Convergence insufficiency in brain-injured patients

Post-Traumatic Craniocervical Disorders From a Postural Control Perspective: A Narrative Review

Mild traumatic brain injury (mTBI) and whiplash injury (WI) may lead to long-term disabling consequences known as post-concussive syndrome (PCS) and whiplash-associated disorders (WADs). PCS and WAD patients commonly complain of conditions encompassing dizziness, vertigo, headache, neck pain, visual complaints, anxiety, and neurocognitive dysfunctions. A proper medical work-up is a priority in order to rule out any acute treatable consequences. However investigations may remain poorly conclusive. Gathered in the head and neck structures, the ocular sensorimotor, the vestibular, and the cervical proprioceptive systems, all involved in postural control, may be damaged by mTBI or WI. Their dysfunctions are associated with a wide range of functional disorders including symptoms reported by PCS and WAD patients. In addition, the stomatognathic system needs to be specifically assessed particularly when associated to WI. Evidence for considering the post-traumatic impairment of these systems in PCS and WAD-related symptoms is still lacking but seems promising. Furthermore, few studies have considered the assessment and/or treatment of these widely interconnected systems from a comprehensive perspective. We argue that further research focusing on consequences of mTBI and WI on the systems involved in the postural control are necessary in order to bring new perspective of treatment.

Concussed patients with visually induced dizziness exhibit increased ocular torsion and vertical vergence during optokinetic gaze-stabilization

Visually Induced Dizziness (VID) is a common post-concussion sequalae that remains poorly understood and difficult to quantify. The present study aims to identify biomarkers for VID in the form of gaze-stabilizing eye movements. Nine patients with post-commotio VID and nine age-matched healthy controls were recruited by physiotherapists at a local neurorehabilitation centre. Torsional and vergence eye movements were recorded while participants viewed a series of optokinetic rotations where the central- and peripheral regions moved coherently, incoherently, or semi-randomly. Results showed that vergence and torsional velocities were increased in VID patients, reflecting increased oculomotor gain to visual motion, and that responses correlated with symptom severity. Coherent stimulation produced fastest torsional slow-phases across all participants; when faced with confliction directional information, eye movements tended to follow the direction of the central visual field, albeit at slower velocities than during coherent motion, meaning that while torsion was sensitive to visual content of the entire visual field it expressed directional preference to the central stimulation. In conclusion, post-commotio VID was associated with faster slow-phases during optokinetic gaze-stabilization, with both vergence and torsion being correlated to symptom intensity. As torsional tracking remains inaccessible using commercial eye-trackers, vertical vergence may prove particularly accessible for clinical utility.

Eye Movements in Mild Traumatic Brain Injury: Ocular Biomarkers

Mild traumatic brain injury (mTBI, or concussion), results from direct and indirect trauma to the head (i.e. a closed injury of transmitted forces), with or without loss of consciousness. The current method of diagnosis is largely based on symptom assessment and clinical history. There is an urgent need to identify an objective biomarker which can not only detect injury, but inform prognosis and recovery. Ocular motor impairment is argued to be ubiquitous across mTBI subtypes and may serve as a valuable clinical biomarker with the recent advent of more affordable and portable eye tracking technology. Many groups have positively correlated the degree of ocular motor impairment to symptom severity with a minority attempting to validate these findings with diffusion tract imaging and functional MRI. However, numerous methodological issues limit the interpretation of results, preventing any singular ocular biomarker from prevailing. This review will comprehensively describe the anatomical susceptibility, clinical measurement, and current eye tracking literature surrounding saccades, smooth pursuit, vestibulo-ocular reflex, vergence, pupillary light reflex, and accommodation in mTBI.

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.

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.

Ocular Causes for Headache

Ocular causes of headaches include headaches associated with refractive error (HARE), convergence insufficiency (CI), and accommodative spasm (AS). HARE is more severe in patients with a high amount of refractive error. CI or AS patients can have diplopia and strabismus. Both CI and AS can be associated with head trauma or other systemic disorders. Headaches due to ocular causes are frontally localized occurring near the end of the day and are associated with increased amount of near work. HARE is treated with glasses while CI or AS may need other therapies such as prism, eye drops, surgery, or orthoptic exercises.

Rehabilitation of visual disorders

While there is a long history of rehabilitation for motor deficits following cerebral lesions, less is known about our ability to improve visual deficits. Vision therapy, prisms, occluders, and filters have been advocated for patients with mild traumatic brain injury, on the premise that some of their symptoms may reflect abnormal visual or ocular motor function, but the evidence for their efficacy is modest. For hemianopia, attempts to restore vision have had unimpressive results, though it appears possible to generate blindsight through training. Strategic approaches that train more efficient use of visual search in hemianopia have shown consistent benefit in visual function, while prism aids may help some patients. There are many varieties of alexia. Strategic adaptation of saccades can improve hemianopic alexia, but there has been less work and mixed results for pure alexia, neglect dyslexia, attentional dyslexia, and the central dyslexias. A number of approaches have been tried in prosopagnosia, with recent studies of small groups suggesting that face perception of prosopagnosic subjects can be enhanced through perceptual learning.

