Esotropia is a type of strabismus (eye misalignment) in which one or both eyes cross or turn inward.
There are two main types of esotropia. The first is infantile esotropia and it appears at a very early age, usually by 6 to 12 months. The second type, acquired esotropia, appears any time from 1 to 8 years of age, but usually between 2 and 5 years old.
Infantile esotropia may initially seem intermittent or small, but quickly becomes a constant crossing of the eyes which is fairly large in magnitude. Most of these infants cross both eyes equally, but occasionally will cross one eye more frequently or more severely than the other.
The cause of infantile esotropia is unknown, but it runs in families and there is a genetic predisposition. Treatment for infantile esotropia is almost always surgical. This involves loosening or weakening the inner (medial rectus) muscles in order to straighten the eyes. This type of esotropia can almost never be corrected with glasses alone, though glasses and surgery may be required if a child is extremely farsighted.
If the child crosses one eye more than the other, this may be a sign of amblyopia or “lazy eye.” In this case, patching the stronger eye may correct the vision while surgery helps straighten the eyes. The worse the vision, the more patching required to correct it. Amblyopia occurs more frequently in acquired esotropia than in infantile esotropia.
Acquired esotropia occurs in children who develop crossed eyes after age 1 or 2. In many of these children the crossing is caused by a refractive error or farsightedness and can be corrected with glasses.
Farsightedness (hypermetropia) causes the eyes to cross because the child has to strain to focus and see. Glasses eliminate the need to focus, correcting the crossing. Bifocal glasses are occasionally needed if the eyes cross more when looking close rather than at distant objects. Even if glasses do correct the crossing, the eyes will still cross when the glasses are not being worn.
Surgery on the eye muscles may be required if your child's eyesight isn't fully corrected with glasses. Surgery is more likely in children who have had uncorrected esotropia for a long time and in children who have developed amblyopia or “lazy eye.” Patching of the stronger eye will be required in addition to glasses and/or surgery if your child has "lazy eye."
If glasses do not correct the crossing in six to eight weeks, surgery will generally be recommended. Most children whose eyes are straightened with glasses will require them throughout childhood, although many of them may outgrow the glasses when they reach 7 to 8 years old. If the glasses are no longer straightening the eyes, surgery may be recommended at any time during childhood.