Now that there are three refractive IOLs on the market and Medicare is allowing us to charge cataract patients a premium to correct their presbyopia, many cataract surgeons are for the first time giving serious consideration to implanting multifocal and accommodating IOLs.
As someone who has been an investigator for six multifocal lenses and an active user of the Array lens (Advanced Medical Optics, Inc., Santa Ana, CA) prior to the availability of the newest IOLs [and that IOL's discontinuation], I can share some insights into the benefits and pitfalls of implanting a refractive IOL. One thing I have learned is that surgeons must be able to offer options like conductive keratoplasty (CK; Refractec, Inc., Irvine, CA) to correct hyperopic surprises.
The first thing to remember is that patients seeking refractive IOLs have high expectations. They may have heard from their friends or relatives how wonderful it is to be independent of glasses. If patients are paying out of their pockets—for a refractive lens exchange or for the extra benefits of reducing their dependence on spectacles after cataract surgery—they will surely want excellent results.
With monofocal lenses, most cataract surgeons have purposely aimed for a low myopic refractive target of approximately -0.50D in their lens power calculations. If the result is a little more hyperopic than expected, the patient will be plano and happy; if the outcome is a little more myopic than expected, the patient will get some near vision to compensate for imperfect distance vision and probably will still be happy.
Now that we are implanting IOLs like the Rezoom (Advanced Medical Optic, Inc.), Acrysof Restor (Alcon Laboratories, Inc., Fort Worth, TX), and Crystalens (Eyeonics, Inc., Aliso Viejo, CA) with a plano refractive target, minor miscalculations that make the outcome a little more plus or minus than intended are undesirable. Even a mildly hyperopic result can be difficult for patients to tolerate, because their functional vision at both distance and near is affected.
Although not a frequent problem, some hyperopic surprises are inevitable, and surgeons must be prepared to offer patients solutions other than a pair of glasses. When I was implanting the Array lens, which was offered as part of the Medicare-covered procedure, patients understood that they might need glasses postoperatively, and most were satisfied even when their vision was not right on target.
IOLs or Refractive Surgery
If a spherical error results in an unhappy patient, exchanging the lens or piggybacking an IOL is always an option. For low levels of hyperopia, however, these are more invasive, higher-risk procedures than necessary. I am most likely to offer these solutions if the refraction is off by more than 2.00D, but that degree of refractive surprise is uncommon. Usually, the unexpected hyperopic result ranges from +0.50 to +1.25D.
Other options for these patients include LASIK or PRK, but many surgeons who will implant refractive IOLs do not have access to or experience with an excimer laser. Also, some of my colleagues who perform excimer laser surgery are reluctant to absorb the high price of performing a laser enhancement.
CK, in my mind, is the most attractive alternative for low postoperative hyperopia. Between the Array cases and the newer IOLs, I have performed perhaps six rescues with CK after implanting a refractive IOL, and I have found the approach to be very successful. CK is relatively inexpensive to perform, and it is convenient for the patient and surgeon, because the procedure can be done quickly right in the office. Any surgeon who is performing phacoemulsification will find the learning curve with CK to be short. An added benefit is that, once surgeons have the device, they can also use it for Nearvision CK for presbyopic patients who do not yet need cataract surgery.
In my opinion, the safety profile of CK is excellent. For instance, it is less invasive and traumatic than bringing patients back to the OR for another intraocular procedure, and, to me, it is safer and easier than laser refractive surgery. In fact, one of the nice things about CK compared with LASIK or PRK is that you do not adversely affect the tear film, because CK severs no nerves. Additionally, there is no risk of reopening the phaco incision during CK, a concern with a pressurized microkeratome procedure, because the former requires no incision or removal of tissue.
In short, I think CK is an easy post-IOL fix for hyperopia that is safe and comfortable for the patient and less stressful for the surgeon than other options.
Typically, the patients on whom my colleagues and I have performed CK following the implantation of refractive IOLs are those with a plano result in one eye and +0.75 to +1.00D in their other eye. Because they see 20/20 in one eye and 20/40 or 20/50 in the other, these patients notice and are bothered by the difference.
Our goal is a final bilateral refraction of emmetropia or close to it so that the near portion of their refractive lens will work as it should. Because of the prolate cornea and increased depth of field that CK seems to create, it may also provide some extra multifocality that may allow for more useful intermediate vision for a patient with a lens like the Acrysof Restor.
CK in pseudophakes is an off-label procedure but one that is well within the surgeon's purview. The course of action makes a lot of sense for the correction of less than 2.00D of hyperopia or residual astigmatism. Unlike CK in post-LASIK patients, no nomogram adjustments are needed for pseudophakes.
We still do not know the precise duration of the effects of CK, but they are certainly more durable than earlier thermokeratoplasty techniques. In my hands, the results have been predictable and reproducible, and newer techniques such as Lighttouch from Rick Milne, MD, are improving on those results.
Multifocal and accommodating IOLs represent a new opportunity for cataract surgeons. It is less stressful to implant these lenses if one recognizes an opportunity for low-risk, low-trauma fine-tuning with CK, should it be necessary.
R. Bruce Wallace III, MD, FACS, is Clinical Professor of Ophthalmology at Louisiana State University Medical School in New Orleans, Assistant Clinical Professor of Ophthalmology at Tulane School of Medicine, and Director of Wallace Eye Surgery in Alexandria, Louisiana. Dr. Wallace is a paid consultant for Advanced Medical Optics, Inc., but acknowledged no financial interest in any product mentioned herein. Dr. Wallace may be reached at (318) 448-4488; firstname.lastname@example.org.