CLE VS. LASIK
Once patients reach their 40s, lens exchange has distinct advantages.
BY LOUIS PILLA

Despite advances in LASIK, it may not be the most appropriate procedure for all of your patients who want refractive surgery. That's especially the case for older patients who are highly myopic or hyperopic.

Clear lens exchange (CLE) represents one increasingly popular alternative to LASIK for these patients. In this article, we'll discuss the procedure, evaluate how it compares with LASIK, and offer clinical pearls. First, though, let's take a look at some numbers.

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Acceptance on the Rise

Surgeons are slowly adopting CLE, suggest statistics from the American Society of Cataract and Refractive Surgery (ASCRS). A 1999 study found that 11% of surveyed members on average performed one to two clear lens exchange procedures per month. That number grew to 16% in a 2000 survey and to 19% in 2001. (See "Tracking the Growth in CLE," on the next page.)

Clear lens exchange, says Kurt Buzard, M.D., F.A.C.S., Buzard Eye Institute, Las Vegas, Nev., "rightly deserves to be considered high on the list of surgeries when we're performing surgery in patients who are in their late 40s and early 50s. I believe that in the next five years, we'll see a gradual reduction in corneal refractive surgery to the benefit of lens-based refractive surgery in all age groups," he says.

Who Benefits Most

One main reason for considering CLE instead of LASIK is optical quality. IOLs provide better optical quality for higher corrections, says Jonathan M. Davidorf, M.D., Davidorf Eye Group, West Hills, Calif. And, according to Pit Gills, M.D., St. Luke's Cataract and Laser Institute, Tarpon Springs, Fla., with LASIK, you turn a prolate cornea into an oblate cornea. That means even patients who fall within LASIK parameters -- especially high myopes -- find that the quality is better with CLE than with LASIK.

James P. Gills, M.D., founder and director of St. Luke's, offers CLE to patients who are younger than 45 and are high myopes or hyperopes. He recommends it to all refractive surgery candidates older than 50 -- even if they fall within LASIK parameters. Patients with high levels of myopia or hyperopia, he notes, are functionally disabled and benefit the most from CLE. Age 45 to 50 represents a good median age for considering the procedure, he suggests.

For hyperopia, "there's no question that lens exchange is the procedure of choice," says Dr. Buzard. And, he continues, that probably would be the case in young patients if their lens didn't have to be removed. The lens, he notes, frequently causes hyperopia. That means if you correct one diopter of hyperopia at age 50 using refractive surgery, you may well have to correct another diopter in 3 to 5 years -- an unattractive option.

Because of thin corneas, surgeons typically will consider a lens procedure as opposed to LASIK with patients who are past +3D, says R. Bruce Wallace III, M.D., F.A.C.S., Wallace Eye Surgery, Alexandria, La. The need to remove more tissue may take LASIK outside the realm of a surgeon's comfort level, says Wallace, who is also clinical professor of ophthalmology at Louisiana State University in New Orleans. What's more, LASIK for these patients, which involves a doughnut-shaped ablation deep in the cornea's center, can result in problems such as glare and regression over time, says Dr. Buzard.

When presbyopia is part of the picture, CLE emerges as a very attractive alternative to LASIK. For example, Dr. Pit Gills recommends that a 45-year-old presbyopic patient who is also a -7D or -8D myope have CLE. The hyperopic presbyope over age 50 presents an ideal CLE patient as well, says Dr. Wallace. These patients tend to be more disabled than myopic patients, having no good vision either near or at distance without glasses. What's more, their vision is likely to get worse.

LASIK Shortcomings

If LASIK were risk-free, surgeons might not consider CLE as an alternative for older patients. But corneal laser surgery isn't an innocuous procedure. Neither, of course, is CLE, but when the two options are considered side-by-side for this age group, CLE often makes more sense.

Besides the reasons touched on earlier, a refractive procedure might not account for problems found in the lens. For instance, astigmatism and higher-order aberrations are normally found in the cornea, says Dr. Buzard. As patients age and begin to develop lens changes, higher-order aberrations, particularly astigmatism, reside in the lens. That means if you perform surgery on the cornea and then remove the lens, you'll need to perform yet another surgery to account for the lens changes.

What's more, LASIK can add to loss of contrast. If you have a LASIK procedure along with, say, a 1-plus nuclear change in a lens, "the combination of contrast loss is enough to make very dissatisfied patients," says Dr. Buzard. "When that lens is removed, patients are exceedingly pleased. They see a return of that bright, contrasty world. And that's a serious issue."

Dr. Buzard ticks down a list of additional problems that make CLE a better choice for older patients:

Diminished corneal wound healing. Dr. Buzard has seen an increase in epithelial ingrowth between the flap and the bed in patients age 50 and older because these patients don't heal as well. As patients reach their mid 50s and certainly their 60s and 70s, they deserve "careful consideration of lens-based refractive surgery rather than simply trying to apply a technology that was really designed for a younger patient with better wound healing," he notes.

