By Mitchell Strominger, MD
Director, Pediatric Ophthalmology and Strabismus Service
Strabismus is the scientific term used to describe eye misalignment or eye turn. This condition is also known as "wandering eye" or "crossed eye." More than four percent of adults have strabismus. In many patients the problem began in childhood.
There are two types of strabismus. An inward turning ("esotropia") of the eye can occur at or near birth (infantile esotropia) or sometime after 2 years of age, with the need for glasses correction (accommodative esotropia). In some children who are farsighted and do not have glasses, their eyes can turn in, even further.
The other form of eye misalignment is exotropia, in which the eye turns out. Most commonly exotropia starts as an intermittent turn that later progresses to a full misalignment. It can also be associated with asymmetric glasses prescription, or an eye with a structural abnormality. In children with strabismus, depth perception is lost. The deviated eye can also develop into a lazy eye ("amblyopic") in which the vision turns off because of the ch i Id's avoidance of double vision. Despite proper treatment in childhood including surgery to straighten the eye, some 20 percent slowly drift over time, creating adult strabismus.
Other common reasons for adult strabismus are illness or accidents. Many severe illnesses disrupt the normal ability to keep the eyes together. These patients experience constant diplopia, in which the eyes are misaligned. Strabismus can also occur after injury to the cranial nerves following an accident, stroke or another neurological insult.
Three cranial nerves- three, four and six- control the six eye muscles. Any injury to these cranial nerves leads to ocular misalignment. Again, if vision is good, diplopia can occur. Another common disorder that leads to adult strabismus is thyroid orbitopathy (a lso known as Continued on page 8 Strabismus: Never too late to correct Continued from page 3 Grave's disease). In this instance, instead of a problem with the nerves innervating the muscles, the muscles themselves become thick and fibrotic, thus affecting movement. Patients with Grave's disease can often have progression of eye problems despite good control of their thyroid function.
Adult strabismus can lead to other difficulties besides double vision . Ocular alignment is important for binocularity and stereopsis. These patients cannot see "3-D" and subsequently have difficulty with their depth perception. In instances where a person developed strabismus as a child and the eye slowly drifts out, binocularity can be reestablished following ocular alignment as an adult.
Field of vision (peripheral or side vision) is also limited when an eye is turned. This peripheral vision is important in detecting objects off to the side especially when driving. In a patient whose eyes are turned inward (esotropia) the visual field can be expanded when the eyes are realigned.
In addition to affecting ocular function, strabismus can interfere with normal communication and social interaction by impeding normal eye-to-eye contact. Patients can develop head postures to eliminate eye contact and impair self-confidence. They look away when speaking and the person being spoken to is often uncertain as to which eye the strabismic patient is using. This leads to a problem with communication. Because communication skills are key to success in many professions, strabismus can lead to limited job and advancement opportunities. Studies have also shown that patients with strabismus are less likely to be hired for a job and are perceived as less intelligent.
After the proper spectacle and possible prism correction, the vast majority of patients with larger angle strabismus can undergo surgical realignment, leading to significant improvement. Most surgery is done in one day as an outpatient. Although general anesthesia is used in many cases, regional anesthesia is equally effective. The procedure entails isolating the extraocular muscles and realigning them by placing them at different positions on the eye covering (sclera). Postoperatively, most surgeons ask their patients to utilize topical antibiotic drops to prevent infection. Discomfort is typically mild and the eyes heal very quickly, usually within days to weeks. In some instances an adjustable technique is utilized so that refinement can be made when the patient awakens.
The field of adult strabismus continues to evolve. Newer strategies include treating childhood strabismus to prevent progression into adulthood, improving binocularity and peripheral vision, and ocular realignment following the development of neurological or other ocular insults. Since strabismus is an abnormal condition that affects patients from both a functional and social standpoint, its repair should not be considered "cosmetic" but more importantly reconstructive or restorative .
Mitchell Strominger, MD, is director of the Pediatric Ophthalmologyand Strabismus Service at the Floating Hospital for Children's New England Eye Center and associate professor at Tufts University School of Medicine. He can be reached at (617) 636-6769.
The Pediatric Ophthalmology and Strabismus Service is located in the same office as the Electrophysiology Service, which measures vision in preverbal children using visual evoked potentials and preferential looking techniques.
Pediatric patients with cataracts, glaucoma, corneal and retinal disorders are provided a full range of diagnostic and therapeutic services in conjunction with other New England
Schedule an appointment or contact us at 617-636-6769.