Visual profile of acquired brain injury in Indian cohort: a retrospective study

OBJECTIVE

With the increasing global prevalence of acquired brain injury (ABI), the burden of visual problems as a sequelae to ABI is on the rise. This study reports the visual profile of patients with ABI seen in Neuro-Optometry Clinic (NOC) at a tertiary eye-care center in Southern India.

METHODS

A retrospective study was carried out between January 2014 and December 2015. Medical records of patients diagnosed with ABI referred by Neuro-Ophthalmologists to the NOC were reviewed. The detailed history, clinical findings of neuro assessment and management details were recorded.

RESULTS

Of the 241 patients with ABI, 208 had Traumatic Brain Injury (TBI) and 33 had Cerebro-Vascular Accident (CVA). The mean (SD) age of patients with TBI was 35 ± 14 years and CVA was 52 ± 16 years. Binocular diplopia (61%) was seen predominantly in TBI due to vertical deviation (31%). Cranial nerve palsy was most common in TBI (55%) than CVA (36%) and visual field defects were most frequently seen in CVA (27%).

CONCLUSION

Cranial nerve paresis and restrictive strabismus with diplopia were the most common presentations in TBI and visual field defects in CVA. A neuro-optometric evaluation is recommended to identify visual dysfunctions and provide appropriate management options.

ABBREVIATIONS

ABI: Acquired Brain Injury; TBI: Traumatic Brain Injury; CVA: Cerebrovascular Accident; NOC: Neuro-Optometry Clinic; NSBVA: Non-Strabismic binocular vision anomalies; OMD: Oculomotor dysfunction; VFD: Visual field defect; GON: Glaucomatous optic neuropathy.

Correlation between Ocular and Vestibular Abnormalities and Convergence Insufficiency in Post-Concussion Syndrome

The vestibular and oculomotor/visual systems are commonly affected in post-concussion syndrome (PCS). Convergence insufficiency (CI) is the most common ocular abnormality after concussion. Electrovestibulography (EVestG) is a relatively new non-invasive method that measures the peripheral vestibular responses; it has shown abnormal vestibular responses in a PCS. Here, we report the results of investigating the correlation between the vestibular and oculomotor systems in PCS population using EVestG and CI measures. Forty-eight PCS patients were tested using EVestG, out of which 20 also completed the Rivermead post-concussion questionnaire (RPQ). An EVestG feature (Field Potential (FP)-area) was extracted from the stationary part of the EVestG signals. A neuro-ophthalmologist (author BM) measured participants' CI at near vision using cross-cover examination and a prism-bar. Results indicate: (1) vestibular abnormality (i.e. FP-area) and CI values are significantly correlated in PCS (R = 0.68, p < .01), and (2) there are significant correlations between severity of concussion (i.e. RPQ3) and CI (R = 0.70, p < .01) and between RPQ3 and FP-area (R = -0.56, p < .02). To the best of our knowledge, this is the first study that objectively demonstrates a significant positive correlation between the CI and vestibular systems' abnormality. These findings are scientifically important as they help localise the pathology of PCS, and are clinically valuable as they help physicians in their decision-making about PCS diagnosis and rehabilitation strategies.

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.

Working memory load improves diagnostic performance of smooth pursuit eye movement in mild traumatic brain injury patients with protracted recovery

Smooth pursuit eye movements have been investigated as a diagnostic tool for mild traumatic brain injury (mTBI). However, the degree to which smooth pursuit differentiates mTBI patients from healthy controls (i.e. its diagnostic performance) is only moderate. Our goal was to establish if simultaneous performance of smooth pursuit and a working memory task increased the diagnostic performance of pursuit metrics following mTBI. We integrated an n-back task with two levels of working memory load into a pursuit target, and tested single- and dual-task pursuit in mTBI patients and healthy controls. We assessed pursuit using measures of velocity accuracy, positional accuracy and positional variability. The mTBI group had higher pursuit variability than the control group in all conditions. Performing a concurrent 1-back task decreased pursuit variability for both the mTBI and control groups. Performing a concurrent 2-back task produced differential effects between the groups: Pursuit variability was significantly decreased in the control group, but not in the mTBI group. Diagnostic indices were improved when pursuit was combined with the 2-back task, and increased by 20% for the most sensitive variable. Smooth pursuit with simultaneous working memory load may be a superior diagnostic tool for mTBI than measuring smooth pursuit alone.

Visually Evoked Potential Markers of Concussion History in Patients with Convergence Insufficiency

Purpose

We investigated whether differences in the pattern visual evoked potentials exist between patients with convergence insufficiency and those with convergence insufficiency and a history of concussion using stimuli designed to differentiate between magnocellular (transient) and parvocellular (sustained) neural pathways.

