Echothiophate iodide reduces pressure in the eye by increasing the amount of fluid that drains from the eye. This also causes the pupil to become smaller, reducing its response to light or dark conditions. Echothiophate iodide ophthalmic (for the eyes) is used to treat glaucoma, especially after cataract surgery. This medicine is also used to treat certain eye-focusing disorders. Echothiophate iodide ophthalmic may also be used for purposes not listed in this medication guide.