients with traumatic brain injury were significantly more symptomatic than controls (p < 0.001). Near stereoacuity thresholds were significantly elevated in patients with traumatic brain injury compared to controls (p < 0.001). Accommodative amplitude (right eye: p = 0.007; left eye: p = 0.01; both eyes: p = 0.002) and accommodative facility rates (right eye: p < 0.001; left eye: p < 0.001; both eyes: p < 0.001) were significantly lower in patients with traumatic brain injury, for whom there were no significant differences between the accommodative facility rates of the pre- and post-three-minute binocular flipper sessions (p = 0.51). Patients with traumatic brain injury showed greater accommodative lag to 2.5 D (p = 0.03), 3 D (p = 0.03), 4 D (p = 0.004) and 5 D (p = 0.001) stimuli, but not to the 2 D (p = 0.10) stimulus. The regression equation of accommodative lag to stimuli was steeper for the traumatic brain injury group (slope: p = 0.01; y-intercept: p < 0.0001). There were also significant correlations between visual symptoms and clinical findings including binocular accommodative amplitude (r = -0.480, p = 0.001), binocular accommodative facility (r = -0.445, p = 0.004) and stereopsis (r = 0.457, p = 0.002).

CONCLUSION

Patients with traumatic brain injury have deficits in accommodation and stereopsis.

Soft, wireless periocular wearable electronics for real-time detection of eye vergence in a virtual reality toward mobile eye therapies

Recent advancements in electronic packaging and image processing techniques have opened the possibility for optics-based portable eye tracking approaches, but technical and safety hurdles limit safe implementation toward wearable applications. Here, we introduce a fully wearable, wireless soft electronic system that offers a portable, highly sensitive tracking of eye movements (vergence) via the combination of skin-conformal sensors and a virtual reality system. Advancement of material processing and printing technologies based on aerosol jet printing enables reliable manufacturing of skin-like sensors, while the flexible hybrid circuit based on elastomer and chip integration allows comfortable integration with a user's head. Analytical and computational study of a data classification algorithm provides a highly accurate tool for real-time detection and classification of ocular motions. In vivo demonstration with 14 human subjects captures the potential of the wearable electronics as a portable therapy system, whose minimized form factor facilitates seamless interplay with traditional wearable hardware.

Clinical and Functional Imaging Changes Induced from Vision Therapy in Patients with Convergence Insufficiency

Office-Based Vergence/Accommodative Therapy (OBVAT) is an effective treatment for convergence insufficiency (CI) and remediates symptoms in about 75% of patients. Hence, the study of CI patients can serve as a systems-level model to understand the neural mechanisms evoked from rehabilitation. Symptomatic young adult CI patients (N=25) participated in 12 hours of OBVAT and were compared to 25 binocularly normal controls (BNC) using unpaired t-tests. CI patients have significantly lower near point of convergence and positive fusional vergence and were more symptomatic compared to BNC (p<; 0.0001). Using paired t-tests, significant differences (p<; 0.0001) were observed between CI patients' baseline and post-OBVAT measurements where the near point of convergence decreased, positive fusional vergence increased, and the results from the Convergence Insufficiency Symptom Survey (CISS) decreased. Using paired t-tests, the mean beta weights of the functional activity significantly increased for the frontal eye fields (p<; 0.01) and the oculomotor vermis (p<; 0.05) for CI patients post-OBVAT compared to baseline measurements. These data demonstrate that OBVAT increases functional activity within the brain and improves clinical function and visual symptoms in CI patients.

Test-Retest Reliability of Functional Magnetic Resonance Imaging Activation for a Vergence Eye Movement Task

Vergence eye movements are the inward and outward rotation of the eyes responsible for binocular coordination. While studies have mapped and investigated the neural substrates of vergence, it is not well understood whether vergence eye movements evoke the blood oxygen level-dependent signal reliably in separate experimental visits. The test-retest reliability of stimulus-induced vergence eye movement tasks during a functional magnetic resonance imaging (fMRI) experiment is important for future randomized clinical trials (RCTs). In this study, we established region of interest (ROI) masks for the vergence neural circuit. Twenty-seven binocularly normal young adults participated in two functional imaging sessions measured on different days on the same 3T Siemens scanner. The fMRI experiments used a block design of sustained visual fixation and rest blocks interleaved between task blocks that stimulated eight or four vergence eye movements. The test-retest reliability of task-activation was assessed using the intraclass correlation coefficient (ICC), and that of spatial extent was assessed using the Dice coefficient. Functional activation during the vergence eye movement task of eight movements compared to rest was repeatable within the primary visual cortex (ICC = 0.8), parietal eye fields (ICC = 0.6), supplementary eye field (ICC = 0.5), frontal eye fields (ICC = 0.5), and oculomotor vermis (ICC = 0.6). The results demonstrate significant test-retest reliability in the ROIs of the vergence neural substrates for functional activation magnitude and spatial extent using the stimulus protocol of a task block stimulating eight vergence eye movements compared to sustained fixation. These ROIs can be used in future longitudinal RCTs to study patient populations with vergence dysfunctions.