Methods

Sustained stimuli included 2-rev/s, 85% contrast checkerboard patterns of 1- and 2-degree check sizes, whereas transient stimuli comprised 4-rev/s, 10% contrast vertical sinusoidal gratings with column width of 0.25 and 0.50 cycles/degree. We tested two models: an a priori clinical model based on an assumption of at least a minimal (beyond instrumentation’s margin of error) 2-millisecond lag of transient response latencies behind sustained response latencies in concussed patients and a statistical model derived from the sample data.

Results

Both models discriminated between concussed and nonconcussed groups significantly above chance (with 76% and 86% accuracy, respectively). In the statistical model, patients with mean vertical sinusoidal grating response latencies greater than 119 milliseconds to 0.25-cycle/degree stimuli (or mean vertical sinusoidal latencies >113 milliseconds to 0.50-cycle/degree stimuli) and mean vertical sinusoidal grating amplitudes of less than 14.75 mV to 0.50-cycle/degree stimuli were classified as having had a history of concussion. The resultant receiver operating characteristic curve for this model had excellent discrimination between the concussed and nonconcussed (area under the curve = 0.857; P < .01) groups with sensitivity of 0.92 and specificity of 0.80.

Conclusions

The results suggest a promising electrophysiological approach to identifying individuals with convergence insufficiency and a history of concussion.

A Positive Vestibular/Ocular Motor Screening (VOMS) Is Associated With Increased Recovery Time After Sports-Related Concussion in Youth and Adolescent Athletes

BACKGROUND

Vestibular and ocular motor impairments are routinely reported in patients with sports-related concussion (SRC) and may result in delayed return to play (RTP). The Vestibular/Ocular Motor Screening (VOMS) assessment has been shown to be consistent and sensitive in identifying concussion when used as part of a comprehensive examination. To what extent these impairments or symptoms are associated with length of recovery is unknown.

PURPOSE

To examine whether symptom provocation or clinical abnormality in specific domains of the VOMS results in protracted recovery (time from SRC to commencement of RTP protocol).

STUDY DESIGN

Cohort study (prognosis); Level of evidence, 2.

METHODS

A retrospective chart review was conducted of 167 patients (69 girls, 98 boys; mean ± SD age, 15 ± 2 years [range, 11-19 years]) presenting with SRC in 2014. During the initial visit, VOMS was performed in which symptom provocation or clinical abnormality (eg, unsmooth eye movements) was documented by use of a dichotomous scale (0 = not present, 1 = present). The VOMS used in this clinic consisted of smooth pursuits (SMO_PUR), horizontal and vertical saccades (HOR_SAC and VER_SAC), horizontal and vertical vestibular ocular reflex (HOR_VOR and VER_VOR), near point of convergence (NPC), and accommodation (ACCOM). Domains were also categorized into ocular motor (SMO_PUR, HOR_SAC, VER_SAC, NPC, ACCOM) and vestibular (HOR_VOR, VER_VOR). Cox proportional hazard models were used to explore the relationship between the domains and recovery. Alpha was set at P ≤ .05.

RESULTS

Symptom provocation and/or clinical abnormality in all domains except NPC ( P = .107) and ACCOM ( P = .234) delayed recovery (domain, hazard ratio [95% CI]: SMO_PUR, 0.65 [0.47-0.90], P = .009; HOR_SAC, 0.68 [0.50-0.94], P = .018; VER_SAC, 0.55 [0.40-0.75], P < .001; HOR_VOR, 0.68 [0.49-0.94], P = .018; VER_VOR, 0.60 [0.44-0.83], P = .002). The lowest crude hazard ratio was for ocular motor category (0.45 [0.32-0.63], P < .001).

CONCLUSION

These data suggest that symptom provocation/clinical abnormality associated with all domains except NPC and ACCOM can delay recovery after SRC in youth and adolescents. Thus, the VOMS not only may augment current diagnostic tools but also may serve as a predictor of recovery time in patients with SRC. The findings of this study may lead to more effective prognosis of concussion in youth and adolescents.

Prediction of occupational disability from psychological and neuropsychological evidence in forensic context

Within the fields of psychiatry, psychology, and neuropsychology, medical examiners are often tasked with providing an opinion about an injured individual's health prognosis and likelihood of returning to work. Traditionally, examiners have conducted such assessments by employing clinical intuition, expert knowledge, and judgment. More recently, however, an accumulation of research on factors predictive of disability has allowed examiners to provide prognostications using specific empirically supported evidence. This paper integrates current evidence for four common clinical issues encountered in forensic assessments-musculoskeletal pain, depression, Posttraumatic Stress Disorder, and traumatic brain injury. It discusses an evidence-informed, cross-diagnostic and multifactorial model of predicting disability that is emerging from the literature synthesis, along with recommendations for best forensic assessment practice.

