Strabismus

Strabismus refers to any misalignment of the eyes. Eye muscle surgery is used to repair strabismus. Each eye is normally moved by the coordinated effort of six muscles that are attached to the outer surface of the eye (extraocular muscles). When these muscles are damaged or diseased they will not work properly. Surgically moving the attachment of the extraocular muscles can correct the position and movement of the eye. Depending upon the specific misalignment, a single muscle or a group of muscles can be moved to achieve the desired position of the eyes.

Eye muscle surgery is performed using small sutures and micro-surgical instruments. Lasers are not used in eye muscle surgery. Most surgeons use absorbable sutures. Adjustable suture strabismus surgery is sometimes employed to permit a fine-tuning of the position of the eyes after the anesthetic has worn off. To do this, sutures are left loosely tied for up to one day following the surgery. Then the patient is checked in the office and adjustments are made depending upon the alignment of the eyes. This technique is best suited for cooperative adults and has permitted improved surgical results.

Anesthesia for strabismus surgery depends on a variety of factors. In general, strabismus surgery on children is done under general anesthesia as an outpatient surgery. For adults, local anesthesia or general anesthesia may be employed. Most surgeons will recheck their patients in the office on the first or second day after surgery.

In adults, the common causes of strabismus include weakness of an extraocular muscle, stroke and other brain disorders, and problems in the eye socket such as tumors or trauma. Acquired strabismus in the adult usually causes double vision, which goes away with one eye closed. Fortunately many of the causes of double vision in adults will mend themselves in time. Other causes may require the use of ophthalmic prisms or eye muscle surgery.

In children, most instances of strabismus result from poor coordination of movements between the eyes. The misalignment may be apparent shortly after birth or may be acquired later in childhood. Imperfect alignment in children is of concern for a number of reasons. First, it prevents normal binocular vision and depth perception. Second, because the visual system is developing, the normal eye-to-brain neural connections are prevented from developing normally. A great concern in children with ocular misalignment is that one eye will become dominant and the other less favored through the phenomenon called suppression. The deviating "suppressed" eye is at risk to undergo loss of vision called amblyopia. Children are much less likely than adults to develop double vision because of suppression. Rather, they simply utilize the stronger eye while the other deviates without contributing to functional vision.

Amblyopia and strabismus are of great concern to the pediatric ophthalmologist as they can cause lifelong visual impairment. The conditions are interrelated and one may lead to the other. We try to avoid using the term "lazy eye" because it is not clear whether the term is being used to refer to a deviating eye (strabismus), a weak eye in terms of vision (amblyopia), or both. However, the key to optimum treatment of amblyopia and strabismus is early detection. This is due to the fact that as the child ages the developing brain becomes less flexible or plastic in its ability to recapture normal development.

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