On the horizon: New solutions for vision defects
August 27, 1999
Web posted at: 11:09 a.m. EDT (1509 GMT)
From Kathleen Doheny
Special to CNN Interactive
(CNN) -- The prediction is echoed among eye surgeons: Contact lenses and eyeglasses will soon be obsolete, thanks to better surgical solutions for nearsightedness, farsightedness and other vision problems.
"Within a decade, we'll have a (surgical) solution for everyone,'' says Dr. Doyle Stulting, professor of ophthalmology and director of the cornea service at Emory University School of Medicine, Atlanta, and a member
of the refractive special interest group for the American Society of Cataract and Refractive Surgery. "Surgery will become the preferred method for (correcting) refractive errors.''
Some may disagree, including those who lack the financial resources for the often-pricey surgeries, as well as those too squeamish to undergo elective eye surgery.
But one thing's certain: Plenty of new options to correct vision problems are in the pipeline, both for refractive errors and conditions such as cataracts, when the natural transparency of the eye's lens becomes cloudy.
For years, people who wear contact lenses have complained about the constant need for cleaning and replacement. Why not just implant a lens and be done with it?
That might soon be possible. Under study by STAAR Surgical Co. of Monrovia, California, is the Implantable Contact Lens, or ICL, to correct nearsightedness, farsightedness and astigmatism, says Bob Anello, a company spokesman.
Two weeks before this intraocular lens is placed, the surgeon makes a tiny opening of about a half-millimeter in the periphery of the iris. Then, with the eye numbed by topical anesthetic drops, the ICL with the custom prescription is inserted (while folded) and then positioned into place behind the iris.
It's similar to lenses put in after cataract surgery. But with cataract patients, the degenerated lens is removed. In the case of ICLs, the eye's natural lens is left in place, and the ICL corrects vision in much the same way as a contact lens.
"It can be reversed, and it doesn't change the structure of the eye in a permanent fashion,'' says Dr. John Vukich, a clinical investigator for the lenses and medical director at the Davis Duehr Dean ophthalmology center in Madison, Wisconsin.
According to Vukich, the lens can correct up to -20 diopters of nearsightedness and 10 of farsightedness. Clinical studies for farsightedness and nearsightedness are underway, and a study for farsightedness or nearsightedness with astigmatism is expected to begin later this year.
It would be possible to have a monovision prescription, correcting one eye for distance and one for near in patients with presbyopia, the age-related decline in focusing ability.
The ICL could be available by 2002, and similar lenses are under study by other companies.
"I think phakic IOLs (intraocular lenses) will be big for high degrees of myopia,'' says Dr. Marguerite McDonald, a New Orleans ophthalmologist specializing in refractive surgery and a clinical professor at Tulane University.
Under study for low to moderate farsightedness is a technique called radiofrequency thermokeratoplasty, in which radio-frequency energy heats and shrinks the cornea to reshape it and correct the vision problem. The procedure takes about five minutes per eye, depending on the amount of correction needed.
The technique is in the third phase of clinical trials, says Mitch Campbell, president of Refractec Inc. in Laguna Hills, California, which markets the Refractec Corneal Shaping System. Clinical trials of the technique are underway, and it could be available by 2001. The technique might also prove useful for eyes overcorrected by excimer laser surgery and for presbyopia and astigmatism, Campbell says.
Also under study is laser thermal keratoplasty by Sunrise Technologies International of Fremont, California, which shrinks the collagen in the mid-periphery of the cornea to achieve vision correction in a matter of seconds. It is designed to remedy farsightedness from .75 to 2.5 diopters, says Ed Coghlan, a company spokesman.
In late July, the Food and Drug Administration's Ophthalmic Devices Panel did not recommend approval for the Sunrise LTK laser system but recommended that the company provide additional data. Sunrise plans to pursue steps for approval.
One concern about keratoplastic procedures has been that the effect slowly subsides after a few years. McDonald doesn't see this as a problem, at least not for everyone. "There is a place in refractive surgery for a quick and easy and cheap procedure that can be repeated every few years,'' she says; it will give people a chance to try out the technique.
For years, doctors have corrected presbyopia, the loss of ability to focus on near objects that occurs with age, by prescribing bifocal eyeglasses, bifocal contact lenses or monovision contact lenses (correcting one eye for distance, the other for near). But the solutions are far from perfect.
Under study by C & C Vision, Aliso Viejo, California, is an accommodating/refractive lens, permanently implanted in the eye after the eye's natural lens is first removed during a 20-minute procedure with local anesthetic. The new lens corrects distance vision and restores the ability
to focus at all distances. "The lens moves backwards and forwards along the axis of the eye when the patient decides to change focus, simulating the focusing ability of a young person,'' says J. Andy Corley, C & C's CEO.