Traumatic brain injury and vestibulo-ocular function: current challenges and future prospects

Normal function of the vestibulo-ocular reflex (VOR) coordinates eye movement with head movement, in order to provide clear vision during motion and maintain balance. VOR is generated within the semicircular canals of the inner ear to elicit compensatory eye movements, which maintain stability of images on the fovea during brief, rapid head motion, otherwise known as gaze stability. Normal VOR function is necessary in carrying out activities of daily living (eg, walking and riding in a car) and is of particular importance in higher demand activities (eg, sports-related activities). Disruption or damage in the VOR can result in symptoms such as movement-related dizziness, blurry vision, difficulty maintaining balance with head movements, and even nausea. Dizziness is one of the most common symptoms following traumatic brain injury (TBI) and is considered a risk factor for a prolonged recovery. Assessment of the vestibular system is of particular importance following TBI, in conjunction with oculomotor control, due to the intrinsic neural circuitry that exists between the ocular and vestibular systems. The purpose of this article is to review the physiology of the VOR and the visual-vestibular symptoms associated with TBI and to discuss assessment and treatment guidelines for TBI. Current challenges and future prospects will also be addressed.

Near Point of Convergence After a Sport-Related Concussion: Measurement Reliability and Relationship to Neurocognitive Impairment and Symptoms

BACKGROUND

Convergence insufficiency (CI) is a common binocular vision deficit after a sport-related concussion (SRC). CI may result in visual discomfort and vision-mediated functional difficulties such as slowed reading and compromised attention, leading to impaired academic, work, and sport performance.

PURPOSE

To test the reliability of repeated near point of convergence (NPC) measurements in a sample of athletes after an SRC; compare the symptoms and cognitive impairment of athletes with normal NPC to those with CI after an SRC; and explore the relationship among age, sex, learning disability, migraine history, and CI.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 78 athletes (mean age, 14.31 ± 2.77 years) who were seen a mean 5.79 ± 5.63 days after an SRC were administered 3 trials of an NPC assessment, along with neurocognitive (Immediate Post-Concussion Assessment and Cognitive Testing [ImPACT]) and symptom assessments. Patients were divided into normal NPC (NPC ≤ 5 cm; n = 45) and CI (NPC >5 cm; n = 33) groups. Intraclass correlation coefficients (ICCs) and repeated-measures analyses of variance (ANOVAs) assessed the consistency of NPC across the 3 trials. The ANOVAs were employed to examine differences on neurocognitive composites and symptoms between the normal NPC and CI groups. Stepwise regressions (controlling for age and symptom scores on the Post-Concussion Symptom Scale [PCSS]) were conducted to evaluate the predictive utility of the NPC distance for neurocognitive impairment.

RESULTS

Groups did not differ on demographic or injury characteristics. NPC differed between trial 1 and trials 2 (P = .02) and 3 (P = .01) for the CI group but not the normal NPC group. Internal consistency was high across NPC measurements (ICC range, 0.95-0.98). Patients with CI performed worse on verbal memory (P = .02), visual motor speed (P = .02), and reaction time (P = .001, η(2) = .13) and had greater total symptom scores (P = .02) after the injury. Results of hierarchical regression revealed that the NPC distance contributed significantly to the model for reaction time (P < .001).

CONCLUSION

CI was common (~42%) in athletes evaluated within 1 month after an SRC. Athletes with CI had worse neurocognitive impairment and higher symptom scores than did those with normal NPC. Clinicians should consider routinely screening for NPC as part of a comprehensive concussion evaluation to help inform treatment recommendations, academic accommodations, and referrals for vision therapy.

The 20/20 patient who can't read

To understand how reading can be disrupted in patients with good acuity, it is important to realize the complexities that underlie this task, which normally seems so effortless. The process of reading is an interplay among vision, eye movements, attention, and linguistic processing, and impairments in any of these functions can result in reduced reading efficiency. The goal of this review is to provide a systematic review of these functions that can help clinicians generate a logical and useful differential diagnosis of impaired reading in the patient with 20/20 vision.

Disorders of Accommodative Convergation and Accommodation (AC/A) Relations at Traumatic Brain Injury

Introduction:

Accommodative Convergence/Accommodation (AC/A) ratio is constant at one and the same person in the course of life, i.e. the same ratio accommodative convergence monitor any change in accommodation measured in diopters. Such a perfect relationship is possible if there are no refractive anomalies in both eyes and oculomotor imbalance of eye muscles.

Material and methods:

We are examined 50 patients with close brain injury, and patients which had problems with near vision, accommodation and convergency were reducted, with loss motor fussion, and preserved stereoscopis vision, and showed us, that disturbances are clear motor and folowed with incapable of patient to hold of superposition view to watching object.