Ocular changes in traumatic brain injury: A review

Traumatic brain injury is represented by a penetrating or non-penetrating head injury, which causes disruption in the normal functioning of the brain. Traumatic brain injury has been an ardently debated topic of discussion due to its prevalence in media centric persons such as military personnel and athletes. Current assessments for traumatic brain injury have looked at vestibulo-ocular and vascular parameters to aid in diagnosis. Innovations in non-invasive ophthalmic imaging have allowed for the visualization of specific tissue structure/function relationships in a variety of ophthalmic and neurodegenerative diseases. As the eye and brain share significant embryological and physiological pathways, ocular imaging modalities may provide a novel and impactful tool in advancing assessment of traumatic brain injury. Herein, we examined the available literature and data on visual fields, mean retinal nerve fiber layer thickness, retinal ganglion cell layer thickness, and cerebral blood flow following traumatic brain injury. This review of published individual and population-based studies was performed in order to explore the feasibility and importance of considering ocular imaging biomarkers following traumatic brain injury.

Case Studies in Neuroscience: Instability of the visual near triad in traumatic brain injury-evidence for a putative convergence integrator

Deficits of convergence and accommodation are common following traumatic brain injury, including mild traumatic brain injury, although the mechanism and localization of these deficits have been unclear and supranuclear control of the near-vision response has been incompletely understood. We describe a patient who developed profound instability of the near-vision response with inability to maintain convergence and accommodation following mild traumatic brain injury, who was identified to have a structural lesion on brain MRI in the pulvinar of the caudal thalamus, the pretectum, and the rostral superior colliculus. We discuss the potential relationship between posttraumatic clinical near-vision response deficits and the MRI lesion in this patient. We further propose that the MRI lesion location, specifically the rostral superior colliculus, participates in neural integration for convergence holding, given its proven anatomic connections with the central mesencephalic reticular formation and C-group medial rectus motoneurons in the oculomotor nucleus, which project to extraocular muscle nontwitch fibers specialized for fatigue-resistant, slow, tonic activity such as vergence holding.NEW & NOTEWORTHY Supranuclear control of the near-vision response has been incompletely understood to date. We propose, based on clinical and anatomic evidence, functional pathways for vergence that participate in the generation of the near triad, "slow vergence," and vergence holding.

Vergence Endurance Test: A Pilot Study for a Concussion Biomarker

The Vergence Endurance Test (VET), a quantitative and objective eye movement assessment, was utilized to differentiate control from concussed subjects. Nine symptomatic concussed (2 male; 30.8 ± 11 years) and 9 asymptomatic control (6 male; 25.1 ± 1.4 years) subjects participated in the VET. Symmetrical disparity vergence step targets were presented with and without visual distractors. A masked data analyst measured vergence latency, peak velocity, response amplitude, settling time, and the percentage of trials which contained blinks. A Binocular Precision Index (BPI) and a Binocular Accuracy Index (BAI) were calculated to quantify the changes that occur in the vergence parameters over the duration of the VET. Convergence and divergence peak velocity, divergence response amplitude, the percentage of trials that contained blinks during the transient portion of the response, and the BAI were significantly (p < 0.05) different between the concussed and the control subjects. For these parameters, the BAI and divergence response amplitude yielded the greatest accuracy, 78%, in their ability to discriminate between the groups. The VET objectively measures the change in vergence performance over time and shows promise as a method to diagnose a concussion. Future studies will determine whether the VET can be used to assess the extent of natural recovery and the effectiveness of therapeutic interventions.

Amelioration of visual deficits and visual system pathology after mild TBI with the cannabinoid type-2 receptor inverse agonist SMM-189

