TBI and Binocular Vision Dysfunction

The effects of TBI can be long-lasting. Patients can suffer from cognitive and motor impairments, chronic headaches, and nausea. Personality changes often accompany cognitive problems, impacting not only the patient but their friends, family, and caretakers. Treatment often involves intensive rehabilitation as considerable effort is required to regain lost motor and cognitive skills. In addition, medical symptoms can persist well after the initial trauma.

Recovering from a TBI relies on the brain’s innate potential to adapt and change. This capacity, known as neuroplasticity, involves the rewiring of neural connections and re-purposing of brain areas in response to brain damage. A patient’s recovery of functionality after motor and mental impairments is dependent on this process. As such, treatment of TBI is a powerful testament to the brain’s ability to persevere through trauma.

Visual deficits are common in patients with TBI. Visual information from the eyes is carried to an inner structure of the brain called the thalamus, from the thalamus to the occipital lobe—the brain’s most posterior section—and subsequently to a variety of cortical targets necessary for the processing of movement and object recognition. Damage to any of these pathways can cause visual problems, and when we consider the broad range of localities that can be affected by blunt force trauma to the head, it’s unsurprising that visual impairments should arise secondary to TBI.

One specific type of damage with broad implications for visual function involves the brain’s projections to the extraocular muscles, the 12 muscles responsible for moving the two eyes around the orbital socket. In extreme cases, damage to the nerves supplying these muscles causes strabismus, a condition where one of the eyes deviates significantly in alignment with the other. This condition can be either chronic or intermittent, and patients will typically present with the complaint of double vision.

These abilities are crucial for tasks which require precise visual functioning, including reading, driving, and moving in visually-cluttered environments. Among those with TBI, difficulty in any of these activities can indicate a dysfunction of binocular vision.

Binocular vision dysfunction (BVD) is a diagnosis which comprises any deficit of the binocular system. Proper visual functioning requires a careful coordination between the movement of both eyes. When the extraocular muscles are not properly coordinated, it becomes difficult to maintain a single image.

In addition to the visual impairments previously described, the strain associated with maintaining binocular vision in the presence of a visual misalignment can cause a variety of medical symptoms. The most common symptoms of BVD include:

A noticeable head tilt is also a well-stereotyped finding of BVD. Some patients will turn their heads to one side in order to compensate for the misalignment between the eyes. This can often cause neck ache, another common symptom of BVD.

The standard treatment for BVD is a pair of realigning glasses which allow the eye muscles to relax. These lenses contain prism, a type of lens which redirects the direction of light entering the eye. Translation of the image in the horizontal or vertical direction provides relief for the eyes, which otherwise strain to project light onto a small area called the fovea, our “island of perfect vision”.

The prism challenge is a process whereby the results of binocular vision testing guide the application of prism in a trial frame while the patient reads text and walks while looking in their field of view. Some patients, especially those suffering from TBI, often report immediate relief of their symptoms once prism lenses are applied. This speaks to the role of proper oculomotor coordination in symptoms as diverse and headaches, dizziness, and nausea.

Patients will often require multiple follow-up visits in order to reassess the strength of correction needed. This is due to a course of progressive relaxation, whereby the muscles accommodate to the prescription and subsequently require a different amount of prism. The right treatment is found, on average, after anywhere between 2–4 visits.

Many of our patients report long-term relief of their symptoms using prism glasses, with a reduction or elimination of their medical symptoms. They also report increased comfort with visually-demanding activities such as reading, driving, and being in open or crowded locations.

In addition to the BVD diagnosis, damage to the inner ear must also be considered as a possible cause of visual disturbances. The vestibular system is important for proper oculomotor functioning, and visual disturbances and/or symptoms of BVD can be precipitated by a dissonance between vestibular and visual inputs to the brain. We suspect that for this reason, noise-cancelling headphones have provided symptom relief for our patients, particularly those who sustained TBI. Hyperacusis secondary to TBI is an open field of inquiry which should be pursued.

Finally, tinted lenses can provide relief for TBI patients who suffer from light sensitivity secondary to their injury. Blutech is a yellow tint which blocks artificial blue light, whereas whereas FL41 is a pink tint which provides considerable relief from fluorescent lighting — a common complaint of TBI patients.

These 3 therapeutic measures — prism lenses, sound cancelling headphones, and tints — have been called the ‘trifecta’. Many of our TBI patients are highly responsive to these treatments, and report symptom relief of their headaches, dizziness, and nausea after utilizing these tools.

TBI is a serious condition which affects many Americans. In addition to cognitive and motor impairments, patients who suffer from TBI can develop visual impairments and medical symptoms related to a dysfunction of their binocular vision. Binocular Vision Dysfunction is an emerging diagnosis which reflects the onset of headaches, dizziness, nausea, and difficulty reading secondary to visual misalignments of the extraocular muscles. TBI patients should be screened using a comprehensive neurovisual examination which tests the eye’s ability to work together.

Related posts:

Depression comes in many different forms, and it can happen to anyone of any age. Depression can also come from many different reasons. It could be because of a death of a loved one, feeling like you…

As a budding Data Scientist and data nerd, things like the sub-Reddit “Data Is Beautiful” tend to bring joy to my morning. I especially like the visualizations that are animated. I find them…

hey so uhm if you want you should microwave your glazed donuts because it tastes dope as peepee. “tip” is published by ✄.