Getting Clear On Refractive Lens Exchange

This article is from April 2011 and may contain outdated material.

Patients with incipient cataract, significant refractive error, a desire for reduced dependence on spectacles and, perhaps, a need to lower their IOP may reasonably ask to have their crystalline lenses replaced earlier than was ever thought medically acceptable.

Welcome to elective cataract surgery.

Cataract extraction followed by IOL implantation, possibly the most frequently performed surgery in the world, has been traditionally associated with the “older” patient. But that association may be changing. Across the developed countries, more midlife patients are electing to undergo early cataract surgery years before they reach their 60s or 70s. “The crystalline lens ages on a continuum, slowly losing flexibility, growing in size and becoming ever more cloudy,” said Rex Hamilton, MD, associate professor of ophthalmology and director of the Laser Refractive Center at the University of California, Los Angeles.

“A 20-year-old lens is obviously much clearer and more flexible than a 50-year-old lens. So when a midlife patient has virtually no unaided near vision, and his lens no longer has the clarity of a 20-year-old, he may elect to replace his 50-year-old lens for a premium implant that will allow him more spectacle independence and sharper distance, intermediate and near vision,” Dr. Hamilton said. “This is a progressive concept that has not yet gained widespread popularity. But I believe it is a trend that will be embraced by more anterior segment surgeons as the IOL technology continues to advance and as aging baby boomers increase in numbers and seek alternatives to spectacles and LASIK surgery at an earlier age.”

New Technology Brings Demand

Indeed, recent advances in refractive lens exchange technology and techniques have given cataract/refractive surgeons something that could not even be imagined a generation ago—the ability to deliver sharp, long-term enhancement of vision to midlife patients. Dr. Hamilton described a typical scenario: “A hyperopic patient in his early 50s with vision worse than 20/40 and virtually no unaided near vision comes to my office seeking to reduce his need for glasses. With this type of patient, assuming there isn’t any macular pathology, irregular astigmatism or significant amblyopia, I will offer refractive lens exchange as opposed to LASIK. Why? Because it will best serve this patient’s visual needs in the long run. Given that this hyperopic patient will eventually need cataract surgery, refractive lens exchange [instead of LASIK] will not only help him avoid a second surgical procedure and offer more spectacle independence, but also will eliminate the challenges of IOL power selection following LASIK once cataract surgery is necessary. It comes down to minimizing surgical procedures and maximizing quality of life.”

A trend in the making. This past year, Elizabeth Yeu, MD, assistant professor of ophthalmology at Baylor College of Medicine in Houston, noticed more and more patients in their late 40s and 50s asking for refractive lens exchange. Many of these patients are requesting refractive correction while facing the onset of presbyopia. “They are coming in for refractive treatment, want to correct their near vision, yet don’t want monovision,” Dr. Yeu noted. “While many do not show symptoms of a cataract, statistics tell them that there is a good chance of developing one within the next 10 to 15 years. These patients want a permanent solution that won’t require them to return down the road for more surgery to remove a cataract.”

There are also those individuals whose corneas do not allow for corneal ablative surgery. These patients might be candidates for such alternatives as corneal inlays, “But those corneal options are still in trials in the United States and not available for the general public,” Dr. Yeu said. “These emmetropic patients do not want to wait and, instead, choose to continue with refractive lens exchange.”

Boomers keep on booming. Dr. Yeu attributes her uptick in refractive lens exchange surgeries in part to an improving economy, but also to the postwar boomers, who, according to reigning consensus, prefer active lifestyles to retirement. “We are seeing a new generation of patients who are embracing early elective cataract surgery. With dynamic careers and an increase in longevity, people are able and want to work into their later years. And they want vision that can support these goals.”

Curiously, while cataract patients are getting younger, refractive patients are getting older. H. L. “Rick” Milne, MD, in private practice in Columbia, S.C., has always had a continual stream of patients coming into his practice for refractive surgery, but the demographics appear to have shifted, with more people in their 50s and fewer in their 20s and 30s. “I am not sure if I can attribute this shift to an increase in the older population or to economic reasons, but midlife patients are wondering what they can do to become more spectacle independent,” he said.

Selecting the Right Lens

The ability to offer patients refractive lens exchange has gotten a boost from advances in presbyopia- correcting IOLs.

The ophthalmologist as tailor. Dr. Milne makes it a point to interview the patient prior to cataract surgery to tailor the choice of lens to the patient’s lifestyle.

For example, someone who has the need for intermediate vision may benefit from the AcrySof IQ ReStor, an apodized diffractive optic. “This IOL is a nice step up, but I make sure to forewarn the patient about the possibility of halos and auras at night,” Dr. Milne said.

On the other hand, a patient who does not use computers much and prefers to read books in bed at night, thus needing sharp near vision, may be a candidate for the Tecnis Multifocal IOL. “In general, I will start patients off with a Tecnis Multifocal in the first eye, and if they return doing well with good near and intermediate vision, I will use the same lens in the other eye,” Dr. Milne explained. “However, if their intermediate vision is not that good, I will use the AcrySof IQ ReStor in the second eye. This combination gives the patient excellent near and intermediate vision.”