Results:

The difference in average proximity distance vision and reading time with no fatigue after 6 months a statistically significant, the value of t-test, t = 1873 for p <0.01, r = 0. 718. The value of convergent fusion 6 months after treatment in 30% of the patients was from 0 to16 Pd, S. D. = 18. 6, and χ² = 7. 22. In 18% of the patients was from 0 to 10 Pd, S. D = 17. 61, and χ² = 5. 41, at 20% of patients 0 to 22 Pd, SD = 14. 18, χ² = 6. 84, in 16% of patients 0 to 4 Pd, SD = 16. 41, χ² t-test = 5. 13 and the remaining 16% of patients the value of convergent fusion is about 1 PD, S. D = 15. 01, χ² t = 5. 18. All patients showed significant improvement in near vision compared to the value of convergent fusion before treatment where χ² t-test = 9.41, after 6 months of treatment, there is considerable significance p < 0 01, t–test 0. 914, correlation coefficient r = 0. 881.

Conclusion:

Disturbances of AC / A ratio should be evaluated only with regard to all symptoms and is only possible by proper rating interference in reading.

The neuro-ophthalmology of head trauma

SUMMARY

Traumatic brain injury (TBI) is a major cause of morbidity and mortality. Concussion, a form of mild TBI, might be associated with long-term neurological symptoms. The effects of TBI and concussion are not restricted to cognition and balance. TBI can also affect multiple aspects of vision; mild TBI frequently leads to disruptions in visual functioning, while moderate or severe TBI often causes structural lesions. In patients with mild TBI, there might be abnormalities in saccades, pursuit, convergence, accommodation, and vestibulo-ocular reflex. Moderate and severe TBI might additionally lead to ocular motor palsies, optic neuropathies, and orbital pathologies. Vision-based testing is vital in the management of all forms of TBI and provides a sensitive approach for sideline or post-injury concussion screening. One sideline test, the King-Devick test, uses rapid number naming and has been tested in multiple athlete cohorts.

Development of a mild traumatic brain injury-specific vision screening protocol: a Delphi study

Although traumatic brain injury (TBI) can happen to anyone at any time, the wars in Iraq and Afghanistan have brought it renewed attention. Fortunately, most cases of TBI from the recent conflicts are mild TBI (mTBI). Still, many physical, psychological, and social problems are associated with mTBI. Among the difficulties encountered are oculomotor and vision problems, many of which can impede daily activities such as reading. Therefore, correct diagnosis and treatment of these mTBI-related vision problems is an important part of patient recovery. Numerous eye care providers in the Department of Veterans Affairs, in military settings, and in civilian practices specialize and are proficient in examining patients who have a history of TBI. However, many do not have this level of experience working with and treating patients with mTBI. Recognizing this, we used a modified Delphi method to derive expert opinions from a panel of 16 optometrists concerning visual examination of the patient with mTBI. This process resulted in a clinical tool containing 17 history questions and 7 examination procedures. This tool provides a set of clinical guidelines that can be used as desired by any eye care provider either as a screening tool or adjunct to a full eye examination when seeing a patient with a history of mTBI. The goal of this process was to provide optimal and uniform vision care for the patient with mTBI.

Screening for lifetime concussion in athletes: importance of oculomotor measures

HYPOTHESIS/OBJECTIVE

The purpose of the present study was to determine the utility of oculomotor-based evaluation protocols in screening for lifetime concussion incidence in elite hockey players.

METHODS

Forty-two Division I collegiate male and female hockey players were evaluated using the guidelines of an overall oculomotor-based diagnostic clinical test protocol for the mTBI population. The sensitivity of the collected measures to lifetime concussion was then compared with the corresponding sensitivity of measures of neuropsychological functioning (ImPACT) often used with athletes for acute concussion diagnosis.

RESULTS

This model showed that a hockey player with a Near Point of Fixation Disparity (NPFD) equal to or greater than 15 cm, Visagraph comprehension rate less than 85% and the total score on part A of an ADHD questionnaire equal to or greater than 11 was on average 10.72-times more likely to have previously suffered a concussion than an athlete with lower values on the NPFD and ADHD questionnaire and a higher comprehension rate on the Visagraph. None of the IMPACT baseline assessment measures were significantly predictive of the individual's concussion history.

CONCLUSION

The study provides a relatively sensitive screening tool to assess the probability of previous concussion(s) in an athlete. This model may allow athletic personnel to address in a timely manner the risks associated with repeat concussions and to develop individualized concussion management protocols.

