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.
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
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
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
Complications of corneal ring implants may
- Glare or
- Night vision problems.
- Overcorrection or
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
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.
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.
|Primary Medical Reviewer||Kathleen Romito, MD - Family Medicine|
|Specialist Medical Reviewer||Christopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology|
|Last Revised||June 24, 2011|