Dr. Milne noted that lens selection should be carefully tailored to a patient’s preference and lifestyle.

His practice uses a questionnaire designed specifically to determine the extent and type of their near, intermediate and distance activities as well as to provide insight into some of their psychological tendencies.

For example, a patient who may consider himself more of a “perfectionist” may not be an appropriate candidate for refractive lens exchange. “Refractive lens exchange may take him to a good place but not a perfect place,” Dr. Milne said. “Thus, it is imperative to take the time to capture all aspects of the needs of a potential refractive lens patient.”

Pre-, Intra- and Postop

Dr. Hamilton noted that the ideal candidates for refractive lens exchange are patients who are hyperopic presbyopes and between their late 40s and early 60s. “They do well and seem to experience the quickest postoperative satisfaction,” he said. “Myopic patients also do well but take a bit longer to adapt to the multifocal optics, particularly with regard to near vision. I am still conservative in the myopic refractive lens–exchange patient for whom the risk of retinal issues with lens surgery using current IOL technology is not insignificant. It will be interesting to see in the next few years—when we have accommodative IOLs which fill the capsular bag—if the incidence of pseudophakic retinal detachment decreases in the myopic population.”

Dr. Yeu agreed about the higher incidence of retinal detachment. “This surgery causes the posterior capsule to shift forward, resulting in traction in the vitreous space, and this pulling and tugging can lead to retinal tears, holes and detachments.”

Take care with removing soft lenses. From a surgical perspective, refractive lens exchange requires more than the considerable skills already possessed by cataract surgeons who implant presbyopia-correcting IOLs, Dr. Yeu said. “Not only do you need to be a good phaco surgeon with the knowledge and ability to implant premium IOLs, but you have to be adept at working with soft crystalline lenses. Removal of softer lenses in younger patients often requires a different approach than removing dense cataract lenses from an older individual.”

Be consistent opening the capsule. Accurate lens calculations and consistent surgical technique are essential to ensure patient satisfaction with refractive lens exchange, according to Dr. Hamilton. “Warren Hill and others have taught us that the most important surgical factor we have control over to improve accuracy of IOL calculations is the capsulorhexis. If we are consistent with our capsulorhexis, we can rest assured we have taken the most vital surgical step to maximizing our refractive outcomes.” Dr. Hamilton uses a 5.5-mm inked trephine to mark the cornea. When he traces this mark, a 5.0 mm rhexis is created. This provides a 0.5 mm overlap of the 6.0 mm optic found on most multifocal IOLs.

More chair time. Throughout the entire lens-exchange process, the surgeon must be willing to take the chair time to discuss expectations with the patient. It is important to inform the individual that a certain percentage of patients will need an enhancement following the primary implant surgery. Dr. Hamilton, who performs both cataract and refractive surgeries, tells his patients: “Since you do not want to wear glasses after surgery, the bar is set much higher now than 10 years ago. Consequently, there is a 20 percent chance we will need to do another procedure like LASIK to fine-tune the outcome.” In reality, Dr. Hamilton notes, the 20 percent number is an “underpromise/overdeliver” figure: The enhancement rate is in the 5 to 10 percent range.

“This chair time is key,” Dr. Yeu stressed. “When we speak with patients, we inform them that their refractive lens exchange procedure may be a staged process and could include the need for corneal enhancement. For cataract surgeons who do not perform corneal refractive surgeries, it is important that their patients have access to those who can perform such enhancements. ”

The Glaucoma Factor

One particularly intriguing benefit of early cataract extraction is the empirical lowering of intraocular pressures in persons with mild to moderate glaucoma.

This phenomenon has been an area of research interest for Thomas W. Samuelson, MD, in private practice in Minneapolis. In 2008, Dr. Samuelson coauthored a paper showing long-term IOP reductions in hypertensive eyes following phacoemulsification and IOL implantation. The researchers discovered that the decrease was greatest in eyes with the highest presurgical IOP.¹ “We found that cataract surgery substantially lowers intraocular pressure in some patients, especially those with increased IOP,” Dr. Samuelson said. “For this reason, in our practice we consider cataract surgery an incremental step in the management of glaucoma, much like we consider each class of medication an incremental step. It does not eliminate the condition, but I am quite convinced that cataract surgery is a favorable event in the lifetime of a glaucoma patient.”

Why is IOP affected? The physiological or anatomical reasons for this modulation in IOP have not been established. Perhaps removing the cataract helps the outflow system. And since the angle width does not change in normal-tension or open-angle glaucoma patients after cataract surgery, the lowering could be due to the trabecular meshwork actually functioning better, said Dr. Samuelson.

He acknowledged that there is controversy about whether this IOP lowering effect is transient or permanent, but he tends to believe it is more long-lasting than previously thought. Consequently, a patient with elevated intraocular pressure or glaucoma seeking refractive lens exchange may benefit in several ways. The surgery may help reduce the medication burden, improve pressure control, enhance vision and improve refraction.

