American Academy of Ophthalmology Web Site: www.aao.org
Focus On Clear Lens Exchange
The idea of clear lens exchange is gathering momentum as a viable solution for presbyopes without cataracts. But some physicians question whether their patients, and IOL technologies, are truly ready.
In 1976, the legendary rock group Jethro Tull sang about a man who is "too old to rock 'n roll, but he's too young to die." The millions of 20-somethings who listened to that song are now 50-somethings, and the lyrics have become an analogy for their vision dilemma: They are too old for laser surgery but too young for cataract surgery. Therein lies the rub, and the increasing consumer demand for clear lens exchange.
"Refractive lensectomy is definitely on the rise in this part of the country," noted Kerry D. Solomon, MD, professor of ophthalmology at the Medical University of South Carolina in Charleston. "People are more active later in life, and thus want to be spectacle-independent. And we are dealing with a different population than the previous generation. These 50-plus-year-olds were around for the LASIK boom, and now both individuals with cataracts and those not yet experiencing visually significant cataracts are seeking the same lifestyle vision."
The removal of a healthy crystalline lens for purely refractive purposes may be part of a larger social trend. From testosterone replacement to electively induced childbirth, a number of medical procedures are expanding from the strictly therapeutic to the cosmetic and the convenient.
But the pressure to provide elective procedures comes with myriad attendant questions: Is the very idea medically wise? In the case of clear lens exchange, which patients are good candidates? Which lenses should be considered? What are the potential complications?
Whether to Offer Clear Lens Exchange
The opinions of ophthalmologists span the spectrum from guarded skepticism to shrugging acceptance to outright enthusiasm. Some doctors think the timing is perfect to introduce patients to clear lens exchange, while others continue to take a wait-and-see approach.
Green light: go for it. Richard S. Hoffman, MD, clinical associate professor of ophthalmology at Oregon Health & Science University in Portland, is an enthusiastic supporter of clear lens exchange, also called refractive lensectomy. Dr. Hoffman and colleague I. Howard Fine, MD, were early adopters. "Dr. Fine was one of the original investigators of the Array multifocal lens, always thinking 10 years down the road," Dr. Hoffman observed. "However, the refractive lens exchange procedure didn't start becoming popular in the medical press until ReStor, ReZoom and Crystalens arrived on the scene. But we were getting results with the Array. Today, Dr. Fine and our group continue to advocate clear lens exchange to the ophthalmologic community as a viable refractive surgery modality."
Yellow light: wait a few years. Although he's not opposed in principle to clear lens exchange, Douglas D. Koch, MD, professor of ophthalmology at the Baylor College of Medicine in Houston, is waiting for a better accommodating intraocular lens, "And we may have one in the next five to six years. So if I can tide over patients who want refractive lens exchange for another few years, I try to do this. Refractive lens exchange closes the door to these upcoming options."
Red light: show me more progress. Carl V. Migliazzo, MD, in practice at the Kansas City Eye Clinic in Overland Park, Kan., takes a conservative approach to clear lens exchange, a position he has maintained since he was first interviewed by EyeNet on the same subject two years ago. As a general ophthalmologist who specializes in glaucoma and cataracts, he represents a voice for surgeons who are aware of the procedure but are not ready to endorse it. "I have not yet bought into clear lens exchange," said Dr. Migliazzo. "I am a conservative surgeon and continue to watch and wait. The surgical risk, the glares and halos at night, the 9 percent reported explantation rate in the initial studies, all of these factors are a concern for me. I even know colleagues who have tried the accommodative lenses and stopped doing refractive lens exchange altogether." Dr. Migliazzo added that the technology is "great" and moving in the right direction, and will only continue to improve. But for now, citing ties to the Show Me State, he says he will remain "sitting on the sidelines waiting for something better."
Green light: as green as it gets. H. L. "Rick" Milne, MD, president of The Eye Center in Columbia, S.C., is not among those sitting on the sidelines. He observed that there is a "definite market that will increase. More surgeons will offer the procedure and more patients will demand it." He noted that already a third of his cataract patients want the upgrade to the multifocal or accommodative lenses, and are not put off by the premium price. "While the $7,000 to $10,000 price tag does limit clientele," Dr. Milne said, "more and more people are willing to spend these dollars. It's a growth market." He attributed the popularity of refractive lensectomy to the fact that it represents a permanent solution. "You remove the part of the eye that will age, and the part of the eye that will cause presbyopia, so the patient will never get a cataract nor become progressively more presbyopic. Their eyes are receiving a permanent fix."
Who Are the Candidates?
The ideal patients for clear lens exchange? Dr. Solomon noted the ideal candidates are hyperopic, presbyopic patients, aged 50 to 55, with or without astigmatism, and with mild incipient cataracts.
"If we were to do a LASIK procedure on these patients, the long-term stability of their refraction may change over the next 10 years," he explained. "However, if the incipient cataract is removed, the quality of vision is probably as good as or better than with a wavefront optimized lens compared with a LASIK technique. Additionally, patients have the option of treating their presbyopia with a presbyopia-correcting IOL, something we can't currently offer with LASIK."
