Esotropia

Overview

Esotropia is a type of strabismus or eye misalignment. In esotropia, the eyes are crossed, i.e. while one eye looks straight ahead, the other eye is turned toward the nose. This inward deviation can begin in infancy or later in childhood.

Pseudoesotropia

Pseudoesotropia refers to the appearance of crossed eyes in a child whose eyes are actually perfectly aligned. This is common in infants and younger children who have a broad, flat bridge of the nose, which allows the skin on the inner part of the eyelids to extend over and cover the inner part of the eye. This gives the appearance of a crossed eye, when none is actually present. As the face matures and the nasal bones grow, the skin is pulled forward and away from the eye, eliminating the crossed eye appearance.

Congenital Esotropia

Congenital or infantile esotropia occurs in the first 6 months of life. In the first weeks or months of life, it is common for eyes to intermittently become misaligned. If the misalignment persists after the first few months, an eye examination is necessary.

One to two percent of children have congenital esotropia. Though the cause is unknown, it is thought that the problem is in the brain's inability to coordinate the movement of the eyes, which are themselves most commonly completely normal. These children will often alternate their vision between the two eyes by sometimes crossing one and at other times the other. Some children will constantly cross the same eye. This is often an indication that amblyopia, or decreased vision, is developing in one eye.

Children do not outgrow congenital esotropia. Surgical correction is usually recommended between 6-14 months of age. Early alignment of the eyes allows for the development of brain to eye communication, which results in enhanced depth perception, fine motor skills, and the best opportunity to maintain good eye alignment throughout life. Before surgery is performed, other factors must be considered. If amblyopia has developed in one eye, then patching the better eye is necessary to force the brain to use the eye with poorer vision. This will not correct the crossing, but will equalize vision and improve the likelihood of a successful surgical outcome.

Acquired Esotropia

Acquired esotropia refers to esotropia that occurs after infancy and is not responsive to farsighted glasses. There are multiple causes. Most common are children who have been farsighted for awhile and have not had glasses, or children who were initially responsive to glasses but later developed an additional eye crossing even with the proper glasses. Treatment involves eye muscle surgery.

Accommodative Esotropia

Accommodative esotropia refers to esotropia caused by farsightedness. Children who are farsighted easily and automatically focus on objects at distance and near through a process called accommodation, in which a muscle inside the eye changes the shape of the eye's natural lens and allows images to focus properly on the retina. However, in some children who are farsighted, this accommodative effort is associated with a reflex crossing of the eyes.

Accommodative esotropia can begin anywhere from 6 months to 6 years of age. The usual age of onset is between 2 and 3 years of age. The crossing may only be evident when your child intently views an object at near or when your child is tired or not feeling well. Some children will complain of double vision or may be seen squinting or rubbing one of the eyes.

Treatment involves the full-time use of the appropriate farsighted glasses. The glasses will focus the images, thereby making accommodation unnecessary. Sometimes the glasses will only cause the crossing to disappear when your child looks at the distance; crossing may persist when gazing at near objects. In these circumstances, a bifocal lens is usually prescribed.

It is not uncommon that children with accommodative esotropia will have amblyopia. If this is present, patching may be required. The glasses must also be worn when using the patch.

If glasses control the crossing of the eyes, eye muscle surgery is never recommended. If the crossing is not controlled, or if children whose esotropia was previously controlled with glasses "deteriorate" and begin to cross again, then eye muscle surgery may be required to establish good ocular alignment.

Children may outgrow their accommodative esotropia. While the degree of farsightedness often increases gradually until 8 years of age, it typically diminishes each year afterwards. Many children will be able to maintain straight eyes without glasses in their early teen years. Some children will no longer need their glasses at an earlier age, while others will need the proper glasses or contact lenses to control the esotropia even as adults.