Radial keratotomy (RK) for nearsightedness
Surgery Overview
Radial keratotomy (RK) involves making tiny cuts in the cornea, which flatten it and reduce nearsightedness. In people who have both astigmatism and nearsightedness, the surgeon may make additional cuts to flatten the misshapen part of the cornea that is causing the astigmatism.
Because the outcome of surgery on the first eye may affect how surgery is done on the second eye, many surgeons wait 6 weeks before treating the second eye. This delay also reduces the risk of spreading a corneal infection to the second eye. While waiting for the second procedure, you are usually fitted with a contact lens for the eye that is still nearsighted, since wearing two very different eyeglass prescriptions causes distorted vision.
What To Expect After Surgery
RK is an outpatient procedure. It is done under local anesthesia in a surgeon's office or a same-day surgery centre. The operation on one eye takes about 10 to 15 minutes, and the entire process usually takes less than 2 hours, including preparation time, care right after the surgery, and paperwork.
After surgery, you may wear a patch or contact lens on the eye and 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.
- Recovery is usually quick, with only mild discomfort. You may return to your normal activities within a few days.
- Some people may have pain, aching or throbbing, or a feeling that there is something in the eye for 24 to 48 hours after surgery.
- Your vision may remain blurry for days to weeks after surgery. Do not drive until your vision has cleared.
- For 2 weeks after surgery, avoid vigorous sports, eye makeup, and activities that may get water in the eye. The surgeon may recommend that you shower before the surgery and then avoid showering for a day or two afterward to keep from getting water in the eye.
Unstable vision is common in the first 3 months after surgery and may last for up to 1 year. Your vision may vary slightly over the course of a day (although not to the point that you would need two pairs of glasses).
Why It Is Done
Radial keratotomy is an elective, cosmetic procedure that is done to correct nearsightedness in otherwise healthy eyes.
Good candidates for RK have normal, healthy eyes with stable, mild to moderate nearsightedness (up to about 3 dioptres) that is not getting worse with time. RK may also correct some amount of astigmatism.
You may not be eligible for RK if you have:
- Nearsightedness that is still getting worse (such as in children and teenagers).
- Pathological myopia, in which the eyeball fails to stop growing longer.
- Degenerative changes caused by severe nearsightedness (high myopia), such as retinal tears.
- An abnormality or disease of the cornea.
- A connective tissue disease that might influence the healing of the cornea or that requires you to take steroids.
- A job or hobby for which the possible side effects of RK would be a problem. Glare is sometimes a side effect of the surgery, which would be a problem for a truck driver, for example. People who participate in activities such as contact sports that carry a high risk of eye or head injury may not be good candidates for RK, because a blow to the eye in someone who has had RK very rarely may cause the tiny incisions to rupture.
How Well It Works
RK is effective in reducing mild to moderate nearsightedness. It does not always completely eliminate nearsightedness. You may still need to wear corrective lenses some of the time for either near or distance vision (or both) after surgery. People who have moderate to high nearsightedness before surgery are more likely to still need correction for distance vision after surgery than those who are only mildly nearsighted.
The greatest problems with RK surgery are that the results are hard to predict and they tend to change over time. RK reduces nearsightedness, but it often causes mild farsightedness (overcorrection) or does not completely correct nearsightedness (undercorrection). Results are sometimes several dioptres different than predicted. In contrast, eyeglasses and contact lenses are fitted with an accuracy of within 0.5 dioptre of the desired correction.
The vision correction after RK also may be unstable. Most people who have RK surgery gradually become more farsighted for at least 8 to 10 years after surgery. This is called the hyperopic shift.
Risks
The most frequent complications of RK include overcorrection (farsighted after surgery), undercorrection (still nearsighted after surgery), and unstable vision (hyperopic shift). Retreatment is sometimes desired to correct these problems. You may not be able to wear contact lenses because of the shape of the eye after surgery. This is not the case with LASIK or PRK.
Complications can occur but are not common. These include:
- A loss in best corrected vision. Before RK, most eyes can be corrected with glasses or contacts to 20/20 vision or better. Up to 3% of people who have RK have best corrected vision of less than 20/20 after surgery.1 But the vision loss is usually not severe.
- Irregular astigmatism that causes ghost images or double vision.
- Double vision, difficulty seeing how objects are oriented relative to each other, or loss of fine depth perception.
- Glare, especially at night. Glare is common in the first 3 months after surgery and may last longer than 6 months. It does not appear to be a significant problem, but you may see halos or radiating lines around headlights or street lamps, and it may be harder for you to drive at night. Some people have reported that they need to wear sunglasses or change jobs because of glare.
A few very rare complications may threaten vision, including:
- Puncture (perforation) of the cornea.
- Infection of the cornea (bacterial keratitis). This may occur immediately after the surgery or up to 1 to 3 years later as the cornea continues to heal.
- Rupture of the cornea at the keratotomy scars after a severe blow to the eye.
- Glaucoma.
Radial keratotomy is considered safe. No deaths have been reported as a result of the operation, and serious complications are rare. But the procedure may have long-term side effects or complications that we do not yet know about.
What To Think About
If you are considering having surgery to improve nearsightedness, consider the different options (radial keratotomy, PRK, LASIK, corneal ring implants, and intraocular lens implants), and talk about them with your doctor. PRK and LASIK surgery have replaced radial keratotomy (RK) as the refractive surgeries chosen by most people, but RK is still very effective for mild nearsightedness (up to 3 dioptres) and in other cases. Corneal ring implants are a relatively new procedure for low levels of nearsightedness.
If you need another type of eye surgery later in life, such as cataract removal, the corneal scars from RK may make the operation and recovery more difficult. RK weakens the cornea, making it more prone to injury.
The RK surgery is a cosmetic procedure. The cost of refractive surgery varies in different locations, but it can be a significant expense. Provincial health plans and most private health insurance plans do not cover the cost of refractive surgery.
Complete the surgery information form (PDF)
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| Author: | Robin Parks, MS | Last Updated: August 22, 2007 |
| Medical Review: | Kathleen Romito, MD - Family Medicine Carol L. Karp, MD - Ophthalmology Andrew Swan, MD, CCFP, FCFP - Family Medicine | |
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| Topic Contents | |
| Surgery Overview | |
| What To Expect After Surgery | |
| Why It Is Done | |
| How Well It Works | |
| Risks | |
| What To Think About | |
| References | |