Cataract is because a person's own lens is opaque and needs to be removed. Removal is equivalent to destroying the integrity of the ophthalmic system. The doctor will calculate an intraocular lens suitable for the diopter of the eye to replace the original lens.

If the eye was emmetropia before removal, it should be hyperopia of+10.00d-+ 12.00d after removal. If intraocular lens is not implanted, corrective glasses with high degree should be worn after operation.