The lens is based on the theory, long held, that presbyopia occurs when the lens becomes stiff and the ciliary muscles (whose main job is helping the eye see at different distances) can't move the lens as well. The company hopes to start clinical trials in the United States this year, and the lens could be on the market within three years.
Another approach, called Surgical Reversal of Presbyopia, or SRP, is under study by Presby Corp. in Dallas, Texas. During a 30-minute procedure with local anesthetic, four tiny segments, made of the same plastic used in intraocular lenses implanted after cataract surgery, are implanted in the sclera (the eye's white outer coat) above the ciliary muscles, says Mark Cox, CFO of Presby Corp.
This method is based on a new theory that presbyopia occurs because the lens continues to grow throughout life, crowding the ciliary muscles. This crowding is thought to loosen the fibers connecting the ciliary muscles to the lens, making focusing at near distances more difficult.
After the segments are implanted, the sclera is expanded, remedying the crowding of the muscles and allowing the fibers to tighten again and the ciliary muscles to work better, says Dr. Robert Marmer, an Atlanta ophthalmologist and clinical professor of surgery at Morehouse School of Medicine who is familiar with the approach.
Clinical trials are expected to begin in October, and SRP could be available by 2003.
Which theory is correct? "There is some data to support both theories,'' says Stulting of Emory, who advises his colleagues to keep an open mind.
Cataract removal is already safe and efficient. But it soon could become even better.
Currently, most cataract surgeries are done with a process called phacoemulsification. After the surgeon makes a small incision in the eye, he uses an ultrasonic, oscillating probe, which fragments the hard center of the cloudy lens and also suctions the cataract fragments from the eye.
Now there is a prototype device called Catarex, which removes the cataract by using a high-speed propeller-like device rotating 70,000 revolutions per minute to break up and remove the cataract from the eye. Clinical studies could begin in 2000, says Dr. A. Joseph Rudick, president of Atlantic Pharmaceuticals Inc. Bausch & Lomb signed a licensing agreement with Atlantic for the device.
In clinical studies is the Photon laser cataract removal system. While many people think lasers are used now for cataract removal, they are not. (Sometimes a surgeon will use a laser after the original surgery if the back membrane of the eye turns cloudy.) The new laser uses a fiber optic probe instead of ultrasound, says Robert Millar, spokesman for Paradigm Medical Industries Inc., in West Valley City, Utah, the laser manufacturer.
One advantage of the new system, he says, is that patients regain visual acuity somewhat more quickly than they do after the phacoemulsification technique.
Both new approaches will make it possible for the surgeon to make an even smaller incision to remove the cataract than is made with current methods, says Dr. Samuel Masket, an ophthalmologist in West Hills, California, and clinical professor of ophthalmology at the UCLA Center for Health Sciences.
As exciting as some of the new techniques might sound, some may not make it to market, derailed by unexpected complications such as a lack of research and development funds, or a lack of government approval.
Even the techniques that do become available won't be right for everyone. There is no one-size-fits-all solution because vision problems vary from person to person.
A surgery that works well for one person might produce less than desirable results for another. Recently, U.S. Representative Rick Hill (R-Montana) announced he will step down due to vision problems after RK (radial keratotomy). He plans to undergo some corrective procedures soon, says Andy Hallmark, a Hill spokesman. But the vision defects that followed the surgery made it very difficult to keep up with the demands of the job, Hallmark says, including volumes of reading related to legislation.
Before undergoing surgeries -- either those available now or those on the horizon -- consumers should find out if there are any occupational bans on the procedure that might affect their plans.
Some branches of the military, for instance, take a dim view of their members having refractive surgery, sometimes banning it altogether. The Army won't allow someone who has had refractive surgery to be a pilot, for instance, says Russ Oaks, a spokesman.
As of July, the Air Force policy is not to accept anyone who has had LASIK (laser assisted in-situ keratomileusis) or RK, says Betty Anne Mauger, a spokeswoman. The concern is that LASIK is still relatively new and that RK might weaken the cornea, she says. Air Force personnel who want to undergo PRK (photorefractive keratectomy) can apply for a medical waiver.
Navy policy is under review, says Capt. Ryland Dodge, a spokesman. Some Navy personnel can apply for a waiver, he says, with PRK the most likely to get the waiver. Navy personnel in warfare specialties such as divers, pilots and SEALs cannot apply for such waivers, Dodge says.
The Marines don't accept new recruits who have undergone refractive surgery, says Capt. Jeff Sammons, a spokesman.
As the newer eye surgeries and procedures become perfected, these occupational policies may become more lenient.
The caveat for consumers is to check out any possible obstacles well before signing the surgical consent form.