Epithelial disruption during the microkeratome pass. In the 50s, the epithelium seems to become less well-adhered, he says. Even without clinical evidence of map-dot-fingerprint dystrophy or epithelial adherence problems, when you make the microkeratome pass, older patients more frequently suffer an abrasion than younger patients.

In the past, this was thought to be inconsequential and simply part of LASIK, but in fact it has "dire consequences in some patients," he says. The patient can have months of diminished vision because the epithelium takes a longer time to remodel (or may, in some patients, never remodel). Epithelial erosion, he says, frequently leads to diffuse interstitial lamellar keratitis (or Sands of the Sahara syndrome).

Dry eye. Of course, prolonged dryness can lead to diminished vision.

Autoimmune disease. Older patients may have some mild form of autoimmune disease, such as rheumatoid arthritis. This can contribute to problems such as flap melting.

Assessing the Risks of CLE

CLE also carries risks, including endophthalmitis, retinal detachment and macular edema. "These are real concerns," says Dr. Wallace, but he notes that vast improvements in procedures have been made. Here's what surgeons had to say about possible complications:

Endophthalmitis. The incidence of endophthalmitis is 1 in 20,000 in the practice of Drs. Pit and James Gills. In a 3-year study he just concluded, Dr. Buzard says he found no endophthalmitis in 5,000 patients. To prevent it, he uses such techniques as careful draping, povidone-iodine, and subjunctival injection of antibiotics over the incision area. He also uses a blueline incision because of better healing. Surgeons, he says, who use blueline incisions or have some blood involved with their limbal incisions won't have as many infections as those who use clear corneal incisions that aren't adequately sealed. In addition, says Dr. Wallace, the soon-to-be available new antibiotics should help further reduce post-op infection.

Retinal detachment. The risk of retinal detachment, notes Dr. Buzard, is the same for patients with lens-based refractive surgery as for patients who haven't had the procedure. Dr. Pit Gills notes that in a series of nearly 1,000 of their CLE patients (many of whom were high-risk eyes), there have been only three retinal detachments. Surgeons considering CLE, says Dr. James Gills, should have a vitreous loss incidence of 1 in 500 cases or less.

High myopes with no posterior vitreous detachment are most at risk for retinal detachment because the vitreous is still engaged with the retina, notes Dr. Wallace. He would send those and other high-risk patients to a retinal surgeon for evaluation before performing CLE and follow the patient closely after the procedure.

PCO. While 30% to 40% of patients get posterior capsule opacification (PCO) after cataract surgery, CLE patients get PCO more often, estimates Dr. Pit Gills. But a YAG laser offers a straightforward, safe procedure to address this condition.

Photopsia. Some patients with certain IOL models will complain of photopsia. However, this was more common with older-model acrylic lenses. It's less of a problem now, Dr. Davidorf says.

Like a laser surgery patient, a CLE patient could require an enhancement. That will likely entail a laser refractive procedure to obtain a small correction, notes Dr. Davidorf. He informs his patients that there's a 10% to 15% chance they'll require a laser procedure after CLE.

An IOL exchange is another option. In those cases, Dr. Buzard uses hydrodissection with viscoelastic to break the capsule open, move the lens out, cut it in half, take it out through the original incision and put a new lens in. If he can't exchange the lens, he'll insert a piggyback lens.

Refractive Cataract Surgery is a "Natural Evolution"

For patients with evidence of a cataract, Dr. Davidorf leans toward CLE instead of a laser refractive procedure. For one thing, a laser refractive procedure can, he notes, make a visually insignificant cataract significant. This can result in a huge patient management problem as you try to determine whether a visual aberration is laser-related or involves a cataract. What's more, consider the impact of laser surgery on IOL power calculations, he notes. With CLE, IOL calculations should be more precise and maintain the cornea's pristine quality.

Of course, CLE eliminates the need for future cataract surgery, which can be a near-term possibility for older patients. In fact, patients over 50 may have some lens change and even early cataract, notes Dr. Wallace. CLE, he suggests, may be a misleading designation for those procedures because many of these lenses are not "clear." "Refractive cataract surgery is the natural evolution of cataract surgery," he says. "While you have the patient anesthetized and the eye sterile, why not provide refractive surgery?"

As for astigmatism, toric IOLs represent one option, says Dr. Buzard. He has also developed a way to make relaxing incisions at the slit lamp.

Get Ready for the Future

Some 5% to 10% of Dr. Davidorf's refractive practice consists of CLE cases. That percentage hasn't increased much, he says, during the past few years. One thing that would increase it, he says: a true accommodating IOL.

Still, if cataract surgery is part of your practice, you'll want to hone your skills to perform CLE, suggests Dr. Wallace. For instance, look for ways to improve your IOL calculation accuracy before adding refractive lens exchange.

The world of refractive surgery, notes Dr. Buzard, is moving toward the lens. You'll do well to keep up with CLE to make sure that the world doesn't move ahead without you.

Pilla (pilla@netreach.net) is a freelance healthcare journalist based near Philadelphia, Pa.