Constant esotropia occurring before 6 months of age. It is typically associated with a large angle of deviation, alternating fixation (therefore low risk of amblyopia) and poor potential for binocular single vision. Other features that might be present in individuals with infantile (constant) esotropia include latent nystagmus or manifest latent nystagmus, dissociated vertical divergence, cyclotropia, abnormal head posture, limited abduction. [from
HPO]