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, Duane's syndrome or orbital injury.
Concomitant was introduced into English at a time when many people were criticizing the use of Latinate forms in favor of more "native" words from Old English. As a descendant of Latin concomitari ("to accompany") and ultimately of "comes," the Latin word for companion, "concomitant" may well have been initially derided as an ostentatious inkhorn term. Indeed, two associated words, the verb concomitate, meaning "to accompany," and another adjective, concomitaneous, meaning "of a concomitant nature," didn't survive to accompany "concomitant" into the 18th century.