Nearsightedness surgery; Radial keratotomy; Corneal surgery
Corneal surgery corrects mild to moderate nearsightedness (myopia). Newer procedures are also available for farsightedness and astigmatism.
Topical anesthesia (numbing eye drops) is used. The ophthalmic surgeon may use an instrument called a keratome to lift a flap of tissue from the surface of the cornea. Then a laser is used to re-shape the surface of the cornea and the flap is replaced into the original position.
The procedure is usually painless and the improvement in unaided vision is usually immediate. The patient can quickly return to most activities, but must avoid bumping the eye or submerging in water (swimming, for example) to avoid dislodging the flap.
This method of refractive surgery offers fewer side effects compared to radial keratotomy, which was common in the 1980’s. Usually both eyes are done in the same session.
The guideline for refractive surgery is the desire to treat nearsightedness so corrective lenses will no longer be necessary. Most forms of nearsightedness can be reliably corrected.
General anesthesia is not used. The cornea has no blood vessels and bleeding does not occur.
However, after surgery some patients experience the following symptoms:
- fluctuating vision, including halos around lights.
- under-correction or over-correction
- infections of the cornea which can result in permanent vision loss (unusual)
- scar of the flap incision which can result in permanent vision loss (unusual)
- difficulty seeing at night due to glare (light sensitivity)
- dislodgement of the flap, even long after surgery
Expectations after surgery
Long-range follow-up studies of people who have had the procedure indicate that nearly 90% will see close to 20/20 without glasses. Approximately 10% reported partially corrected vision with a continuing need for glasses or contact lenses. One percent experienced serious complications which permanently decreased the vision.
For those older patients who needed bifocals before surgery, reading glasses will still be needed even though distance vision may be clear without glasses.
The procedure is done on an outpatient basis. It takes only a short time, with the person under local anesthesia. Protective glasses may be worn for several days, although full recovery can take several months.
by Janet G. Derge, M.D.