Corneal Ring Implants for Nearsightedness (Myopia)

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Corneal Ring Implants for Nearsightedness (Myopia)

Surgery Overview

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. 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.

Why It Is Done

Corneal ring implants are used to correct vision in adults 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.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:

  • Infection.
  • Glare or halos.
  • Night vision problems.
  • Overcorrection or undercorrection.

Experts do not yet know if there are long-term risks from corneal ring implants.

What To Think About

Some people have had the implants removed because of unacceptable side effects, such as severe glare, or because they were not happy with the vision provided by the implants (overcorrection or undercorrection).

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.

Complete the surgery information form (PDF) (What is a PDF document?) to help you prepare for this surgery.



  1. Azar DT, Primack JD (2004). Intrastromal corneal ring segments for low and high myopia. In M Yanoff et al., eds., Ophthalmology, 2nd ed., pp. 212–217. St. Louis: Mosby.


By Healthwise Staff
Primary Medical Reviewer Kathleen Romito, MD - Family Medicine
Primary Medical Reviewer Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer Christopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology
Last Revised August 5, 2011

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