Horizontal comitant strabismus forms the single largest group of strabismus we encounter routinely. In spite of their clinical abundance, varied presentation makes this subtype challenging even for an experienced observer.
Broadly speaking, a horizontal comitant deviation could be either esotropia (ET) or exotropia (XT) depending on whether either eye deviates inwards (nasally) or outwards (temporally). The literal meaning of ‘committance’ is to be pledged or to accompany in a subordinate way. Both the eyes (are pledged each other and) have equal deviation in all directions of gaze for a given fixation distance. The seat of anomaly is usually the brain unlike incomitant deviations which arise out of defect in the neuro muscular complex.
Dynamic mechanisms (e.g. accommodation, fusional vergence) may be superimposed or may mask the deviation. Residents often confuse esotropia to be the opposite of exotropia; however, they should be considered as totally different entities.
KeywordsAccommodative esotropia Infantile esotropia Intermittent exotropia Newcastle score Simulated divergence
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