Some caveats. Dr. Koch restricts lens exchange to patients with early cataracts but will also operate on hyperopes when no other good option exists. "On the other hand," he said, "I might delay older high myopes with early signs of cataracts because they are good candidates for phakic IOLs. I would implant a phakic ICL [implantable contact lens] until an even better presbyopia-correcting lens is available." As a reason for this approach, Dr. Koch cited the high risk of retinal detachment in myopes - especially male myopes between the ages of 50 and 60 - that is associated with clear lens exchange.
D. Michael Colvard, MD, of Colvard Eye Center in Encino, Calif., participated in the early FDA trials of the Crystalens. He, like many surgeons, continues to take a conservative approach to the procedure. "This is an important part of the services that we provide patients, but I continue to think that we must be very careful in patient selection and only offer this modality to the best candidates," he said. Dr. Colvard bases patient selection on age and refractive error. An ideal patient is one who is over 40 years of age, contact lens intolerant and hyperopic with 3 or more diopters. Another group is older hyperopes, over age 55, who desire refractive surgery but who have early cataract changes. These individuals are not good LASIK candidates because they tend to experience problems with the tear film, they heal more slowly after keratorefractive surgery than younger patients and early cataract changes result in a reduction of visual quality following laser surgery.
Keep an eye on young, high myopes. Dr. Colvard has deep reservations concerning younger myopes because of the increased risk of retinal detachment. "The best prospective study looking at the incidence of retinal detachment after clear lens exchange was published in Ophthalmology a number of years ago," he said. "The incidence of detachment during the first seven years was 8 percent in high myopes. Those risks can be accepted if the patient must undergo cataract surgery, but for clear lens exchange, the risk-benefit ratio is not acceptable."1
Psycho-ophthalmology. While physicians all have their own set of patient selection guidelines, there is more to the process of considering patients than visual acuity and age. "The art of the procedure is picking the right patients because there is a certain percentage who won't be happy," said Dr. Hoffman, adding that the psychological component of patients seeking clear lens exchange cannot be ignored. "Truly, the first thing the ophthalmologist needs to determine is how compulsive and obsessive their patients are," he explained. "If they are very particular about their vision, they are not good candidates. If someone asks 100 questions preoperatively about halos, they will inevitably complain in 101 ways postoperatively on the nature of the halos."
In contrast, patients who are highly motivated, laid-back hyperopes who are willing to wear glasses part-time will make good candidates, Dr. Hoffman said. He added that low myopes are difficult to make happy because of the nature of their near and distance vision, and high myopes are good candidates "as long as they are aware of the increased risk of retinal detachment and are highly motivated."
Which Lens for Which Patient?
The next step in successful clear lens exchange is deciding on the IOL: the ReStor or ReZoom, which are multifocal lenses, or the Crystalens, an accommodative lens.
Weigh the refractive properties. Dr. Hoffman explained that the accommodative Crystalens does not produce optical aberrations. Consequently, those who do a lot of night driving and cannot tolerate halos around lights at night, or those people who had previous corneal surgery such as a cornea transplant or multiple radial keratotomies are better candidates for accommodative lenses. The multifocals can lead to increased aberrations in these patients who may already have multifocal corneas
Where does your patient need focus? In most other cases, Dr. Hoffman prefers implanting the multifocal lenses because they provide better up-close vision, and are preferable for patients who can tolerate halos, "which tend to improve with time," he noted. The ReStor and ReZoom each have their benefits and limitations. ReZoom provides distance, up-close and intermediate vision, but is weaker than the ReStor for up-close vision. On the other hand, ReStor provides distance and up-close vision, but is weaker than the ReZoom for intermediate. "So you have to figure out the patient's needs," he added. "Do they watch television and use the computer a lot, or do they spend most of their time in up-close activities such as knitting or reading?"
Pupils, too large and too small. Another aspect to investigate is pupil size, which is often a consideration when selecting which lens to choose for implantation. "People with very large pupils may not be candidates at all for clear lens exchange because of the risk of increased glare," Dr. Hoffman explained. Large pupils that do not constrict will not obtain good up-close vision with ReStor. Small pupils will not get the near vision with the ReZoom lens because of its bull's-eye design; if the pupil does not dilate enough to expose the near-dominant rings, the lens will not work well for up close. "However you can stretch the pupil with an argon or diode laser postoperatively to expose the near-dominant rings and improve near vision."
Two lenses: mix or match? One major debate that has flared among ophthalmologists is whether to implant the same kind of lens bilaterally or mix products and technologies between the two eyes. Dr. Milne is a staunch supporter of custom matching lenses on an as-needed basis. "When I perform a clear lens exchange, I place the ReZoom lens in the dominant eye," Dr. Milne explained. "Then I bring the patient in for a postoperative check two weeks later and observe limitations such as any visual tasks they are not able to do. We can then custom match an alternative lens."