Mild TBI is often accompanied by visual system dysfunction and injury, which is at least partly caused by microglial neuroinflammatory processes initiated by the injury. Using our focal cranial blast mouse model of closed-skull mild TBI, we evaluated the ability of the cannabinoid type-2 (CB2) receptor inverse agonist SMM-189, which biases microglia from the harmful M1 state to the beneficial M2 state, to mitigate visual system dysfunction and injury after TBI. Male C57BL/6 or Thy1-EYFP reporter mice received a closed-head blast of either 0-psi (sham) or 50-psi to the left side of the cranium. Blast mice received vehicle or 6 mg/kg SMM-189 daily beginning 2 h after blast. Sham mice received vehicle. In some mice, retina and optic nerve/tract were assessed morphologically at 3-7 days after blast, while other mice were assessed functionally by Optomotry 30 days after blast and morphologically at ≥30 days after blast. Mice sacrificed at 3-7 days were treated daily until sacrificed, while those assessed ≥30 days after blast were treated daily for 2 weeks post blast. Axon damage was evident in the left optic nerve and its continuation as the right optic tract at 3 days post blast in vehicle-treated blast mice in the form of swollen axon bulbs, and was accompanied by a significant increase in the abundance of microglia. Testing at 30 days post blast revealed that the contrast sensitivity function was significantly reduced in both eyes in vehicle-treated blast mice compared to vehicle-treated sham blast mice, and axon counts at ≥30 days after blast revealed a ∼10% loss in left optic nerve in vehicle-treated blast mice. Left optic nerve axon loss was highly correlated with the left eye deficit in contrast sensitivity. Immunolabeling at 30 days post blast showed a significant increase in the abundance of microglia in the retinas of both eyes and in GFAP + Müller cell processes traversing the inner plexiform layer in the left eye of vehicle-treated blast mice. SMM-189 treatment reduced axon injury and microglial abundance at 3 days, and mitigated axon loss, contrast sensitivity deficits, microglial abundance, and Müller cell GFAP upregulation at ≥30 days after blast injury. Analysis of right optic tract microglia at 3 days post blast for M1 versus M2 markers revealed that SMM-189 biased microglia toward the M2 state, with this action of SMM-189 being linked to reduced axonal injury. Taken together, our results show that focal left side cranial blast resulted in impaired contrast sensitivity and retinal pathology bilaterally and optic nerve loss ipsilaterally. The novel cannabinoid drug SMM-189 significantly mitigated the functional deficit and the associated pathologies. Our findings suggest the value of combatting visual system injury after TBI by using CB2 inverse agonists such as SMM-189, which appear to target microglia and bias them away from the pro-inflammatory M1 state, toward the protective M2 state.

Rehabilitation Assessment and Management of Neurosensory Deficits After Traumatic Brain Injury in the Polytrauma Veteran

Neurosensory deficits after traumatic brain injury can frequently lead to disability; therefore, diagnosis and treatment are important. Posttraumatic headaches typically resemble migraines and are managed similarly, but adjuvant physical therapy may be beneficial. Sleep-related issues are treated pharmacologically based on the specific sleep-related complaint. Fatigue is difficult to treat; cognitive behavioral therapy and aquatic therapy can be beneficial. Additionally, methylphenidate and modafinil have been used. Peripheral and central vestibular dysfunction causes dizziness and balance dysfunction, and the mainstay of treatment is vestibular physical therapy. Visual dysfunction incorporates numerous different diagnoses, which are frequently treated with specific rehabilitation programs.

Vision Rehabilitation After Traumatic Brain Injury

Visual dysfunctions and symptoms are commonly experienced after even mild traumatic brain injury (TBI) despite excellent visual acuity. All individuals who have experienced a TBI/concussion should be screened for vision symptoms and visual dysfunction. A TBI-specific eye examination is necessary to identify the visual sequelae of TBI and address any vision/ocular issues that may be contributing to other post-TBI complaints. A vision rehabilitation plan that includes vision therapy can improve visual dysfunction secondary to TBI. Combining office-based and home-based vision therapy training will maximize visual potential and functional results.

Effects of visual distractors on vergence eye movements

Visual attention is an important aspect of everyday life, which can be incorporated in the assessment of many diagnoses. Another important characteristic of visual attention is that it can be improved via therapeutic interventions. Fifteen subjects with normal binocular vision were presented with visual distractor stimuli at various spatial locations while initiating disparity vergence eye movements (inward or outward rotation of eyes) within a haploscope system. First, a stationary distractor stimulus was presented in either the far, middle, or near visual spaces while the subjects were instructed to follow a target stimulus that was either stationary, converging (moving toward subject), or diverging (moving away from subject). For the second experiment, a dynamic distractor stimulus within the far, middle, or near visual space that was converging or diverging was presented while the target stimulus was also converging or diverging. The subjects were instructed to visually follow the target stimulus and ignore the distractor stimulus. The vergence responses had a final vergence angle between the target and distractor stimuli which has been termed a center of gravity (CoG) effect. Statistically significant differences were observed between the convergence peak velocities (p < 0.001) and response amplitudes (p < 0.001) comparing responses without distractors to responses with the presence of a vergence distractor. The results support that vergence eye movements are influenced by visual distractors, which is similar to how distractors influence saccadic eye movements. The influence of visual distractors within vergence eye movements may be useful to assess binocular dysfunction and visual distraction which are common post brain injury.

