Accommodative esotropias are a type of convergent strabismus that usually develops between the ages of 18 and 36 months of age. Frequently there is a family history of a strabismus, childhood refractive error (usually hyperopia) or amblyopia.

Why does this strabismus occur? Children who develop an accommodative strabismus are invariably long sighted and as a result of their long sightedness they have to exert extra focusing to bring a near object into sharp focus. If a child is long sighted they have to accommodate more to bring a close object into sharp focus, but as a result they will automatically converge more than is necessary and may develop an accommodative esotropia.

Some of the features of accommodative esotropia:

• Hyperopia: The vast majority of children with an accommodative esotropia are farsighted and will require full-time spectacle wear. In many children the degree of hyperiopa is symmetrical, but in others one eye may be more hyperopic than the other. 
• A convergent strabismus that is normally larger when the child is focusing on an object close to them.

Initially the child will have an alternating strabismus, which means they will occasionally use their right eye while the left eye is turned inwards, and then swap to use their left eye with the right turning inward. However, many children very quickly tend to favor one eye over the other and will permanently switch off (suppress) the image from the in turned eye, causing this eye to become amblyopic. If the amblyopia is treated successfully the child will no longer have a dominant eye and will happily alternate gaze from eye to the other

An upward movement of the eye(s) when the child looks to the opposite side is often seen in children with partially accommodative esotropias. This is caused by an overaction of a muscle called the inferior oblique muscle. If the angle of the esotropia is fully corrected with glasses the strabismus is said to be a “fully” accommodative esotropia. These children normally have excellent stereopsis and do not develop amblyopia.

If the angle of the strabismus is not fully corrected with glasses it is called a “partially” accommodative esotropia.

Some children have a large angle convergent strabismus when they are looking at a near object, but their eyes are straight or almost straight when they are looking at a distant target. This is known as a convergence excess esotropia. Children with this form of esotropia potentially have good stereopsis if their strabismus is corrected with bifocal glasses or surgery.

If there is no change in the angle of the strabismus with glasses, the strabismus is said to be a nonaccommodative esotropia.

Republished, with permission, from www.squintclinic.com.