Binocular vision dysfunctions are a group of visual conditions that affect our lives, some of them are symptomatic and some of them are not. They are conditions in which the two eyes are unable to align properly, which sometimes can lead to double vision or blurry vision. People suffering from these conditions have a small amount of axial misalignment, which are mostly not found on a routine eye exam.
Our eyes are controlled by 6 different muscles and these are innervated by three different cranial nerves. These muscles coordinate the movement of each eye separately. They need to work in harmony to be able to achieve a perfect binocular vision and to avoid double vision. The brain and twelve extra-ocular muscles must work together so that each eye points directly at the observed object. When the eyes cannot perform this eye teaming task accurately, this is therefore referred to as binocular vision dysfunction (BVD).
This condition causes the image not being projected directly in the center of the retina (macula), so the eyes unconsciously use their muscle strength to correct the misalignment. The image is finally projected in the center, but due to the overusing of muscles, a lot of symptoms are reported – not just double vision of blurriness of vision.
Most common and typical vision symptoms are:
- Reading and Learning Disability Symptoms
- Re-reading for comprehension
- Difficulty concentrating
- Skipping the lines when reading
- Losing the words while reading
- Using the finger or a ruler as a guide to follow along on a line or print
- Words sticking together while reading
- Fatigue when reading and being quickly overwhelmed and sleepy
- Double Vision Symptoms
- Blurred vision, overlapping vision, double vision
- Poor depth perception for either far or near
- Kids give expression as they seem to be uncoordinated, especially in sports activities (eg. Catching or hitting balls)
- Poor eye-hand coordination
- Closing one eye makes vision tasks easier
- Headaches and standard vision symptoms
- Eye strain
- Blurry vision at distance and near
- Pain with eye movements (eye muscles)
- Feeling of pressure and heaviness on top of the head or the forehead
- Facial »sinus« pain
- Neck and shoulder discomfort (eg. People try to align the eyes by turning head in one direction)
- Dizziness, nausea and motion sickness symptoms
- Motion sickness and car sickness
- Unsteadiness while driving
- Falls often (more accidents) due to being unsure of their footing
- Drifts to one side while walking
- Avoiding being in the car, ship, train
The severity and number of symptoms vary from one to another. In the development phases of childhood, having a comprehensive eye exam is an essential thing to do. Many times also a small refractive error can bring a misalignment and when corrected the symptoms may disappear. The other option is vision therapy, which is a specially designed training for eyes that improves alignment (also double vision), increases the flexibility of the eyes and makes the symptoms go away.