Strabismus, also called crossed eyes, is a condition in which the eyes do not properly align with each other when looking at an object. Which eye is focused on the object in question can switch. It may also be present occasionally or constantly. If present during a large part of childhood amblyopia may result and depth perception may be lost. Adults may have double vision.
Strabismus can occur due to muscle dysfunction, farsightedness, problems in the brain, trauma, or infections. Risk factors include premature birth, cerebral palsy, and a family history of the condition. Types include esotropia where the eyes are crossed; exotropia where the eyes diverge; and they have hypertropia where they are vertically misaligned. They can also be classified by whether the problem is present in all directions a person looks (comitant) or varies by direction (incomitant). Diagnosis may be made by observing the light reflecting from the person's eyes and finding that it is not centered on the pupil. Another condition that produces similar symptoms is a cranial nerve disease.
Treatment depends on the type of strabismus and the underlying cause. This may include the use of glasses and possibly surgery. Some types benefit from early surgery. Strabismus occurs in about 2% of children. The term is from the Greek strabismós meaning "to squint". Other terms for the condition include "squint", "wall-eye", and "cast of the eye".
Squint, when referring to an abnormality of binocular vision, is another term for strabismus, and also referred to as crossed eye(s) and sometimes lazy eye. Squint and strabismus refer to a condition in which the eyes do not properly align with each other when looking at an object. This term is a little more common in Europe than in the US.
A condition in which the eyes are not properly aligned with each other.
A misalignment of the two eyes when a patient is looking with binocular vision and the two eyes are looking at the same object.
A misalignment of the two eyes that only appears when binocular viewing is broken and the two eyes are no longer looking at the same object.
A tropia is a manifest deviation of the eyes. A phoria is a latent deviation ("un-manifested") between the eyes.
Tropias are unmasked (That is, always visible & not hidden under a mask =P ) Phorias can be unmasked by covering either one of the eyes.
Tropias are diagnosed by the cover-uncover test (Unilateral cover test). Phorias are diagnosed by the cover-cover test (Alternating cover test).
Source: Wikipedia https://en.wikipedia.org/wiki/Strabismus