Diagnostic validity of clinical signs associated with a large exophoria at near

Purpose. To analyze the diagnostic validity of accommodative and binocular tests in a sample of patients with a large near exophoria with moderate to severe symptoms. Methods. Two groups of patients between 19 and 35 years were recruited from a university clinic: 33 subjects with large exophoria at near vision and moderate or high visual discomfort and 33 patients with normal heterophoria and low visual discomfort. Visual discomfort was defined using the Conlon survey. A refractive exam and an exhaustive evaluation of accommodation and vergence were assessed. Diagnostic validity by means of receiver operator characteristic (ROC) curves, sensitivity (S), specificity (Sp), and positive and negative likelihood ratios (LR+, LR-) were assessed. This analysis was also carried out considering multiple tests as serial testing strategy. Results. ROC analysis showed the best diagnostic accuracy for receded near point of convergence (NPC) recovery (area = 0.929) and binocular accommodative facility (BAF) (area = 0.886). Using the cut-offs obtained with ROC analysis, the best diagnostic validity was obtained for the combination of NPC recovery and BAF (S  =  0.77, Sp = 1, LR+ = value tending to infinity, LR- = 0.23) and the combination of NPC break and recovery with BAF (S  =  0.73, Sp = 1, LR+ = tending to infinity, LR- = 0.27). Conclusions. NPC and BAF tests were the tests with the best diagnostic accuracy for subjects with large near exophoria and moderate to severe symptoms.

Concurrent vision dysfunctions in convergence insufficiency with traumatic brain injury

PURPOSE

This study assessed the prevalence of convergence insufficiency (CI) with and without simultaneous vision dysfunctions within the traumatic brain injury (TBI) sample population because although CI is commonly reported with TBI, the prevalence of concurrent visual dysfunctions with CI in TBI is unknown.

METHODS

A retrospective analysis of 557 medical records from TBI civilian patients was conducted. Patients were all evaluated by a single optometrist. Visual acuity, oculomotor function, binocular vision function, accommodation, visual fields, ocular health, and vestibular function were assessed. Statistical comparisons between the CI and non-CI, as well as inpatient and outpatient subgroups, were conducted using χ and Z tests.

RESULTS

Approximately 9% of the TBI sample had CI without the following simultaneous diagnoses: saccade or pursuit dysfunction; third, fourth, or sixth cranial nerve palsy; visual field deficit; visual spatial inattention/neglect; vestibular dysfunction; or nystagmus. Photophobia with CI was observed in 16.3% (21 of 130), and vestibular dysfunction with CI was observed in 18.5% (24 of 130) of the CI subgroup. Convergence insufficiency and cranial nerve palsies were common and yielded prevalence rates of 23.3% (130 of 557) and 26.9% (150 of 557), respectively, within the TBI sample. Accommodative dysfunction was common within the nonpresbyopic TBI sample, with a prevalence of 24.4% (76 of 314). Visual field deficits or unilateral visual spatial inattention/neglect was observed within 29.6% (80 of 270) of the TBI inpatient subgroup and was significantly more prevalent compared with that of the outpatient subgroup (p < 0.001). Most TBI patients had visual acuities of 20/60 or better in the TBI sample (85%; 473 of 557).

CONCLUSIONS

Convergence insufficiency without simultaneous visual or vestibular dysfunctions was observed in about 9% of the visually symptomatic TBI civilian population studied. A thorough visual and vestibular examination is recommended for all TBI patients.

A review of convergence insufficiency: what are we really accomplishing with exercises?

INTRODUCTION

Orthoptic exercises have been the primary treatment for convergence insufficiency since this condition's first description in 1855. It is presumed that exercises work by improving fusional convergence. In recent years, research from eye movement laboratories has challenged our theories on the nature and dynamics of convergence, the effect of convergence exercises, and the etiology of primary convergence insufficiency.

METHODS

A review of the ophthalmological, optometric, and basic science literature was done to retrieve the most recent research on vergence eye movements and convergence insufficiency.

RESULTS

Convergence appears to be a bi-phasic response to a change in stimulus position in depth. The first phase, which may represent the contribution of proximal convergence, is not under visual feedback, is fast with a short latency, and is triggered by stimuli moving rapidly in depth or by large, sudden changes in fixation. This phase is followed by a slow vergence movement with a slightly longer latency, triggered by small disparity vergence errors. The second phase is under the control of visual feedback, and represents the contributions of fusional and accommodative convergence. Eye movement recordings indicate that the velocity and amplitude of the first phase of convergence are temporarily adaptable with exercises. The second phase does not appear to be amenable to training. Tonic convergence is also trainable.

CONCLUSION

Convergence exercises are effective in temporarily improving the dynamics of proximal and tonic convergence, but have little effect on fusional or accommodative convergence.

Vision therapy in adults with convergence insufficiency: clinical and functional magnetic resonance imaging measures

PURPOSE

This research quantified clinical measurements and functional neural changes associated with vision therapy in subjects with convergence insufficiency (CI).

