Lazy eye is the common term used for what optometrists call strabismus. It refers to the eye/eyes that is/are turned in or out either sometimes or constantly. Lazy eye occurs in childhood when there is a big difference between the prescription of the eyes (causing the brain to ignore the information from the eye with the blurrier vision causing it to turn in/out). It can also be caused by a defect in the muscle system of one eye (either too weak or too strong).
An eye glass prescription is often the first line of treatment for a lazy eye, then patching and vision therapy (eye exercises), and lastly surgery (not possible for all cases). Each individual is assessed and treated accordingly. The goal of glasses is to make sure both eyes are seeing a clear image that is sent to the brain. Once vision has stabilized, patching of the good eye is initiated to attempt to teach the bad eye to see clearly. In order for this procedure to be successful, the patching must be done consistently and correctly according to the directions from the optometrist. Vision therapy is also a treatment option for those with eye muscle issues. These exercises aim to strengthen the weaker muscles to bring the eyes into alignment or to help children to learn to use their eyes together more efficiently. Vision therapy must also be done on a consistent basis to be successful. Eye muscle surgery is usually for cosmetic reasons or a last resort since it is hard for ophthalmologists to accurately estimate exactly where the eye will align.