Jan. 26, 2000 (Tuscaloosa, Ala.) -- In children with a condition called strabismus, developmental delays occur twice as often in those from low-income families on Medicaid than in children from families above the poverty line. That's according to a study in the Journal of the American Association for Pediatric Ophthalmology and Strabismus (Journal of AAPOS).
Strabismus, a condition in which the eyes are not aligned, occurs because of weakness or overaction of a muscle controlling the position of one eye. One eye will appear straight while the other eye turns inward, outward, upward, or downward, according to the American Academy of Pediatrics.
Byron Demorest, MD, explains that strabismus is sometimes called 'the squint'. "The reason for the squint is that children who have an eye that is not straight -- either deviated out or in -- often have glare in that eye so they squint," says Demorest. Strabismic deviations include exotropia (one eye turns outward toward the ear, a condition also known as walleye) and esotropia (when one eye turns inward, the condition commonly known as cross-eyed).
The AAPOS journal article, from the departments of ophthalmology and pediatrics at Albany (N.Y.) Medical Center, points out, "Strabismus and poverty are common among developmentally delayed children." Furthermore, John Simon, MD, one of the study authors, tells WebMD, "Children with development delay disorders such as cerebral palsy or hydrocephalus may have 10 times the incidence of strabismus compared to children from the general population." Examples of developmental delays include delays in learning to walk and talk.
Demorest, professor of ophthalmology at the University of California, Davis, agrees that children from low-income families are more likely to have developmental delay disorders, perhaps because the mothers of such children tend get inadequate pre-natal care. However, no one know what causes strabismus or why low-income children are more susceptible.
According to the American Academy of Ophthalmology, strabismus can cause reduced vision, also known as amblyopia, in the weaker eye. With normal vision, both eyes aim at the same spot. The brain then fuses the two pictures in a single, three-dimensional image, yielding depth perception. When one eye crosses, two different pictures are sent to the brain. Often the brain will recognize the image of the better-seeing eye and ignore the image of the weaker or amblyopic eye. This occurs in approximately half the children who have strabismus. Amblyopia can be treated by putting a patch over the "good" eye, which forces the weaker eye to "accommodate," thus improving vision, says Simon.
Treatments for strabismus includes corrective lenses, Botox (a drug that is injected and temporarily relaxes the eye muscle, allowing the opposite muscle to tighten and straighten the eye), and surgery. However, for developmentally delayed children -- especially those who have developmental disorders due to Down's syndrome, cerebral palsy, or hydrocephalus -- surgery is often the best treatment, according to Demorest.
During surgery, the ophthalmologist makes a small incision in the tissue covering the eye to reach the eye muscles. These muscles are repositioned, depending on which direction the eye is turning.
"Children with neurodevelopmental delays, regardless of their socioeconomic class, are less predictable in their responses to medical and surgical treatment simply because their neuromuscular systems are not normal," Gary T. Denslow, MD, clinical professor of pediatric ophthalmology at the Children's Center at St. Francis Hospital in Tulsa, Okla., tells WebMD.
Simon agrees. "These patients do tend to be a little more unpredictable in their responses to treatment, including surgery," he says, "so we tend to be more conservative in doing surgery on these patients. If we moved the muscles in these patients as much as we do in normal patients, they tend to be overcorrected, so less is more with these patients."
When strabismus surgery is performed on children, a general anesthetic is required. Recovery time is rapid. According to a patient information document by the American Academy of Ophthalmology, patients "are usually able to resume their normal activities with a few days."