Seeing double vision is clinically known as diplopia. There are two types of diplopia: monocular and binocular. Different treatments should be sought according to the different causes. Monocular diplopia is mainly caused by some lesions of the eye itself. For example, regular astigmatism of the cornea at birth, irregular astigmatism of the cornea due to corneal diseases (such as scar, inflammation, cone cornea), irregular astigmatism of the cornea due to compression of the eye by larger ocular face cysts or tumors, cataract, and lens dislocation can all cause monocular diplopia. In addition, monocular diplopia can also be seen with macular edema caused by local or systemic diseases, certain central nervous diseases, etc. Binocular diplopia is most commonly associated with abnormal eye position due to paralytic strabismus. In addition, binocular diplopia can also be seen in patients with systemic or local lesions caused by oculomotor disorders, visual center-induced binocular fusion disorders, and after surgical correction of strabismus patients with abnormal retinal counterparts. Refractive errors, such as the optical center of the lens does not match the pupil distance, can also cause diplopia. From the above, we can learn that there are many reasons for double vision, so we should go to the hospital in time to find out the cause of double vision and treat the cause in time, so that we can recover. For example, for monocular diplopia, treatment of eye diseases, glasses, cataract surgery, etc.; for binocular diplopia, prism glasses for small strabismus, eye muscle surgery for large strabismus, treatment of myasthenia gravis, medication or surgery for cerebral nerve or brain lesions.