In the March Ophthalmology, Dr. Samuelson and his colleagues explained how they took the concept of cataract surgery for IOP reduction one step further, conducting a randomized, controlled, multicenter study comparing cataract surgery with a glaucoma drainage device (in this case the trabecular micro-bypass iStent, from Glaukos) with cataract surgery alone in patients with mild to moderate open-angle glaucoma.

Two hundred and forty eyes were randomized to either cataract surgery with (iStent) implantation or surgery alone. At one year, 66 percent of the double-treatment eyes, but only 48 percent of control eyes, achieved 20 percent IOP reduction or greater, without medication. “I believe such a minimally invasive surgical intervention will help fill a substantial need in the surgical treatment of mild to moderate glaucoma. I might add that I felt equally excited about the findings that showed that IOP is lowered after cataract surgery. To me this validates our earlier studies,” Dr. Samuelson said.

He added that cataract surgery and medicine could buy time for glaucoma patients and possibly allow them to avoid lifelong risks associated with filtering blebs including bleb-related infections. He also said that the newer, minimally invasive glaucoma procedures such as Trabectome and iStent, when coupled with cataract surgery, could provide additional options for early to moderate glaucoma. “This is why I don’t like to do trabeculectomy for mild to moderate disease,” he said. “We have other surgeries that can delay or eliminate the need and reduce risk exposure for the patient.”

Some, not all, patients will qualify. He cautioned that at this point, he would rarely remove a clear lens in a patient with no vision complaints simply to lower pressure unless the patient has experienced overt phacomorphic angle-closure glaucoma. “If they are at the point in their lives when they are beginning to experience symptoms, early cataract surgery may be a good alternative.”

Barbara A. Smit, MD, PhD, in private practice and clinical instructor at the University of Washington in Spokane, has given talks and presented case studies on glaucoma and the aging lens. She cited Dr. Samuelson’s study as well as an earlier report² noting that after cataract surgery, patients tended to run a lower pressure, and many were able to get off their medications.

“While I do not believe we should perform cataract surgery on all patients with elevated IOP, it is an adjunct consideration,” Dr. Smit said. “The possible IOP reduction with cataract surgery in the management of the glaucoma patient means they may no longer require their preoperative glaucoma medications.”

Postop pressure spike. Dr. Smit warned that a downside to cataract surgery in glaucoma patients is that 10 to 20 percent of patients undergoing cataract surgery experience a significant postoperative pressure spike. Consequently, patients must be observed very closely following surgery, particularly if they have advanced optic nerve damage. In addition, it may be prudent to stage cataract and glaucoma surgery rather than perform combined procedures. The surgeon can then determine whether the IOP is lowered adequately following the cataract surgery before continuing with the glaucoma surgery.

Dr. Samuelson agreed, saying, “The new baseline IOP will not be evident for at least six to eight weeks postoperatively—when all inflammation has subsided, the viscoelastic material has cleared and the patient is off topical steroids. Until that point, the patient must be monitored carefully and medications added back as needed.”

“There has been a lot of interest in the question of when you should take out the lens,” Dr. Smit said. “I think the standard of care is not to do early cataract surgery simply to lower intraocular pressure. I would, however, consider cataract extraction for lesser visual indications if the patient may also benefit from lower IOP.

“In particular,” said Dr. Smit, “I would consider early cataract removal in patients with chronic angle closure and uncontrolled pressure. In those cases, cataract removal can be performed along with goniosynechialysis and the angle can be reopened with subsequent IOP control. It truly depends on each patient.”

Financial Considerations

Whatever their motivation to seek out elective cataract surgery, the vast majority of patients pay for refractive lens exchange out of their own pockets. “This is the generation that is used to paying cash for such procedures as LASIK and Botox,” Dr. Yeu pointed out. “With the economy slowly coming back, and the increase in luxury item purchases, it is not surprising to me that I am seeing more and more baby boomers seeking out refractive lens exchange. This is the generation that embraces new technology, stays current with new surgical techniques via the Internet and feels comfortable with alternative treatment options.”

Moreover, insurance reimbursement may be quite possible for those patients with both early cataract and poorly controlled IOP. But no matter who pays for it, refractive lens exchange actually has yet to make a big dent in the marketplace. In fact, according to Dr. Hamilton, presbyopia-correcting lenses make up only 7 percent of the total lenses used in cataract surgery, and an even smaller percentage of these presbyopia-correcting patients are those who have chosen refractive lens exchange.

“Premium lenses have been slow to catch on, and I think a part of that is these lenses take more chair time and may require enhancements, and patient management is more intense. As a refractive surgeon, I am used to more chair time and LASIK touch-ups, so I have a higher comfort level.”

A deal for Medicare. Dr. Hamilton observed that refractive lens exchange may actually save taxpayers money in the long run as fewer patients will need cataract surgery once they reach the age they qualify for Medicare. “If you factor in that these patients will never have cataracts, this will take a huge bite out of the funds needed to pay for the most common surgery done in the United States. It’s exciting to be a part of what could be a major shift in the way we view elective cataract surgery.”

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1 Poley, B. J. et al. J Cataract Refract Surg 2008;34(5):735–742.

2 Shingleton, B. J. et al. J Glaucoma 2006;15:494–498.