Where a patient tends to consistently fixate with one eye and squint with the other, the eye that squints is likely to develop some amblyopia. Someone whose squint alternates is very unlikely to develop amblyopia because both eyes will receive equal visual stimulation. It is possible to encourage alternation through the use of occlusion or patching of the dominant or fixating eye to promote the use of the other. Esotropia is a highly prevalent congenital condition. Concomitant versus incomitant
Esotropias can be concomitant, where the size of the deviation does not vary with direction of gaze—or incomitant, where the direction of gaze does affect the size, or indeed presence, of the esotropia. The majority of esotropias are concomitant and begin early in childhood, typically between the ages of 2 to 4 years. Incomitant esotropias occur both in childhood and adulthood as a result of neurological, mechanical or myogenic problems affecting the muscles controlling eye movements. Primary, secondary or consecutive
Concomitant esotropias can arise as an initial problem, in which case they are designated as "primary," as a consequence of loss or impairment of vision, in which case they are designated as "secondary," or following overcorrection of an initial exotropia in which case they are described as being "consecutive". The vast majority of esotropias are primary. Treatment
The prognosis for each patient with esotropia will depend upon the origin and classification of their condition. However, in general, management will take the following course:

Identify and treat any underlying systemic condition.
Some ophthalmologists favour an early surgical approach as offering the best prospect of binocularity whilst others remain unconvinced that the prospects of achieving this result are good enough to justify the increased complexity and risk associated with operating on those under the age of one year. Incomitant esotropia
Incomitant esotropias are conditions in which the esotropia varies in size with direction of gaze. They can occur in both childhood and adulthood, and arise as a result of neurological, mechanical or myogenic problems. These problems may directly affect the extra-ocular muscles themselves, and may also result from conditions affecting the nerve or blood supply to these muscles or the bony orbital structures surrounding them. Examples of conditions giving rise to an esotropia might include a VIth cranial nerve (or Abducens) palsy, Duanes syndrome or orbital injury. Diagnosis
Classification
Right, left or alternating
Someone with esotropia will squint with either the right or the left eye but never with both eyes simultaneously. In a left esotropia, the left eye squints, and in a right esotropia the right eye squints. In an alternating esotropia, the patient is able to alternate fixation between their right and left eye so that at one moment the right eye fixates and the left eye turns inward, and at the next the left eye fixates and the right turns inward. This alteration between the left and right eye is mostly spontaneous, but may be voluntary in some cases.