Esotropia is one of the many disorders of the eye covered by “strabismus”, which is the general medical term used to cover all the various types of squinting that can be found in the eye – so many that there are several ways of classifying them.

One of the classifications puts the types of strabismus into two basic groups – “paralytic” and for want of a better alternative it seems “other”.

Esotropia falls into the group “other”, with the group including exotropia, hypertropia, heterophoria syndrome and Duane syndrome. The main factor initiating the grouping is the designation according to the combinations of directions of squinting that can occur:

• Esotropia – either one both of the eyes turns inwards, never both at the same time
• Exotropia – either one of both of the eyes turns outwards
• Hypertropia and hypotropia – one eye points up or down respectively (a vertical type of strabismus)

The general term strabismus covers then a wide range of eye movement disorders, and there are quite a few colloquial names including “google-eye”, “crossed-eyes” and “boss-eye” to name but a few.

There are several ways of describing esotrope (the plural of esotropia):

Esotropia – according to which eye

As if the classification system wasn’t complicated enough, esotropia itself can be further classified with regard to the eye considered to be doing the squinting; however, both eyes never squint together in the same direction.

With “left” esotropia it’s obviously the left eye that squints, with “right” esotropia it’s the right and with “alternating” esotropia the eyes take turns to squint whilst the non squinting eye turns inward.

Esotropia – according to amount

And then a further classification:

Concomitant – where the degree of turning of the eye doesn’t change with the direction of sight (these can be further classified into ones that change intermittently or do not change).

Incomitant – where the direction of gaze does have an effect on the degree

Esotropia – according to cause

• Primary – caused by an initial problem, the biggest category

• Secondary – originating from change in overall vision

• Consecutive – after an overcorrection treatment of an exotropia, where the eyes were turning outwards originally

Treatment of the various Esotropias

A treatment protocol will need to be devised for each type of esotropia individually – hence the need for the exhaustive range of classifications as above to assist in identification.

Spectacles are usually prescribed and the patient needs to be carefully monitored during the “settling in” phase; eye patches may also be prescribed to be used in conjunction with the spectacles.

As part of the treatment process a program of eye exercises should be introduced to assist the eyes to work together.

Surgery on one of the six muscles that control eye movement is an option if spectacles and exercise therapy fails to produce the desired results.

The surgery itself only requires attendance at a day clinic, and it’s usual to co-ordinate the procedure with spectacles again to assist. Follow-up sessions need to assess eye performance since eyes may have become aligned satisfactorily but overall vision might not have been corrected adequately.

And finally – “Botox” injections can sometimes be applied to muscles to provide a permanent or temporary remedy.