Esotropia is an eye condition wherein one or both eyes turn inward. The term comes from the Greek eso which means “inward” and trope which means “turning”. It is a form of strabismus, the condition of the eyes not properly aligning when focusing on an object. It is the opposite of exotropia where the eyes turn outward. It is also sometimes mistakenly called "lazy eye", which describes the condition of amblyopia, the reduction of vision. Amblyopia can however, happen as a result of esotropia occurring in childhood. Persons with esotropia may notice that they are unable to focus their eyes on the same object or place at the same time, and they may only be able to see objects fully with one eye. Symptoms include diplopia or double vision, decreased binocular vision (the ability of the eyes to focus together), and difficulty to perceive depth.
There are different types of esotropia. These are concomitant esotropia, where the inward squint does not change with the direction of sight; incomitant esotropia, where the inward movement does change with the direction of the gaze; accommodative esotropia, also called refractive esotropia, where the eyes turn inward due to the effort of focusing on objects; and congenital or infantile esotropia, where the condition occurs between birth and six months, as opposed to acquired esotropia which is commonly the case in people with esotropia.