Strabismus is the deviation of the eye. It is associated with high amounts of myopia (nearsightedness), hyperopia (farsightedness), and astigmatism.
It can develop after a major illness or injury, but some forms may also be hereditary. Treatment may include prescription eyedrops, eyeglasses or bifocals, or exercises. Exercises or eye patching may be prescribed if amblyopia is present. Surgery may be necessary to completely align the eyes.
The various forms of strabismus are spoken of as tropias, their direction being indicated by the appropriate prefix: cyclotropia, esotropia, exotropia, hypertropia, and hypotropia.
During the first three to six months of life, the eyes tend to waver and turn inward or outward independent of one another. This condition usually corrects itself. However, if it persists, or if the eyes are continually crossed in the same way, even if the child is under six months old, it may be a sign of strabismus; and children do not outgrow strabismus.
In an older child, a tendency to tilt the head when reading, or to close or rub one eye, may be a sign of strabismus. The condition almost always appears at an early age and if not corrected, may impair vision in the nonfocusing eye, as well as marring the child’s appearance. If treated early enough, preferably before six years of age, normal vision can usually be restored.
Strabismus may result from several factors, including a blow to the head, disease, or genetics. Many cases are caused by a malfunction of the muscles that move the eyes, causing them to focus differently, thus sending different images to the brain. As the child grows older, he/she has learned to ignore the image from one eye, which results in one eye being stronger while the other one weakens.
Treatment varies with each individual case. A patch may be placed over the stronger eye for a period of time, forcing the weaker eye to gain strength, if possible. Eye glasses or special exercises may correct the condition. For most eye problems, exercises will not correct them. They will not help nearsightedness, farsightedness, or astigmatism.
These conditions are caused by the actual physical shape of the cornea and the rest of the eye. No exercises can change the shape of the eye much like they cannot change the shape of your teeth. Relying on exercises to “cure” glaucoma, for instance, can only cause a delay in getting the needed treatment in order to prevent blindness. However, exercises do have a place and there are some conditions where exercises will help.
Strabismus is the only common disorder that has a chance of being corrected with exercises. The special exercises for this are known as orthoptic exercises and can be useful when practised under the supervision of a trained orthoptist. In some cases, a relatively simple surgical procedure on the eye muscles may be necessary. Since these muscles are on the outside of the eye itself, there is no danger to vision. A strabotomy is the cutting of an occular tendon in the treatment of strabismus.
There are several types of strabismus:
- Comitant or concomitant strabismus occurs when the angle of deviation of the visual axis in a squinting eye is always the same in relation to the other eye, no matter what the direction of the gaze. This is a result of faulty insertion of the eye muscles during fetal development.
- Convergent strabismus occurs when the visual axes converge, or come together. This is also known as esotropia, or cross-eye.
- Divergent strabismus occurs when the visual axes diverge, or separate and generally causes one eye to turn out toward the ear, it is called exotropia or walleye.
- Noncomitant or nonconcomitant strabismus occurs when the amount of deviation of the squinting eye varies according to the direction in which the eyes are turned.
- Vertical strabismus occurs when the visual axis of the squinting eye deviates in the vertical plane. This is known as hypertropia or hypotropia.
