Binocular Diplopia Causes

Binocular diplopia is double vision. When a person experiences double vision it means that the visual information that the right eye sends to the retina is not being combined, or fused, adequately with the visual information that the left eye contributes. There are many reasons for someone to have diplopia, including poor control of the eye muscles, convergence insufficiency, convergence excess and an assortment of diseases. Some diplopia can be resolved by a program of in-office optometric vision therapy under the supervision of a developmental optometrist who specializes in binocular vision disorders.

Identification

• Binocular diplopia happens when the eyes don't team together accurately to point to the same location in space at the same exact time. Binocular vision is a bit like when two children play a three-legged race. Both of the partners have to adjust and match the other person's gait and timing. Otherwise, they won't be efficient in the race. Both partners might be highly skilled runners when they are alone, but if they don't coordinate together they could be beaten by a pair of very slow but cooperative partners. When an individual's eyes do not team well together he may either experience diplopia--double vision--or he may tend to suppress the information from one of the eyes and develop amblyopia--a lazy eye--without even being aware of it.

Strabismus

• People who have strabismus may experience binocular diplopia. A strabismus is an eye turn that prevents both eyes from pointing to the same visual target. There are quite a few varieties of a strabismus. Some people have an eye that turns in toward the nose, an esotropia. Other people have an eye that turns out toward the ear, an exotropia. The eye turn may be more pronounced when the person is fatigued or stressed. It may be limited to one eye or it could intermittently affect both eyes. Still other people have an esophoria or an exophoria in one eye. This means that one eye stays in a position relative to the other eye that points too far in (esophoria) or too far out (exophoria). As long as the person who has an eye turn does not suppress the information received by either one of their eyes, he will experience binocular diplopia. Your developmental optometrist can determine whether you have a strabismus and can also recommend a program of optometric vision therapy to help you address it. Many strabismus cases are helped when the individual gains better, more automatic and efficient, control of his eye muscle movement skills.

Convergence Insufficiency

• In order to be able to do near point tasks like reading, writing and sewing without experiencing binocular diplopia or suppressing the visual information from one of the eyes, you have to be able to converge your eyes appropriately. You can illustrate convergence by holding a pencil at arm's length away from your nose so that the point faces up. Look at the pencil. Then slowly bring the pencil toward your nose keeping both eyes on it. You will feel like your eyes are "crossing" as the pencil gets closer and closer. If you cannot keep the image of the pencil single and clear when it is 3 inches or closer to your nose, you may have a binocular vision disorder called convergence insufficiency. If another person sits across from you watching your eyes track the pencil as it gets closer to you, he should be able to observe both of your eyes moving in toward your nose. It should look as that if lines were drawn from the center of each eye to the pencil, they would always be forming an isosceles triangle. If your observer notices that your eyes suddenly widen away from the pencil or one eye moves in or out of alignment, you should ask your developmental optometrist to check whether you have a convergence insufficiency. This may be why you experience words wiggling, blurring or doubling when you read.

Convergence Excess

• Another cause of binocular diplopia is a convergence excess. People who can converge their eyes easily may not be able to relax their eyes when they need a break from a near point task. They often complain of having double vision and headaches. A developmental optometrist can determine if you have a convergence excess and also prescribe a program of in-office optometric vision therapy to address it.

Other Causes

• Diseases can also cause binocular diplopia. Cataracts, Myesthenia Gravis, Grave's Disease, and Multiple Sclerosis all sometimes include symptoms of double vision. Other conditions that may involve binocular diplopia include diabetes, stroke, brain aneurysm, brain tumor and migraines. Of course, severe blows to the head can result in the incidence of double vision as well. If you begin experiencing binocular double vision, make sure that you talk to your medical doctor to rule out any of these conditions. Your developmental optometrist can also help you to decide how to address the visual symptoms. Everyone should have an annual eye examination by a developmental optometrist to monitor their ocular health and visual acuity, and to address any other visual concerns.