Corneal ring implants are clear pieces of plastic that can be surgically implanted into the clear, dome-shaped bulge at the front of the eye called the cornea. The implants flatten the cornea and reduce nearsightedness. The implants are shaped like crescents or half-circles. After you get local anesthesia, two implants are inserted in each eye, along the sides of the cornea. They do not cover the central portion of the cornea.
Corneal implants are intended to be permanent. But they can be surgically removed if you are not happy with the results.
What To Expect After Surgery
Surgical insertion of corneal ring implants is done on an outpatient basis. This means that you do not have to stay overnight in the hospital. The visual effects of the implants are immediate.
After surgery, you may wear a patch or contact lens on the eye and may get a prescription for pain medicine. Someone must drive you home and then back to the surgeon's office the next day. During this second visit, the surgeon will examine your eye and prescribe eyedrops to prevent infection and reduce inflammation. More follow-up visits are required, usually the next week and then throughout the first year after surgery.
Why It Is Done
The U.S. Food and Drug Administration (FDA) has approved corneal ring implants for use in adults age 21 and older with mild nearsightedness (1 to 3 diopters) who have mild or no astigmatism (1 diopter or less) and whose vision has been stable for at least 1 year. Corneal ring implants can also be used to treat certain diseases of the cornea (such as keratoconus and thinning of the cornea).
How Well It Works
Corneal ring implants appear to be very effective for correcting mild nearsightedness. A year after having corneal ring implants inserted, 88 out of 100 people had uncorrected vision (without glasses or contact lenses) of 20/40 or better.footnote 1
They have not been studied or approved for use in treating moderate or severe nearsightedness. There is no information about the long-term results of corneal ring implants.
Complications of corneal ring implants may include:
Experts do not yet know if there are long-term risks from corneal ring implants.
What To Think About
One advantage that corneal ring implants have over laser surgery is that the procedure can be reversed by having the rings removed at any time.
If you are thinking about having surgery to improve nearsightedness, consider all the options, which include corneal ring implants, intraocular lens implants, PRK, LASIK, and radial keratotomy. Talk about these options with your doctor.
Kojima T, et al. (2009). Intrastromal corneal ring segments for low and high myopia. In M Yanoff, JS Duker, eds., Ophthalmology, 3rd ed., pp. 181–185. Edinburgh: Mosby Elsevier.
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