(Relationship of TBI to Vertical Heterophoria, a newly described syndrome)

Traumatic Brain Injury (TBI) is a condition that afflicts thousands of people in the United States. There are a number of different symptoms and problems that are caused by TBI. Two of the more common symptoms are dizziness and headaches. TBI patients are frequently quite bothered by these symptoms, which precipitates extensive testing and evaluation in an attempt to find an effective treatment. These evaluations included multiple consultations (including neurology, ENT/ otology / vestibular specialists, PM & R, chiropractor, psychiatrist) and multiple tests (including CT, MRI, ENG / vestibular testing). They have tried multiple medications and therapies, but in many instances, have experienced minimal to no relief of their symptoms. It now appears that an uncommonly recognized binocular vision condition – Vertical Heterophoria – is responsible for a large number of these patients’ symptoms of dizziness and headache.

Vertical Heterophoria is a condition where the two eyes have difficulty keeping in vertical alignment. This can lead to double vision, which the brain does not tolerate. Sometimes one eye is physically higher than the other (figure 1). Sometimes the eyes are aligned correctly but muscle or nerve abnormalities cause the problem. This condition is known to be precipitated by head trauma.

In order for the brain to create one image from the two eyes (fusion) and avoid double vision, the brain forces the eyes to look at the exact same spot. To accomplish this, the eye muscles will strain to make one eye look up a little more, and the other eye to look down a little more. Over a long period of time, the stress and strain on the visual system precipitate the symptoms of Vertical Heterophoria (VH). These include headaches, usually in the front of the face or in the temples. VH can also cause a feeling of being disoriented, lightheaded or dizzy. As the muscles strain, they become fatigued, causing the image seen by one eye to not continuously overlap the image seen by the other eye. In other words, fusion is no longer continuously maintained. This moving in and out of fusion creates the feeling of dizziness, lightheadedness and a sense of imbalance. Those who suffer from Vertical Heterophoria may also have other symptoms in addition to those of headaches and dizziness:

• additional pain symptoms such as face ache, eye pain or pain with eye movement (symptoms similar to sinus problems, migraines, TMJ problems); neck ache and upper back pain due to a head tilt (similar to spinal misalignment symptoms);
• additional vestibular symptoms such as motion sickness, nausea, poor depth perception, unsteadiness while walking or drifting to one side while walking (“I’ve always been clumsy”), lack of coordination (symptoms are similar to those seen in patients with MS, sequelae of a stroke, an inner ear disorder or Meniere’s Disease);
• reading symptoms such as difficulty with concentration (symptoms are similar to those experienced with ADHD), difficulty with reading and comprehension, skipping lines while reading, losing one’s place while reading, words running together while reading (symptoms similar to those seen in someone with a learning disability);
• vision symptoms such as blurred vision, double or overlapping vision, shadowed vision (symptoms similar to those seen in patients with MS); light sensitivity, difficulty with glare or reflection;
• psychological symptoms such as feeling overwhelmed or anxious when in large contained spaces like malls or big box stores, feeling overwhelmed or anxious in crowds (symptoms similar to those seen in patients with anxiety or agoraphobia).

To correct this problem, the optometrist will add prism to your glasses. Prism is a way of making the glasses such that the image seen by the eye is moved up or down – whatever is needed to allow for fusion to occur without straining the extraocular muscles. Once this occurs, the headaches, dizziness, blurred vision and other symptoms resolve.

Figure 1