What commonly causes a lazy eye and one side of the body to be weaker?

Lazy Eye. Lazy eye may be related to amblyopia, where one eye is stronger than the other. Most commonly, one eye is turned in or out. If this happens in early childhood, patients will develop a suppression scotoma and will not develop double vision. Later in life, an acquired strabismus may cause double vision. Amblyopic can also be caused by a refractive difference between eyes or a cataract or ptosis.
Development. A lazy eye often occurs in otherwise healthy individuals. If the side of the body that has the lazy eye also has significany weakness, it may be related to a developmental condition. If these conditions have recently occurred, you should see your doctor as soon as possible to rule out other medical conditions.