Neuro-Ophthalmic Care for War Veterans and Military Members: Unique Considerations, Challenges, Management Strategies, and Recommendations

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Article initiated by:

Bohan Kim, Osama Al Deyabat, MBBS

All contributors:

Andrew Go Lee, MD, Bohan Kim, Christopher M. Anthony, Nagham Al-Zubidi, MD, Saif Aldeen Alryalat, MD, Nagham Al-Zubidi, MD, Osama Al Deyabat, MBBS

Assigned editor:

Osama Al Deyabat, MBBS

Review:

Assigned status Up to Date

 by Osama Al Deyabat, MBBS on April 11, 2024.

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Overview

Military personnel and combat veterans are exposed to various environmental hazards and traumatic events during their service that necessitate neuro-ophthalmic care. With the increased prevalence of improvised explosive devices (IED), blast trauma, and survival of combat injuries in modern warfare, severe ocular injuries have increased. The most exhaustive investigation to date regarding the prevalence of eye conditions among war veterans is a retrospective case series encompassing 890 eye injuries suffered by 652 patients admitted to Walter Reed Army Medical Center (WRAMC) between 2001 and 2011, following combat engagements in Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF). Among the cases examined, 193 instances of neuro-ophthalmic involvement were identified, accounting for 21.69% of the cohort. This article comprehensively explores the prevalence, diagnostic work-up, management strategies, and long-term care considerations specifically tailored to meet the needs of military members and veterans with neuro-ophthalmic conditions, aiming to furnish neuro-ophthalmologists involved in the care of military personnel and veterans with comprehensive guidance.

Neuro-Ophthalmic Conditions in the Veteran Population

Traumatic Brain Injury

In the aforementioned study, traumatic brain injury (TBI) accounted for 40.31% of all reported cases of ocular trauma. TBI encompasses a spectrum of head injuries resulting from blunt or penetrating trauma, with varying degrees of severity. TBI usually occurs due to acceleration-deceleration injury. When the cranial vault is subjected to an outside force inducing abrupt changes in velocity, the brain moves internally and impacts the cranial walls. This can lead to injuries ranging from mild (concussion) to severe (diffuse axonal injury). Neuroimaging may confirm extra-axial (e.g. epidural hematoma, subarachnoid hemorrhage), intra-axial (e.g., parenchymal bleed), focal or diffuse intracranial pathology including diffuse axonal injury but often the neuroimaging studies are nonspecific or even normal in TBI.

The neuro-ophthalmic manifestations of TBI depend on these structural factors as well as the specific areas of the brain that are injured. TBI can affect both the optic nerve and the anterior visual pathway, the optic chiasm and optic tracts, radiations, and the visual cortex. TBI can lead to a range of ocular manifestations, including loss of visual acuity, color vision, depth perception, visual field, pupillary function, accommodation, or eye movement. Nonspecific blurred vision, headache, eye pain, and photophobia are also common complaints in TBI.

Traumatic Optic Neuropathy

Direct optic nerve injury was observed in 8.88% of all cases and 44.38% of all neuro-ophthalmic injuries. Optic nerve avulsion was observed in 1.46% of cases and 7.3% of neuro-ophthalmic injuries. Combat-related trauma can result in traumatic optic neuropathy (TON), which poses a significant potential threat to vision. TON presents in two main forms: direct and indirect TON. The direct form of TON often arises when the optic nerve sustains trauma from bone fragments or experiences anatomical disruption due to contusion, concussion, avulsion, or transection. Conversely, indirect TON typically arises from blunt trauma to the head or eye, transmitting stress through the surrounding soft tissues and skeletal structures to the optic nerve (often in the optic canal). Such trauma compromises the optic nerve's integrity, resulting in varying degrees of vision loss. Direct TON often results in severe visual impairment and typically carries a worse prognosis compared to indirect TON.

Blast-induced Traumatic Optic Neuropathy

Blast-induced Traumatic Optic Neuropathy (BON) is a unique form of indirect traumatic optic neuropathy (TON) caused by exposure to blast overpressure. Unlike typical TON cases involving penetrating damage or significant blunt trauma, BON stands out for its lack of such physical injury. Instead, the optic nerve sustains damage from the shockwave produced during the blast, despite not directly encountering physical harm.