METHODS

Convergence and divergence 4° step responses were compared between 13 control adult subjects with normal binocular vision and four CI adult subjects. All CI subjects participated in 18 h of vision therapy. Clinical parameters quantified throughout the therapy included: nearpoint of convergence, recovery point of convergence, positive fusional vergence at near, near dissociated phoria, and eye movements that were quantified using peak velocity. Neural correlates of the CI subjects were quantified with functional magnetic resonance imaging scans comparing random vs. predictable vergence movements using a block design before and after vision therapy. Images were quantified by measuring the spatial extent of activation and the average correlation within five regions of interests (ROI). The ROIs were the dorsolateral prefrontal cortex, a portion of the frontal lobe, part of the parietal lobe, the cerebellum, and the brain stem. All measurements were repeated 4 months to 1 year post-therapy in three of the CI subjects.

RESULTS

Convergence average peak velocities to step stimuli were significantly slower (p = 0.016) in CI subjects compared with controls; however, significant differences in average peak velocities were not observed for divergence step responses (p = 0.30). The investigation of CI subjects participating in vision therapy showed that the nearpoint of convergence, recovery point of convergence, and near dissociated phoria significantly decreased. Furthermore, the positive fusional vergence, average peak velocity from 4° convergence steps, and the amount of functional activity within the frontal areas, cerebellum, and brain stem significantly increased. Several clinical and cortical parameters were significantly correlated.

CONCLUSIONS

Convergence peak velocity was significantly slower in CI subjects compared with controls, which may result in asthenopic complaints reported by the CI subjects. Vision therapy was associated with and may have evoked clinical and cortical activity changes.

Occurrence of oculomotor dysfunctions in acquired brain injury: A retrospective analysis

BACKGROUND

The purpose of this retrospective study was to determine the frequency of occurrence of oculomotor dysfunctions in a sample of ambulatory outpatients who have acquired brain injury (ABI), either traumatic brain injury (TBI) or cerebrovascular accident (CVA), with associated vision symptoms.

METHODS

Medical records of 220 individuals with either TBI (n = 160) or CVA (n = 60) were reviewed retrospectively. This was determined by a computer-based query spanning the years 2000 through 2003, for the frequency of occurrence of oculomotor dysfunctions including accommodation, version, vergence, strabismus, and cranial nerve (CN) palsy.

RESULTS

The majority of individuals with either TBI (90%) or CVA (86.7%) manifested an oculomotor dysfunction. Accommodative and vergence deficits were most common in the TBI subgroup, whereas strabismus and CN palsy were most common in the CVA subgroup. The frequency of occurrence of versional deficits was similar in each diagnostic subgroup.

CONCLUSION

These new findings should alert the clinician to the higher frequency of occurrence of oculomotor dysfunctions in these populations and the associated therapeutic, rehabilitative, and quality-of-life implications.

Intermittent exotropia increasing with near fixation: a "soft" sign of neurological disease

AIM

To examine the association of distance-near disparity with neurological disease in children with intermittent exotropia.

METHODS

A retrospective analysis was performed of the medical records of all children with intermittent exotropia examined at the Arkansas Children's Hospital between 1989 and 2002. The study group consisted of children with intermittent exotropia who had a near deviation that exceeded the deviation at distance by at least 10 prism dioptres. The control group consisted of children with intermittent exotropia who had a distance deviation greater than or equal to the deviation at near. The main outcome measure was the prevalence of neurological abnormalities in the study and control groups.

RESULTS

Among the 29 patients in the study group, 19 (66%) had a history of concurrent neurological abnormalities. Associated neurological conditions included developmental delay (10 patients), attention deficit disorder (four patients), cerebral palsy (four patients), history of intracranial haemorrhage (four patients), periventricular leucomalacia (three patients), seizures (two patients), cortical visual impairment (two patients), hydrocephalus (one patient), history of anoxic brain damage (one patient), history of encephalitis (one patient), and autism (one patient). Among the 37 patients in the control group, seven (19%) had a history of concurrent neurological abnormalities. The difference in the prevalence of neurological disease between the study group and the control group was significant (p=0.0002).

CONCLUSION

Intermittent exotropia increasing with near fixation is associated with neurological disease in children.

Ocular and visual complications of head injury

PURPOSE

To evaluate the pattern of ocular and visual complications of head injury.

METHOD

A prospective study of 225 head-injured patients managed at the University of Ilorin Teaching Hospital, Ilorin, Nigeria. For the purpose of extracting visual complications, a Neurosurgeon and an Ophthalmologist examined each patient and appropriate investigations were carried out. Patients with ocular morbidity were analysed for age, sex, cause of injury, admission Glasgow coma score, and associated injuries in addition to findings at ophthalmic and neurosurgical evaluations.

RESULTS

Two major types of ocular and visual complications were observed in 57 (25.3%) of 225 head-injured patients studied. Soft-tissue injury to the globe and adnexae included periorbital ecchymosis, subconjuctival haemorrhage, lid laceration, or rarely globe rupture in 29 patients. Neuro-ophthalmic ocular cranial nerve palsies occurred in 28 patients, while orbital fracture was encountered in two patients. Ocular injuries were multiple in 60% of cases. The patients, comprising 37 male and 20 female subjects, were aged 9 months to 57 years (mean=28 years). Traffic accident was the leading cause of head injuries (84.2%), while fall from height (7%), assault (7%), and gunshot (1.8%) were miscellaneous causes.

