Shaping Restored Vision on a Corneal Lathe : Surgical Procedure Said to Pick Up Where Radial Keratotomy Leaves Off

Before Peggy Lindauer received her first pair of glasses in the third grade, she was so nearsighted she couldn’t see the blackboard. She was, she recalled, “blind as a bat.”

In fact, the 23-year-old architectural draftsman has been so severely myopic all her life that she wouldn’t go swimming in the ocean alone because she was afraid she wouldn’t be able to find her way back to her beach towel without her glasses.

Contacts a Nuisance

She tried contact lenses two years ago but found they were a nuisance to wear and gave her even more eye strain.

Because of her severe nearsightedness, Lindauer was not considered a good candidate for radial keratotomy, the highly publicized and controversial procedure in which the cornea--the eye’s outer lens--is flattened by a series of microscopic incisions to bring the nearsighted eye back to normal vision.

Today, however, Lindauer said her vision is near normal, having gone from 5/800 to about 20/40.

The Stanton resident is one of a small number of Southern Californians who have undergone a surgical procedure that is said to pick up where radial keratotomy leaves off. (Radial keratotomy is designed primarily for people with mild to moderate degrees of nearsightedness and cannot be used on farsighted patients.)

The operation that Lindauer underwent earlier this year is called myopic keratomileusis for nearsighted people and hyperopic keratomileusis for farsighted people.

‘Living’ Contact Lens

Performed under local anesthesia on an outpatient basis, the 30- to 40-minute operation involves removing a microthin slice of the patient’s cornea, reshaping it with a special lathe and reattaching it to the patient’s eye.

The patient’s own cornea, in effect, becomes a “living” contact lens.

Dr. Walter Stark, professor of ophthalmology at Johns Hopkins--Wilmer Eye Institute in Baltimore, Md., emphasized that surgical procedures designed to correct nearsightedness are all “considered investigational and they are being evaluated to determine their long-term safety and effectiveness.

“One of the problems when you’re dealing with something like nearsightedness, which is not a disease but a variant of normal,” he said, “is that one has to look closely at the risk-benefit ratio, and it’s difficult to recommend a procedure that can be complicated by decreased sight and, in some cases serious complications such as blindness, when there are satisfactory alternatives such as glasses or contact lenses.”

Stark, a member of the ophthalmic device section of the Food and Drug Administration, said that myopic and hyperopic keratomileusis “are the most investigational of the refractive corneal surgery procedures. Only a small number of cases have been performed in the United States and there is no long-term follow up on any significant number of patients that would support the safety and effectiveness of this procedure.

“And I would say, as with any of the surgical procedures to correct nearsightedness, the patient should be fully informed of the possible risk of that surgery and the knowledge that there is no long-term follow up,” he continued. “In effect, no one knows what is going to happen five, 10 or 20 years down the line. They should undergo this procedure only after careful consideration of those risks and a complete trial of all alternatives, which include glasses and contact lenses.”

With keratomileusis procedures, he added, “there appears to be an interface problem (scarring between the areas of the corneal cut) and this leads in a high percentage of cases to some reduction of vision.”

There are about a half-dozen lathes used for keratomileusis surgery in Southern California, including several in the Los Angeles area, but only a few surgeons have done “consistent numbers” of cases, according to Milton Weinberg, president of Steinway Instrument Co. of San Diego, which manufactures the lathe.

In the year since the Medical Center of Garden Grove purchased the $65,000 lathe, Dr. Robert Fenzl, an ophthalmic surgeon and co-director of the Orange County Eye Surgical Center in Garden Grove, has performed the operation on about three dozen patients, including Lindauer.

“The procedure,” Fenzl said, “is mainly for people with moderately high to high degrees of nearsightedness, especially those out of the range of radial keratotomy, and for people with moderate to high degrees of farsightedness for which there is no other useful surgical procedure.”

Fenzl said most of his patients who undergo the procedure have problems wearing contact lenses.

“People who are extremely myopic can’t wear contacts because of the thick edges and it’s hard to get the lenses to center on the eye,” he said. “And many people are sensitive to the lenses or they become allergic to the preservatives in the (lens) solution.”

Other patients, Fenzl said, are tired of the “disability” of having to wear glasses, which prevents many from participating in swimming or other activities.

Fenzl, who has performed radial keratotomy on more than 3,500 patients over the past six years, says that after undergoing RK “about 95% of the patients see 20/40 or better--you need 20/50 in California to drive a car without glasses.”