Orbital Compartment Syndrome

There were thirty-six cases of lateral canthotomy performed out of a total of 890 eyes (4.04%) because of presumable orbital compartment syndrome (OCS). OCS is a vision-threatening elevation of intra-orbital pressure that exceeds the vascular perfusion pressure of the ophthalmic artery. OCS most commonly occurs during the acute sequelae of orbital or facial trauma. In this scenario, trauma may result in diffuse soft tissue swelling, as well as retrobulbar and orbital hemorrhage, all of which can increase intra-orbital pressure because of the inflexibility of the surrounding bony orbital walls and orbital septum.

Orbital Apex Syndrome

Orbital fractures were commonly observed in the study population, comprising 33.03% of cases. Penetrating and nonpenetrating orbital apex injuries including optic canal or orbital fracture can result in dysfunction of the optic nerve (II) or ocular motor cranial nerves (e.g., oculomotor nerve (III), trochlear nerve (IV), abducens nerve (VI)) and/or the ophthalmic branch of the trigeminal nerve (V). Cranial nerve injuries among all ocular traumas have been noted at 6% and comprised 38% of neuro-ophthalmic injuries and signs.

Toxic/Nutritional Optic Neuropathy

Veterans may face increased risks of toxic or nutritional optic neuropathies due to environmental exposures or dietary deficiencies (e.g., prisoner of war) encountered during military service (e.g., combat exposure to toxic weapons). Toxic optic neuropathies can arise from exposure to medications, chemicals, environmental toxins, or recreational drugs, leading to acute or chronic visual loss. Prompt identification and cessation of offending agents are crucial in managing these conditions.

Vitamin (such as B1, B6, B12) deficiencies can occur, particularly in cases of poor nutrition (e.g., prisoner of war) or from alcohol use disorder. Since these vitamins are vital for maintaining nervous system health, including the optic nerve, nutritional optic neuropathies can manifest with bilateral central visual loss.

Tobacco optic neuropathy (TON), previously termed "tobacco–alcohol amblyopia," is another type of toxic optic neuropathy often associated with individuals who smoke pipes or cigars. This disorder typically presents with painless, slowly progressive, and bilateral dyschromatopsia along with visual loss, requiring nutritional supplementation and lifestyle modifications to prevent further visual deterioration.

Post-Traumatic Stress Disorder

PTSD, which is a prevalent condition among veterans, does not appear to directly cause visual dysfunction, but it is closely associated with TBI, which has a known visual impact. Nonetheless, patients with PTSD tend to have higher self-reported visual dysfunction when compared to a statistically similar cohort without PTSD. Thus, the psycho-social aspect of veteran care is an important consideration for ruling out structural dysfunction. Functional visual disorder (FVD) can occur in the setting of PTSD or other diagnostic and statistical manual (DSM) V diagnoses.

Diagnosis

Comprehensive history-taking and physical examination are essential components of the assessment of military members and combat veterans presenting with neuro-ophthalmic complaints. Understanding the patient's medical history, including any military service-related injuries or exposures, is crucial for identifying potential risk factors and guiding diagnostic evaluation and management. Similarly, a thorough physical examination, including neuro-ophthalmic assessments and specialized diagnostic tests, allows for the detection of subtle signs and symptoms indicative of underlying neuro-ophthalmic pathology. By utilizing standard modalities in the assessment and diagnosis of neuro-ophthalmic conditions, neuro-ophthalmologists can obtain comprehensive insights into the underlying pathology, guide appropriate management strategies, and optimize visual outcomes for military members and combat veterans.

History

Military Service History: Inquire about the patient's military service history, including deployments, combat exposure, blast injuries, prisoner of war status, or traumatic events, which may be relevant to the development of neuro-ophthalmic conditions such as traumatic brain injury (TBI) or optic nerve trauma. In the Jaksha study examining neuro-ophthalmic injuries among veterans from Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF), findings revealed that 52.25% were attributed to improvised explosive devices (IEDs). It's crucial to highlight that as many as 19% of patients were found to be non-compliant with the use of eye protection. Therefore, it's advisable to include inquiries about the status of eye protection when assessing patients.

Symptomatology: Ascertain the nature, onset, duration, and progression of neuro-ophthalmic symptoms, including visual disturbances, diplopia, headaches, photophobia, or changes in visual field perception, which may suggest specific underlying etiologies.

Medical History: Obtain a comprehensive medical history, including past ocular surgeries, ocular diseases, systemic conditions, or medication use, which may contribute to or exacerbate neuro-ophthalmic symptoms.