CONCLUSION

Injury to the globe and adnexae and ocular cranial nerve palsies constitute the most common oculovisual complications following head injury in our centre.

Recovery of fusional convergence after systematic practice

Fusional convergence was trained systematically with orthoptic devices in three patients with a severe deficit in convergent fusion resulting from vascular (one case) or traumatic (two cases) brain damage. Within a single-subject baseline design two of the three patients showed a significant, and the third patient a moderate, recovery of fusional range. All patients showed a significant improvement in visual acuity for objects close by, improved reading performance and an increase in stereo acuity (two cases). The results suggest a considerable potential for recovery of oculomotor functions in brain-damaged patients when appropriate treatment methods are applied.

Incidence and treatment of visual dysfunction in traumatic brain injury

The incidence of visual dysfunction and effectiveness of visual exercises in acute traumatically brain injured inpatients in a rehabilitation programme were studied. Vision evaluation norms were established on 23 hospital staff. The evaluation was then administered to 51 inpatients within days after admission. An additional 21 patients were unable to participate, usually due to decreased cognition or agitation. Thirty of 51 (59%) scored impaired in one or more of the following: pursuits, saccades, ocular posturing, stereopsis, extra-ocular movements, and near/far eso-exotropia. For patients having dysfunction in pursuits or saccades, a 2-week baseline was followed by vision exercises. During the baseline interval patients were evaluated by an optometrist to verify therapists' findings. Six patients who participated in several weeks of treatment were evaluated at 2-week intervals by an independent rater. Progress is graphically illustrated. Conclusions were that the suitability of an inpatient vision programme, from our experience, is questionable. However, an initial evaluation proved valuable for informing staff of patients' visual status and for referral to an optometrist/ophthalmologist for further treatment.

Ophthalmic manifestations of head injury

Head injuries are frequently associated with ophthalmic problems. The commonest problems seen in this series of 161 patients with head injury were problems with poor accommodation (16% of patients; 58% of these persisted), convergence (14% of patients; 35% of these persisted), pseudomyopia (19%; 55% persisted) and optic atrophy (26% of the patients; 78% of these were mild and easily missed on routine testing, and 22% were severe). Motility disorders were common, especially cranial nerve palsies. Other less frequent motility disturbances included apparent inferior oblique palsy, comitant esotropia, and exotropia which was often of the convergence insufficiency type.

Time-related sequelae of TBI in patients with prolonged post-comatose unawareness (PC-U) state

Seventy-two patients who were in a post-comatose unawareness state for periods longer than 1 month following traumatic brain injury recovered consciousness thereafter. The incidence of residual sequelae of brain trauma in relation to duration of unawareness was studied. The incidence of motor disability, communication disorders, cognitive disturbances and malbehaviour was studied in the patients recovering consciousness after 1, 2, 3 and 6 months. It was found that no significant differences were found in the incidence of the above-mentioned residual sequelae of brain-damaged patients in relation to duration of post-comatose unawareness. However, 76.1% (51/67) of the patients who recovered consciousness and survived the first year following injury were living at home. Most of these were patients who recovered consciousness within the first 3 months following trauma. None of the patients who were in post-comatose unawareness longer than 6 months did so, Five patients (6.9%) died during the first year. Motor disability, independence in activities of daily living, vocational outcome and place of living were significantly related to duration of prolonged unawareness state whereas the disturbances in high mental functions did not. Although the vocational outcome of patients with post-comatose unawareness is not good, the fact that most of them are still able to live at home, having an acceptable quality of survival, justifies, according to our experience, the comprehensive rehabilitation programme.

Polytrauma associated with traumatic brain injury: incidence, nature and impact on rehabilitation outcome

The rehabilitation outcome of patients with severe traumatic brain injury (TBI) is well documented and is highly correlated to the neurobehavioural sequelae of CNS damage. However, many of these patients suffer from polytrauma involving systems other than the CNS and to systems involved in acquisition of external information. In the present series of 328 patients with severe TBI, 58% had associated trauma, mostly in the skeletal system. The presence of one single associated trauma had no additional effect on rehabilitation as evaluated by actual work placement. In contrast, multiple lesions were liked with a less favourable outcome, probably due to a greater severity of the initial CNS damage. Disturbances in the various information-acquiring systems (e.g. disturbances in eye movements, visual field defects and severe bilateral auditory deficits) were associated with poor outcome. Presence of peri-articular new bone formation and communicating hydrocephalus, usually associated with prolonged periods of unconsciousness, indicated a poor rehabilitation outcome as well.