Chronic visual dysfunction after blast-induced mild traumatic brain injury

Magone, M. Teresa; Kwon, Ellen; Shin, Soo Young

doi:10.1682/jrrd.2013.01.0008

Cited by 69 publications

(74 citation statements)

References 37 publications

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“…The acute and chronic visual problems experienced by servicemembers and Veterans following blast exposure are frequent and often complex [6][7][8]10,[29][30]. While exposure to low-level blast was not expected to induce an mTBI, we hypothesized that the cumulative effects of repetitive low-level blasts could produce damage to ocular structures and parts of the brain responsible for ocular motility and visual processing, which could induce mTBI-like symptoms.…”

Section: Discussionmentioning

confidence: 99%

Effects of repetitive low-level blast exposure on visual system and ocular structures

et al. 2015

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Abstract-The purpose of this study was to determine whether repetitive exposure to low-level blasts during military breacher training produces acute and cumulative damage to the ocular tissues or visual system. The effects of low-level blast exposure on high-contrast visual acuity, contrast sensitivity, oculomotor function, color vision, visual field (VF), pupillary light reflex, corneal endothelial cell density (ECD), macular thickness, retinal nerve fiber layer thickness, and cup-to-disc ratio were assessed using a battery of standard clinical ophthalmic tests administered 10 times over a 2-year period. Data from nine male breacher instructors (Cadre) were compared with data from four male breacher engineers (Control). The Cadre group showed higher vertical deviation at near than the Control group over time. The VF mean deviation on the left eye tended to be worse in the Cadre group throughout the study, suggesting a decrease in VF sensitivity (Cadre: -0.20 +/-0.15 dB; Control: 1.05 +/-0.15 dB; p = 0.03). , p = 0.03). These results suggest that even low-level primary blast has the potential to produce occult eye injury.

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Section: Discussionmentioning

confidence: 99%

Effects of repetitive low-level blast exposure on visual system and ocular structures

et al. 2015

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“…26 Magone found a much lower rate of convergence and accommodative insufficiency 50 months after blast-induced mild TBI, which indicates possible improvement with time. 27 However, the reported rate of 25 % for accommodative and convergence insufficiency remains at a 2.5-fold higher rate compared to mild TBI without a blast mechanism. 27,28 Convergence insufficiency is common after TBI and is characterized by exophoria at near fixation, more than distance, and an abnormal near point of convergence.…”

Section: Binocular Vision Dysfunction After Blast-induced Mild Traumamentioning

confidence: 98%

“…27 However, the reported rate of 25 % for accommodative and convergence insufficiency remains at a 2.5-fold higher rate compared to mild TBI without a blast mechanism. 27,28 Convergence insufficiency is common after TBI and is characterized by exophoria at near fixation, more than distance, and an abnormal near point of convergence. 8,28 The rate of convergence insufficiency has been reported to be about 3-5 % in the general population and 9 % in civilian patients after TBI.…”

Section: Binocular Vision Dysfunction After Blast-induced Mild Traumamentioning

confidence: 98%

“…8,28 The rate of convergence insufficiency has been reported to be about 3-5 % in the general population and 9 % in civilian patients after TBI. 27,29 In patients after blast-induced mild TBI it ranges between twenty-five to forty-seven percent. 26,27,[30][31][32] (see Table 1).…”

Section: Binocular Vision Dysfunction After Blast-induced Mild Traumamentioning

confidence: 99%

“…27,29 In patients after blast-induced mild TBI it ranges between twenty-five to forty-seven percent. 26,27,[30][31][32] (see Table 1). Similarly, accommodative insufficiency ranged between 23-46 % in the previously mentioned studies.…”

Section: Binocular Vision Dysfunction After Blast-induced Mild Traumamentioning

confidence: 99%

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Visual Dysfunction in Combat-related Mild Traumatic Brain Injury—A Review

