Lazy Eye (amblyopia) is reduced vision from lack of use in an otherwise normal eye. It usually happens only in one eye. Any condition that prevents a clear image can interfere with the development of vision and result in amblyopia. Amblyopia is common, affecting about 2% of children. Some causes of amblyopia include strabismus, droopy eyelids (ptosis), cataracts, or refractive errors. Because early treatment offers the best results, consult an ophthalmologist.