Visual problems associated with traumatic brain injury

Traumatic brain injury (TBI) and its associated concussion are major causes of disability and death. All ages can be affected but children, young adults and the elderly are particularly susceptible. A decline in mortality has resulted in many more individuals living with a disability caused by TBI including those affecting vision. This review describes: (1) the major clinical and pathological features of TBI; (2) the visual signs and symptoms associated with the disorder; and (3) discusses the assessment of quality of life and visual rehabilitation of the patient. Defects in primary vision such as visual acuity and visual fields, eye movement including vergence, saccadic and smooth pursuit movements, and in more complex aspects of vision involving visual perception, motion vision ('akinopsia'), and visuo-spatial function have all been reported in TBI. Eye movement dysfunction may be an early sign of TBI. Hence, TBI can result in a variety of visual problems, many patients exhibiting multiple visual defects in combination with a decline in overall health. Patients with chronic dysfunction following TBI may require occupational, vestibular, cognitive and other forms of physical therapy. Such patients may also benefit from visual rehabilitation, including reading-related oculomotor training and the prescribing of spectacles with a variety of tints and prism combinations.

Longitudinal changes in oculomotor function in young adults with mild traumatic brain injury in Sweden: an exploratory prospective observational study

OBJECTIVES

To assess (1) whether visual disturbances can be demonstrated with objective measures more often in patients with mild traumatic brain injury (mTBI) than in orthopaedic controls and non-injured controls, (2) whether such objectively demonstrated disturbances change over time and (3) whether self-reported visual symptoms after mTBI correlate with objectively measurable changes in visuomotor performance.

DESIGN

A prospective, controlled, observational study, with assessments planned 7-10 and 75-100 days after injury.

SETTING

Emergency department of a general hospital in Sweden.

PARTICIPANTS

15 patients with mTBI, 15 patients with minor orthopaedic injury, 15 non-injured controls, aged 18-40 years.

OUTCOME MEASURES

Visual examination, including assessment of visual acuity, accommodation, eye alignment, saccades and stereoacuity. Symptom assessment using Convergence Insufficiency Symptoms Survey (CISS) and Rivermead PostConcussion Symptoms Questionnaire.

RESULTS

Assessments were performed 4-13 and 81-322 days after injury (extended time frames for logistical reasons). No statistically significant difference was found between the mTBI and control groups regarding saccade performance and stereoacuity at any time point. The accommodative amplitude was significantly lower in the mTBI group compared with non-injured controls at baseline. 6 out of 13 patients with mTBI had accommodative insufficiency at follow-up. Near point of convergence in the mTBI group was receded at baseline and improved statistically significantly at follow-up. At baseline, patients with mTBI had significantly higher CISS score than orthopaedic and non-injured controls. For patients with mTBI, the CISS score correlated with fusional vergence.

CONCLUSION

There were some transient measurable visual changes regarding convergence in patients with mTBI during the subacute period after the injury. Our findings of persistence of accommodative insufficiency in a considerable proportion of patients with mTBI suggest that this visual function should not be overlooked in clinical assessment.

Objective Assessment of Vergence after Treatment of Concussion-Related CI: A Pilot Study

PURPOSE

To evaluate changes in objective measures of disparity vergence after office-based vision therapy (OBVT) for concussion-related convergence insufficiency (CI) and determine the feasibility of using this objective assessment as an outcome measure in a clinical trial.

METHODS

This was a prospective, observational trial. All participants were treated with weekly OBVT with home reinforcement. Participants included two adolescents and three young adults with concussion-related, symptomatic CI. The primary outcome measure was average peak velocity for 4° symmetrical convergence steps. Other objective outcome measures of disparity vergence included time to peak velocity, latency, accuracy, settling time, and main sequence. We also evaluated saccadic eye movements using the same outcome measures. Changes in clinical measures (near point of convergence, positive fusional vergence at near, Convergence Insufficiency Symptom Survey [CISS] score) were evaluated.

RESULTS

There were statistically significant and clinically meaningful changes in all clinical measures for convergence. Four of the five subjects met clinical success criteria. For the objective measures, we found a statistically significant increase in peak velocity, response accuracy to 4° symmetrical convergence and divergence step stimuli, and the main sequence ratio for convergence step stimuli. Objective saccadic eye movements (5 and 10°) appeared normal pre-OBVT and did not show any significant change after treatment.

CONCLUSIONS

This is the first report of the use of objective measures of disparity vergence as outcome measures for concussion-related convergence insufficiency. These measures provide additional information that is not accessible with clinical tests about underlying physiological mechanisms leading to changes in clinical findings and symptoms. The study results also demonstrate that patients with concussion can tolerate the visual demands (over 200 vergence and versional eye movements) during the 25-minute testing time and suggest that these measures could be used in a large-scale randomized clinical trial of concussion-related CI as outcome measures.