Magone¹,

Cockerham²,

Shin³

2013

US Neurology

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Approximately half of all military personnel who have served in the conflicts in Iraq and Afghanistan are reported to have some degree of combat-related mild traumatic brain injury (TBI). Although in civilian concussion injuries symptoms typically resolve within several weeks, blast-induced mild TBI may be accompanied by prolonged symptoms and afferent and efferent visual dysfunction. Most commonly near vision problems and photophobia are the presenting symptoms. A complete eye exam including vision testing, oculomotor function, and near tasking, is highly recommended after blast-induced mild TBI to detect and improve symptoms in this young patient population. A review of the current literature is presented. KeywordsMild TBI, visual dysfunction, combat-related injuries, TBI Disclosure: The authors have no conflicts of interest to declare. Blast Injury MechanismsThere are several factors that can affect the degree of brain injury. At the time of the explosion a shock front is created followed by a blast wave, which expands until the pressure falls below atmospheric pressure. 16,17 Initially, the primary blast wave passes through body armor and bone, and is able to disrupt underlying tissues through embedded shear and stress waves. 13,22 Organ systems with high air content such as the pulmonary, gastrointestinal and auditory systems are the most susceptible, but overpressure also causes damage to the central nervous system, visual system, musculoskeletal and cardiovascular systems. 23 Secondary damage occurs when debris or fragmentation from the explosive device or surrounding objects penetrate the body. 24 Tertiary blast injury involves acceleration and deceleration forces, such as occur when a body is propelled and crashes into a fixed structure or the ground. 15 Quaternary injury occurs

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Primary Visual Pathway Changes in Individuals With Chronic Mild Traumatic Brain Injury

Rasdall,

Cho,

Stahl

et al. 2024

JAMA Ophthalmol

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ImportanceIndividuals with mild traumatic brain injury (TBI) often report vision problems despite having normal visual acuity and fundus examinations. Diagnostics are needed for these patients.ObjectiveTo determine if a battery of assessments or machine-learning approaches can aid in diagnosing visual dysfunction in patients with mild TBI.Design, Setting, and ParticipantsThis prospective, observational, case-control study was conducted between May 2018 and November 2021. The study setting was at a level 1 trauma research hospital. Participant eligibility included adult males and females with recorded best-corrected visual acuity and normal fundus examination. Individuals in the case group had a history of mild TBI; controls had no history of TBI. Exclusion criteria included a history of ocular, neurological, or psychiatric disease, moderate-severe TBI, recent TBI, metal implants, age younger than 18 years, and pregnancy. Cases and controls were sex- and age-matched. Data analysis was performed from July 2023 to March 2024.ExposuresHistory of mild TBI in the case group.Main Outcomes and MeasuresThe single-session visit included the Neurobehavioral Symptom Inventory and measurements of oculomotor function, optical coherence tomography, contrast sensitivity, visual evoked potentials, visual field testing, and magnetic resonance imaging.ResultsA total of 28 participants (mean [SD] age, 35.0 [12.8] years; 15 male [53.6%]) with mild TBI and 28 controls (mean [SD] age, 35.8 [8.5] years; 19 female [67.9%]) were analyzed. Participants with mild TBI showed reduced prism convergence test breakpoint (−8.38; 95% CI, −14.14 to −2.62; P = .008) and recovery point (−8.44; 95% CI, −13.82 to −3.06; P = .004). Participants with mild TBI also had decreased contrast sensitivity (−0.07; 95% CI, −0.13 to −0.01; P = .04) and increased visual evoked potential binocular summation index (0.32; 95% CI, 0.02-0.63; P = .02). A subset of participants exhibited reduced peripapillary retinal nerve fiber layer thickness, increased optic nerve/sheath size, and brain cortical volumes. Machine learning identified subtle differences across the primary visual pathway, including the optic radiations and occipital lobe regions, independent of visual symptoms.Conclusions and RelevanceResults of this case-control study suggest that the visual system was affected in individuals with mild TBI, even in those who did not self-report vision problems. These findings support the utility of a battery of assessments or machine-learning approaches to accurately diagnose this population.

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Chronic visual dysfunction after blast-induced mild traumatic brain injury

Cited by 69 publications

References 37 publications

Effects of repetitive low-level blast exposure on visual system and ocular structures

Effects of repetitive low-level blast exposure on visual system and ocular structures

Visual Dysfunction in Combat-related Mild Traumatic Brain Injury—A Review

Primary Visual Pathway Changes in Individuals With Chronic Mild Traumatic Brain Injury

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