Binocular Vision Disorder
Binocular vision disorders are conditions where the eyes are unable to align properly. This causes overcorrection or overcompensation for the misalignment, creating strain on the muscles in the eye because he or she is constantly trying to re-align the eyes to eliminate blurriness and double-vision.
Symptoms may include:
- Dizziness, headaches and nausea
- Unsteadiness while walking
- Anxiety as a result of difficulty driving or reading
- Anxiety as a result of too much stimuli in a large space or large group of people
- Trouble concentrating while reading
- Trouble with reading comprehension
- Fatigue while reading
- Restless sleep
- Poor eye contact
- Avoidance of work
- Double vision
Often symptoms of ADD and ADHD appear similar to those of Binocular Vision Dysfunction.
Convergence insufficiency is a common binocular disorder in which a person’s eyes don’t work cohesively at close distances. It is an eye-teaming problem where eyes drift apart or cross during reading and other close activities.
The tough thing about convergence insufficiency is that it often goes undiagnosed because a person can pass a typical 20/20 eye chart test and still have it. We recommend getting your child an eye exam before they are 6 years old. A simple school exam isn’t in-depth enough to diagnose convergence insufficiency; a comprehensive eye exam is necessary.
Many people that have convergence insufficiency won’t complain of symptoms because the brain will ignore the input of one eye to avoid the double vision. This vision suppression causes the loss of binocular vision and depth of perception. This has a negative impact on coordination, sports, distance judgement, eye contact and motion sickness.
Amblyopia is an eye disorder that occurs when the brain and the eyes do not work together properly and the brain favors one eye over the other. It can result from any condition that prevents one eye from focusing less than the other or when there is vision loss in one eye, even with the best correction. When one eye fails to achieve normal vision the brain begins to ignore the input from that eye and the result can be amblyopia or “lazy eye”.
Problems often begin in infancy and early childhood. If it is diagnosed early enough, treatment can begin and reduced vision can be avoided. If left untreated, amblyopia can cause severe visual disability and in some cases legal blindness.
There are three different kinds of amblyopia:
Strabismic Amblyopia is when one eye is misaligned, it doesn’t focus straight and looks either up, down or out. The brain then will ignore the input from this eye and vision will begin to deplete. Of course, with all eye disorders, an exam is needed for accurate diagnosis, however there is a simple test you might try at home. A sign that strabismic amblyopia may be present is that your child cries or whines when one or the other eye is covered during visual activities. This can be a sign of discomfort and confusion that is caused by the brain favoring one eye and ignoring the other.
Refractive Amblyopia is when there are unequal refractive errors in the eyes. This is when there is a significant difference in unmatched near or farsightedness. Again, the brain will rely more heavily on the eye that is less uncorrected and ignore the input from the worse eye.
Deprivation Amblyopia is when there is something blocking the light from entering the eye, most likely a cataract. The brain gets almost no input or very blurry input from the cataract eye and, once again, will begin to ignore the information supplied.
Strabismus – Exotropia/Esotropia and Double Vision
Strabismus is a binocular vision disorder in which the eyes don’t work together correctly. A person with strabismus will have eyes that don’t align and you will see the person’s eye turn in, out, up or down independently from the other one. You may see this happening all the time or intermittently.
Strabismus can cause amblyopia. When the eyes don’t work together, and one points in a different direction, the brain receives 2 different visual images. The brain may ignore the image from the misaligned eye to avoid double vision, this results in underdeveloped vision which in turn can cause serious reading and learning problems later in life.
There are two different kinds of strabismus:
Esotropia – in which one or both eyes turns inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a “cross-eyed” appearance.
Exotropia – in which one or both of the eyes turn outward. It is the opposite of crossed eyes.
Another symptom of strabismus is double vision. When the eyes don’t orient the same direction and receive two sets of information you might see double or “ghost” images. When your eyes point in two directions either your brain receives two sets of input or it shuts one eye off and only takes in input from one eye. Double vision occurs when your brain continues to get input from both eyes.
Strabismus can be present in very young children and babies as a result of their new and developing visual systems. It is influenced by genetics, so if you have a family history of strabismus, your child is more likely to develop it. It can be detected in any well-baby check up but all children should also have a formal vision screening in the preschool years.
Strabismus, when detected early, can be treated and no long term effects are necessary.