20/40 or Better

With the MKM and HKM procedure, he said, about 85% of the patients end up seeing 20/40 or better without correction. And, he said, the vision of the other 15% is “much improved,” although it is less than 20/40.

Said Walter Stark of Johns Hopkins: “I don’t think that’s been shown. Those results have not been published to support this.”

The procedure was developed in Bogota, Colombia, in 1963, but was not introduced in the United States until 1979. Since then, about 2,000 Americans have undergone the operation.

About 1,000 of those patients were operated on by Dr. Lee Nordan, a La Jolla ophthalmologist and corneal specialist who has been performing keratomileusis surgery since 1979.

Nordan, an assistant clinical professor at the Jules Stein Eye Institute at UCLA, emphasized that it is important to put keratomileusis and radial keratotomy in perspective.

“When radial keratotomy came out, eye surgeons were thinking this could be used for all kinds of myopias,” he said. “They tried it and were doing it on some cases that just exceeded the capacity of radial keratotomy to correct. In moderate amounts of nearsightedness, radial keratotomy works well. When RK is not able to be effective you progress to the next stronger thing: keratomileusis. It’s a judgment for each individual patient.”

The problem for patients, however, may be in finding an ophthalmic surgeon trained to do the procedure. Nordan said there are only 15 surgeons in the United States and about 20 in the world trained to do it.

Difficult Operation

“It’s probably the single most difficult operation in ophthalmology,” said Nordan, who trained most of the U.S. surgeons who perform the procedure. “The reason it is (difficult) is that it’s using very technical machinery. The machine is really a lathe that works to an accuracy of about one three-thousandth of an inch. You’ve become a machinist and most surgeons are not comfortable becoming a machinist. As a surgeon, you have to feel comfortable with the technical side of it as well as the surgical side of it.”

For that reason, Nordan doesn’t anticipate the number of surgeons performing the procedure to increase greatly in the future.

“I think unfortunately this procedure is so difficult to master,” he said, “that there may be an increased awareness of the procedure, but I don’t think it will ever be widespread for most doctors to perform this operation.”

Fenzl explained that the operation is performed on only one eye at a time. A local anesthetic is used to numb the nerves, including the optic nerve, so that the eye doesn’t move and there is no pain.

Pre-operative data--including the curvature of the cornea, how much correction is required, the pressure of the eye and age of the patient--is fed into a computer, which determines how much change in the shape of the cornea is necessary.

In the operation, a microthin slice of the patient’s cornea is removed with a Microkeratome (an instrument that is likened to a motorized carpenter’s plane) and frozen with a liquid gas. Fenzl explained that “the (corneal) tissue has the consistency of a wet noodle when removed, so it is frozen in order to make it hard so it can be carved like a contact lens is.”

After the tissue is frozen, the surgeon uses the lathe to carve out a hollow on the back surface of the tissue, a procedure that takes only about 1 1/2 to 2 1/2 minutes.

The reshaped cornea is then thawed and reattached to the patient’s eye with one continuous suture that resembles an eight-pointed star.

The patient’s eyelids are lightly sutured together for two days to prevent irritation caused by blinking.

Usually there isn’t marked improvement until the sutures are removed from the cornea in 10 days or two weeks, although total visual improvement may take up to two months.

After the eye heals and vision returns, the other eye is operated on four to 12 weeks later.

The cost is about $3,500 per eye, according to Fenzl, who said some insurance policies exclude refractive surgeries (operations that change the power of the eye) from coverage. He added, however, that “most policies cover this procedure because there is little doubt the people have a disability.”

Fenzl said there is no problem with the eye rejecting the re-shaped corneal tissue “because we’re only transplanting the building blocks and not the living cells and the body only rejects the living cells.”

As with any surgery, Fenzl said there is a certain amount of risk. “Like any other surgery on the body, the body is always opened up to infection or poor scar formation though the incidence of these is extremely low.”

There is also the possibility that the corneal tissue may crack during the freezing process, he said. “If there’s any irregularity (in the patient’s cornea) or problems during the procedure, we always have a donor cornea available as a backup.”

Although donor corneas are available, Stark added, “when you use a donor cornea, you begin to run the risk of rejection of that foreign donor material and that can lead to blindness and the need for a corneal transplant.”

Saying the surgery is “not perfect” but “it’s a very good attempt,” Nordan noted that “the biggest problem you get is if the surface of the eye heals with an irregular, wavy surface. In one out of 20 cases that might happen. If that happens you need a contact (lens) to smooth that out, or we can re-do it” with a donor cornea.