An Observational Study of Infantile, Acquired Non-accommodative, and Acquired Partially-accommodative Esotropia

Inclusion Criteria: For infantile ET: * Less than 12 months old * Duration of esotropia less than 6 months by best estimate (photos, parent history, physician records) * A constant or variable esotropia * Onset before six months of age * Measuring \>10 PD by Alternate Prism and Cover Test (APCT) in the primary position at distance fixation on an accommodative target * Gestational age \> 34 weeks * Birth weight \> 1500 grams For ANAET: * 6 months to \<5 years old * Duration of esotropia less than 6 months by best estimate (photos, parent history, physician records) * A constant or variable esotropia * Onset after six months of age * Angle decreases less than 10 prism diopters (PD) by Alternate Prism and Cover Test (APCT) in the primary position at distance fixation with correction * Residual angle measures \>10 PD by Simultaneous Prism and Cover Test (SPCT) in the primary position at distance fixation * For patients who have significant refractive error, full hyperopic correction determined with cycloplegia must have been worn for at least 2 weeks. * For patients who do not have significant refractive error, whether to prescribe spectacles is at investigator discretion, however, if the investigator elects to prescribe spectacles, the full hyperopic correction determined with cycloplegia must have been worn for at least 2 weeks * Gestational age \> 34 weeks * Birth weight \> 1500 grams For APAET: * Onset after six months of age * 6 months to \<5 years old * Duration of es…