Vision is among the most complex and extraordinary of the senses, and is made possible by the muscles that control eye movement (Figure 1). These important muscles, known as the extra-ocular muscles, play an essential role in the visual process. Every movement your eyes make, whether looking up, down or side-to-side, is governed by the extra-ocular muscles. They work to direct the eyes in response to signals from the brain, moving the eyes so that they point in the same direction simultaneously. This allows a single image to form clearly in the brain during a process known as fusion.
Any condition which disrupts the eyes’ ability to aim and focus correctly can lead to eye muscle strain, which usually makes its presence known with symptoms of blurred vision, headaches, dizziness and even reading and learning difficulties. While some people who have issues with their eye muscles may only experience one of these symptoms, others are unfortunate enough to suffer the effects of multiple symptoms.
Due to the wide range of symptoms exhibited, it’s not uncommon for patients experiencing them to consult with a variety of different doctors and specialists – though, unfortunately, they often don’t find the relief they’re seeking. This is due in large part to the fact that most people aren’t aware that the visual system can cause the symptoms from which they suffer, and so they don’t think to seek the assistance of a vision specialist. One of the conditions most likely to cause such symptoms is Vertical Heterophoria, a form of Binocular Vision Dysfunction.
Figure 1 Figure 2
Problems Caused by Vertical Heterophoria
With Vertical Heterophoria (VH), the eyes have trouble staying aligned vertically. This condition tends toward creating double vision, which the brain won’t stand for. VH can present itself when the patient’s facial symmetry is slightly misaligned, resulting in one eye being physically higher than the other one (Figure 2). At other times, the eyes can be in perfect alignment but VH symptoms are due to muscle or nerve abnormalities. In certain cases, this condition can also be brought on by neurological disorders, stroke or head trauma. Usually, however, VH is a congenital condition present from birth, and it tends to run in families. In some instances, symptoms don’t start appearing until years down the road, due to the body’s efforts to adapt and counteract the effects of the condition.
The brain cannot tolerate double vision and, in the effort to fuse the two images it receives from the eyes into one, the eye misalignment must be addressed. The brain does this by forcing the muscles to aim one eye a little higher and the other a little lower. With this amount of strain on the eye muscles, in time, they become overworked and tired, sore and stressed, which then brings on the symptoms of VH.
Headaches centered around the temples or in the front of the face are one of the most common symptoms of VH, along with feeling dizzy, disoriented or lightheaded. These sensations occur when the fatigued eye muscles become so tired that they’re no longer able to the hold the two images together into one (fusion). It’s this movement in and out of fusion that can throw you off-balance and bring on feelings of being lightheaded or dizzy.
Additional VH Symptoms
Along with the aforementioned symptoms, sufferers of VH can also experience the following:
- Physical symptoms. Pain with eye movement, pain or aching of the eyes or face (all symptoms similar to migraines, TMJ and sinus issues); upper back and neck pain caused by head tilt (comparable to spinal misalignment problems);
- Vestibular symptoms. Poor depth perception, motion sickness, nausea, balance issues when walking (drifting or unsteadiness), poor coordination (like those experienced by patients with MS, Meniere’s Disease, inner ear disorders or sequela of a stroke);
- Reading difficulties. Problems concentrating (like someone with ADHD might experience), reading and comprehension issues, such as skipping lines when reading, words blurring and running together, losing one’s place when reading (similar to symptoms seen in those with learning disabilities);
- Visual symptoms. Shadowed vision, overlapping vision, blurred or double vision (comparable to symptoms experienced by MS patients); sensitivity to light, problems with reflection or glare;
- Psychological symptoms. Feeling overwhelmed or experiencing anxiety when in big, open buildings with high ceilings and a lot of people, such as a department store or mall (like symptoms often seen in those with agoraphobia or anxiety).
The Solution: Aligning Prism Lenses
To address these debilitating symptoms and help our patients get their lives back, the optometrists at Vision Specialists of Michigan use a unique technique that involves adding prism to your lenses, which adjusts the image that the eye sees up or down, making it much easier for fusion to take place, and taking the strain off the extra-ocular muscles. Once this happens, the blurred vision, headaches and dizziness, and other symptoms markedly improve or disappear as if they were never there.