In strabismus, commonly known as ‘crossed eyes’ or ‘wall eyes’, a person’s eyes are not in alignment. One eye may turn either inward, outward, upward or downward. The eye turn may be present at all times, or may only appear when a person is tired at the end of a day, ill, or concentrating intensely on an object.

If the brain was to continue to use both eyes, a person would see double. When this occurs, the brain choses to ignore the image and messages from the turned eye. This is a condition called suppression. When suppression occurs for any length of time, another adaptation may occur. The suppressing eye may become ‘lazy’ or amblyopic.