Psychosocial History: Assess for psychosocial factors, including history of post-traumatic stress disorder (PTSD), depression, anxiety, or substance abuse, which may impact the patient's perception of visual symptoms and overall well-being.

Comprehensive Neuro-Ophthalmic Evaluation

Military-Specific Vision Screening: Vision experts at the VA published mTBI vision screening guidelines for eye care providers to use as an adjunct to a conventional eye exam. The guidelines identify the following exams as being important for every TBI patient: distance cover test, near cover test, versions (extraocular motility) and pursuit, accommodation, saccades, near point of convergence, and repeated near point of convergence. In addition, the guidelines present a list of questions to ask the patient; they are designed to elicit information in six categories related to the history of the TBI event, sensory effects, eye injury/pain, vision, and reading.

Visual Acuity Assessment: Visual acuity testing is essential for evaluating the clarity of vision and detecting any refractive errors or visual impairments. A large sample of military personnel was studied with combat injuries comprising 68 inpatients with moderate to severe TBI, all in rehabilitation, and 124 outpatients with mild TBI. The majority (78–98 percent) had a VA of 6/18 or better. However, inpatients and outpatients experienced VA loss ranging from 6/30 to no light perception in 13 percent and 1.6 percent of individuals, respectively.

Visual Field Testing: Visual field examinations, such as Humphrey or Goldmann perimetry, play a critical role in evaluating both the peripheral and central visual fields. Numerous studies have highlighted the presence of visual field issues TBI cases. Given the diffuse and unpredictable nature of TBIs, visual field testing becomes particularly valuable for potentially pinpointing the location of lesions along the visual pathway.

Pupillary Examination: Pupillary evaluations provide valuable information about optic nerve function and integrity of the autonomic nervous system. The prevalence of afferent pupillary defect was notably high, constituting 42.7% of reported neuro-ophthalmologic findings among veterans engaged in Operations Iraqi Freedom (OIF) and Enduring Freedom (OEF), as noted by Jaksha. TON typically presents with RAPD. In addition, pupillary response in the acute stage of a TBI can be used to indicate treatment options, infra-red pupillometry providing a scalar value to the pupillary function, namely the neurological pupil index (NPi).

Ocular Motility Assessment: Assessing ocular alignment, versions, and ductions helps in evaluating extraocular muscle function and detecting any abnormalities indicative of cranial nerve palsies or oculomotor dysfunction.

Fundoscopic Examination: Fundoscopic examination allows for a detailed assessment of the optic nerve head, retina, and vasculature. It helps in identifying signs of optic nerve pathology, retinal abnormalities, or vascular changes suggestive of systemic diseases, such as diabetic retinopathy, hypertensive retinopathy, or vascular occlusive disorders.

Diagnostic Modalities

Neuroimaging (MRI, CT): Neuroimaging techniques like magnetic resonance imaging (MRI) or computed tomography (CT) are crucial for identifying intracranial lesions, structural irregularities, or traumatic injuries that impact the visual pathways and brain tissue. These modalities are especially valuable for determining whether urgent surgical intervention is necessary by either confirming or excluding the presence of such conditions.

Optical Coherence Tomography (OCT): OCT imaging enables the non-invasive assessment of the structure and thickness of the retinal nerve fiber layer and optic nerve head. It aids in the diagnosis and monitoring of optic neuropathies. Also, recent research found that veterans with TBI had a higher rate of retinal thinning than did a control group.

Visual Evoked Potentials (VEPs): VEP testing evaluates the functional integrity of the visual pathways from the retina to the visual cortex. The peak time and amplitude of the waveforms denote the function of the optic nerve anterior to the optic chiasm. It is especially helpful in prognosticating patients with already poor vision. Also, in patients with a history of head trauma but no significant clinical and neuroimaging findings, VEP was able to detect significant differences in VEP amplitude and implicit time.

Management

Accurate diagnosis is pivotal in managing neuro-ophthalmic conditions in military members and veterans, as it tailors treatment strategies to the underlying pathology. A precise diagnostic approach ensures effective management, optimizing visual function while minimizing complications. Importantly, management strategies vary significantly depending on the specific diagnosis, highlighting the need for individualized approaches. By considering disease severity, functional impairment, and treatment goals, neuro-ophthalmologists can customize care plans to address the unique needs of each patient.

