A reduced vision in either or both eyes that persists after correction of any refractive error (i.e. when looking through the optimum glasses) and without any other eye diseases being present. This permanently reduced vision in the eye is not correctable.
It can affect 2-2.5% of the general population. It can be caused by squints (being cross eyed), differences in refraction (or spectacle prescription) between the eyes or high degrees of refractive errors (the need of strong, usually plus glasses), some cases of uncorrected astigmatism and diseases in the eye structures that prevent images getting to the retina.
Reduced vision in either or both eyes. If it occurs in one eye only it may not be noticed. Signs of a squint or other underlying causes may also be present.
Since other eye diseases need to be ruled out, you will need to see your doctor. A full eye examination, including measurement of visual acuity and refraction is required to look for any treatable causes that need correcting such as a need for spectacles. An orthoptic assessment, to measure the amount of squint, is also required for any squints that may be present.
This depends on the cause. It may be correctable to some degree in children with squints and some refractive errors. Treatment options include the correction of any refractive error and occlusion (covering) of the good eye or blurring the vision in the good eye (penalisation) in order to promote the use of the lazy eye.
Individual other lazy eye treatments would also be necessary depending on the cause, such as removal of cataracts, or squint surgery at the appropriate stage. Many eyes can show some improvement in vision even to a level equal to the good eye, but the majority of eyes still have some residual amblyopia. Eyes that show no improvement may require further investigations to exclude other underlying causes.