What is Strabismus?
Strabismus is a visual defect in which the eyes are misaligned and point in different directions. One eye may look straight ahead, while the other eye turns inward, outward, upward or downward.
ESOTROPIA - or "crossed eyes" is the condition in which an eye turns inward either intermittently or constantly.
EXOTROPIA - or "wall eye" is the condition in which an eye turns outward either intermittently or constantly.
HYPERTROPIA - one eye turns upward
HYPOTROPIA - one eye turns downward
AMBLYOPIA - Abnormal eye alignment, as in strabismus, may cause reduced vision or amblyopia. The brain will recognize the image of a better seeing eye and ignore the image of the weaker or amblyopic eye. This is thought to represent an abnormal adaption to deal with the confusion of double vision.
What are the symptoms of Strabismus?
The most immediate indication of strabismus is that one, or both, eyes do not appear to be looking straight ahead. Sometimes a child will squint one eye in bright sunlight or tilt their head in a specific direction to use their eyes together. Signs of faulty depth perception may also be noticed.
What causes Strabismus?
The exact cause of eye deviation is unclear, but eyes are known to deviate because of inherited or acquired abnormalities. Conditions which may cause ocular deviation include:
- Excessive farsightedness
- Developmental abnormalities
- Injury to the eye or brain at birth
- Loss of vision in one eye
- Any disease which affects the eye muscle directly or a portion of the brain which controls the eye muscles or movement of the eyes
Eyes that are deviated at birth may be due to inherited, genetic defects or other unknown causes. Deviations that are present at birth rarely straighten with passage of time, and they usually require eye muscle surgery to align (straighten) the eyes. Some random, intermittent, uncoordinated eye movement may normally occur in infants up to the age of 3 to 4 months, but will resolve by 6 months.
How is Strabismus treated?
There are few conditions in the field of medicine which demand greater cooperation between parents and physicians than the care of children with eye muscle problems. Treatment goals for strabismus are to preserve vision, to straighten the eyes, and to restore binocular vision (vision by both eyes). Depending on the cause of the strabismus, treatment may involve repositioning the unbalanced eye muscles, removing a cataract, or correcting other conditions which are causing the eyes to turn. After a complete eye examination, including a detailed study of the inner parts of the eye, we can recommend appropriate optical, medical or surgical therapy.
Covering or patching the good eye to improve vision in the amblyopic eye is often necessary. Patching of the unaffected eye is initiated to help the "lazy eye" become visually stronger. If amblyopia is detected in the first few years of life, treatment is often successful. Patch therapy is useful up the age 9 or 10, and in some cases older. If adequate treatment is delayed until later, amblyopia or reduced vision generally becomes permanent. As a rule, the earlier amblyopia is treated, the better the visual result.
Strabismus surgery involves making a small incision in the tissue covering the eye,or conjunctiva, which allows the ophthalmologist access to the underlying eye muscles. Which eye muscles are repositioned during the surgery depends upon the direction the eye is turning. Surgery on one or both eyes may be necessary. When strabismus surgery is performed on children, a general anesthetic is required. Recovery time is rapid. Children are usually able to resume their normal activities within a few days. Early surgery is recommended to correct strabismus because younger infants can develop normal sight and binocular vision once the eyes are straightened. As a child gets older, the chance of developing normal sight and binocular vision decreases, although side vision may improve. Crossed eyes can also have a negative effect on a child's self-confidence.