He added that choosing lenses is not a cookie-cutter exercise, but an art. "A year and a half ago, I got hammered for my views on custom matching at the AAO meeting," Dr. Milne said. "Yet in Las Vegas, I spoke with many ophthalmologists who saw the wisdom in this approach, which was positively reported on at the ESCRS meeting and is now the way that many are doing it in Europe."
Dr. Solomon is one ophthalmologist who is not convinced that custom matching is the way to go. "Market research shows that most ophthalmologists don't mix technologies," he said, "and when we did our spotlight survey at the Las Vegas AAO meeting, 88 percent of the ophthalmologists present said they did not mix technologies. And the 12 percent who did only did it occasionally. The popularity of mixing and matching lenses is a big misconception perpetuated by the trade journals. Doctors who do not mix technologies should not feel pressure to start doing it, as they are well within the standard practice pattern of the vast majority of refractive cataract surgeons. Both matching presbyopic IOLs and mixing them each represent visual and functional compromises for our prospective patient. The art of presbyopia-correcting surgery is to have a good understanding of what these compromises are so that physicians and patients alike can better understand the associated benefits and compromises, permitting a better informed decision and ultimately, a happier, more functional patient."
What Are the Contraindications and Complications?
From a comorbidity perspective, Dr. Hoffman noted that well-controlled glaucoma without visual defects, or controlled diabetes with no retinopathy, are not contraindications for clear lens exchange. "However, someone with significant visual field changes, moderate macular degeneration, diabetic retinopathy or significant corneal endothelial dystrophy are not candidates for multifocal lenses. This is because with multifocal technology, not all of the light is focused on the retina. The loss of efficiency that results from multiple images focused in front of the retina may lead to unacceptable visual quality and perhaps frank dysfunctional vision in these patients. These problems may become even more exacerbated if the underlying pathologic process is progressive," he said.
Dr. Koch added that mild glaucoma is not a contraindication for clear lens exchange. However, his contraindications include clinically significant glaucoma or corneal disease and any retinal condition that can predispose to development of cystoid macular edema, such as epiretinal membranes and diabetes.
These patients require patience. There are a number of additional factors ophthalmologists should consider when deciding whether or not to perform clear lens exchange procedures. First, there is, without a doubt, more chair time involved with these patients. Dr. Milne actually has a separate questionnaire for individuals aged 50 or older requesting refractive surgery or other procedures. The survey is designed to help him determine the outcome the patient is trying to obtain, and whether the patient wants a permanent fix. "We can offer procedures such as CK or laser that cost less but are not permanent," he explained. "Clear lens exchange is twice as costly but is permanent. We must determine the patient's needs."
Billing correctly. From an ethical standpoint, the question of whether a patient is undergoing the procedure for cosmetic or therapeutic reasons can become problematic. Dr. Hoffman stressed that if the patient does not have a significant nuclear sclerotic cataract, the refractive lens exchange is, in actuality, an elective procedure. "If a doctor starts billing insurance in this situation, it is improper," he said. "Many of these patients have a little bit of nuclear sclerosis but see 20/25, and they don't have glare or decreased vision. This should not be considered cataract surgery. On the other hand, if a patient presents with significant cortical opacities, glare and refractive error, this can be billed as a cataract procedure. But there is definitely a gray zone with many patients. It is important that the doctor thoroughly documents that there is a complaint related to the patient's cataract if they choose to bill insurance for the procedure."
Anticipate a tune-up. Dr. Milne stressed that a good refractive surgeon who chooses to perform clear lens exchange must know postoperatively how to fine-tune the patient's vision, as 30 percent of patients undergoing this procedure experience a residual refractive error. They also should discuss enhancement costs with the patient prior to performing the clear lens exchange.
One option, but an irreversible one. Finally, the fact that this procedure is permanent is a double-edged sword.
On the one hand, clear lens exchange offers a permanent solution to presbyopia and possible future cataracts, and on the other it prevents patients from taking advantage of the newer lens technology that some say will be available within the next decade.
Dr. Colvard noted that "nothing in our field remains static. Innovation will continue and future technologies will bring better opportunities for our patients. The lenses we have today are good, but the IOLs of the future, which are sure to provide stronger accommodation and improved quality of vision, will be better. Baby Boomers without lens opacification who simply want correction of presbyopia, especially those with low levels of refractive error, may want to wait until these technologies evolve."
But Dr. Hoffman said that his clear lens exchange patients are very happy with the current technology. He cited a 41-year-old high hyperope he treated five years ago with the Array lens, and she is pleased with her 20/20 vision and the fact that she will be spectacle-independent for the rest of her life. "There is always something better down the road, but why wait until you are 95 to try the latest technology? There are some excellent alternatives right now."
And some old Jethro Tull fans may just take him up on that.
1 Colin J. et al. Ophthalmology 1999;106(12):2281-2284.