Certain conditions require rapid, algorithmic clinical diagnosis and time-sensitive management. Orbital compartment syndrome, akin to other compartment syndromes, poses a significant risk of morbidity and demands immediate intervention, such as lateral canthotomy. Failure to promptly address OCS can rapidly impair vision due to ischemia of the optic nerve and retina.

Treatment of traumatic optic neuropathy (TON) lacks a standardized approved therapy. Instead, observation of injury progression is advised. Current treatment options include high-dose steroid courses, surgical decompression to alleviate optic nerve pressure, and a combination of steroids and surgery. However, the use of high-dose corticosteroids is contentious due to the potential increased risk of death post-head injury. Some argue against any treatment, as it may prove ineffective or exacerbate the condition. Additionally, recovery prospects from this type of optic neuropathy seem more favorable compared to direct TON.

In managing traumatic brain injury (TBI), prompt and appropriate care can lead to recovery within three months for many patients with mild TBI. Acute management involves first identifying any intracranial injuries requiring urgent surgical intervention before assessing for potential TBI and directing the individual toward suitable care. Evaluation approaches in military settings vary by country, with some relying on symptom assessment while others mandate medical evaluations following events that could lead to TBI. Early detection and intervention are emphasized across the board to mitigate symptoms and prevent worsening outcomes. However, this can be challenging in military settings due to barriers to seeking help. Neurocognitive testing and clinical examinations, such as the Rivermead Post Concussion Symptoms Questionnaire or the Military Acute Concussion Evaluation (MACE), are utilized to monitor TBI progression and determine readiness to return to duty.

For TBI-related visual problems, specific treatment guidelines are lacking. Management relies on existing treatments tailored to the displayed symptoms. For instance, photophobia may be addressed with light-filtering lenses, while visual acuity deficits may benefit from spectacles with specialized tints and prisms.

Multidisciplinary Approach to Care:

Screening by Primary Care: Defense Centers of Excellence within the Military Health System have devised recommendations for mTBI vision screening, drawing from expert opinions across Air Force, Army, Marine Corps, and Navy representatives. These recommendations, accompanied by an assessment algorithm, serve as a guide for primary care physicians both in combat zones and elsewhere. The algorithm aids in distinguishing urgent referrals for eye problems (red flags) from common visual symptoms post-concussion (yellow flags). It includes procedural advice for screening and referral processes, facilitating decisions regarding referrals to various specialties such as ophthalmology, neuro-ophthalmology, optometry, neurology, or maxillofacial surgery.

Collaboration with Neurologists, Neurosurgeons, and Other Specialists: Engaging in interdisciplinary collaboration with neurologists, neurosurgeons, and other medical specialists to facilitate comprehensive evaluation, diagnosis, and management of complex neuro-ophthalmic conditions. Certain manifestations of TON can benefit from emergent surgical optical canal decompressions done by neurosurgeons.

Rehabilitation Services for Patients with TBI and Visual Impairment: Providing access to rehabilitation services, including vision therapy, occupational therapy, and physical therapy, to support military members and veterans with traumatic brain injury (TBI) and visual impairment in achieving optimal functional outcomes and maximizing quality of life.

Psychosocial Support for Patients with PTSD and Associated Neuro-Ophthalmic Symptoms: Offering psychosocial support services, including counseling, psychotherapy, and support groups, to address the psychological and emotional needs of military members and combat veterans with post-traumatic stress disorder (PTSD) and associated neuro-ophthalmic symptoms, promoting holistic well-being and recovery.

Tele-Ophthalmology: Neuro-ophthalmologists have an opportunity to enhance the care of veterans by embracing teleophthalmology services. A remarkable advancement in this realm is the development of the Forward Operating Base Expert Telemedicine Resource Utilizing Mobile Application for Trauma (FOXTROT), a mobile phone application approved by the U.S. Military. FOXTROT represents a pioneering effort in bringing teleophthalmology to combat zones, specifically designed to elevate and broaden ophthalmic care in deployed settings like Afghanistan. This innovative tool operates through a secure server known as the Mobile Health Care Environment, ensuring the confidentiality and reliability of patient data.

By incorporating these recommended exams, diagnostic modalities, and multidisciplinary approaches into the care of military members and combat veterans, healthcare providers can effectively evaluate and manage neuro-ophthalmic conditions, optimize visual outcomes, and enhance the overall quality of life for those who have served their country.