Revenues from cataract surgery are falling, and this trend is likely to continue. Today's patients are seeking premium services, and refractive IOLs to correct presbyopia seem like an obvious choice for most lens-based surgeons. Why is it, then, that the majority of patients do not receive presbyopia-correcting IOLs?
Herein, I will discuss why offering presbyopia-correcting IOLs is beneficial to you, your practice, and your patients. I have chosen to focus on multifocal IOLs because I prefer these lenses to accommodating IOLs. My preference is based on the lack of data on the physiology of accommodating IOLs versus the high volume of data on multifocal IOL optics.
REFRACTIVE ERROR OR ORGAN FAILURE?
For more than 10 years, I have advocated that presbyopia is not a refractive error. Although we treat presbyopia conventionally with spectacles, it is a physiological condition, unlike myopia, astigmatism, and hypermetropia, which are anatomically based conditions. Therefore, presbyopia should be considered organ failure that originates with the crystalline lens. There are multiple similes in medicine, including menopause, type 2 diabetes, and osteoarthritis.
Regardless of how individual ophthalmologists approach the cause of presbyopia, patients' views typically stay the same. The bottom line is that they want to achieve presbyopia correction. When cataract patients are given the choice of: (1) wearing spectacles for near vision or (2) no spectacles at all, they prefer the latter by a 2:1 ratio.1
So why do some ophthalmologists shy away from using presbyopia-correcting IOLs? My opinion is that many surgeons may be unaware of the improvements made to multifocal technology in the past 5 years.
No surgeon wants a patient who is unhappy postoperatively because of visual disturbances such as halos. It is easy to assume that extra time spent counseling patients on the side effects associated with multifocal IOLs is not worth the benefits that a premium IOL provides. In the 21st century, this scenario has lost its accuracy because surgeons no longer oversell and underperform, promising patients that they will never need glasses again. Rather, surgeons who are experienced in presbyopia correction advertise reduced-spectacle dependency. I tell my patients that one-third of the those in whom I implant multifocal IOLs will be truly spectacle independent, but that the remaining 60% of them will occasionally require near-vision correction, mainly for prolonged reading or for situations where dim illumination is present.
When we started modern presbyopia surgery in 1997—following my description of what is now called presbyopic lens exchange (PRELEX)—patient selection required an endless lists of exclusions. I advocate, however, the following simple equation for identifying potential recipients of multifocal IOLs: normal eye + normal patient + normal surgery = a good candidate.
I do not have to define a normal eye, except to say that it may have mild glaucoma, a few drusen, or background diabetic retinopathy. Similarly, I do not have to define normal surgery; if you feel stressed and unhappy during surgery, think monofocal. But how do you define a normal patient? In my practice, we avoid patients with a personality variant—specifically, anyone with unrealistic expectations.
INCORPORATING PRESBYOPIA-CORRECTING IOLs
How do you select an appropriate patient for presbyopia-correcting IOLs? If (1) the desired refraction can be obtained with an available IOL power, (2) the patient will have acceptable postoperative astigmatism, and (3) the patient has realistic expectations, the patient may be a suitable candidate for a multifocal IOL. Of course, preoperative counseling must always be performed prior to surgery. If you are interested in building presbyopia-correcting IOLs into your practice, the best strategy is to stop looking for patients who will benefit from multifocal IOLs. Change your assumption to one that makes all patients potential candidates. By doing this, you make excluded patients the minority.
Our process in my practice includes an initial screening, performed by a member of my staff, to determine if the patient is a suitable candidate for presbyopia-correcting IOLs. The patient is asked, "Do you like wearing glasses?" If the answer is yes, then they are not a candidate for a multifocal IOL; however, if they give any other answer, they are then asked, "Would you prefer an implant that will allow you to do most things without glasses rather than one that will require glasses for all near-vision tasks?" We have found that the answer is yes in twice as many cases as it is no. After a staff member provides me with his evaluation, I spend less than 3 minutes explaining to the patient that the result cannot be guaranteed and that spectacles may occasionally be necessary. I also mention that some patients experience ghost images; I prefer this term instead of halos.
In the past, ghost images occurred frequently enough that we prepared strategies for how to deal with unhappy patients. I have been criticized for offering the explanation to symptomatic patients in the early postoperative that this phenomenon signifies that the lens is working properly. Part of being a good doctor is treating the whole patient and not just an eye in isolation. Reasurring a patient is good medicine. It does not mean that you are ignoring or refusing to recognize his symptoms.
Ghost imaging is not as big an issue as it was even 1 year ago. I have worked with a variety of IOL manufacturers to improve IOL design. Recently, I have been involved in the production of a series of multifocal IOLs called M-Flex (Rayner Intraocular Lenses, Ltd., East Sussex, UK). These are available with a 3.00 D or 4.00 D add. The latter is available as distant dominant (65%) or near dominant (65%). Made of a hydrophilic acrylic with a relatively low refractive index, M-Flex IOLs have an extremely low incidence of ghost images (ie, approximately 3%; personal communication with Julian Cezon, MD). This is a major step forward in presbyopia-correcting surgery.
Surgically induced astigmatism is another reason that some surgeons do not use multifocal IOLs. If the patient had 1.50 D of astigmatism preoperatively, we aim for the residual astigmatism to be no more than 1.00 D. In these cases, limbal relaxing incisions or arcuate keratotomy incisions, both of which have some degree of unpredictability, are beneficial. Both Rayner and the Acri.Tec IOLs from Carl Zeiss Meditec AG (Jena, Germany) offer a multifocal, toric, aspheric IOL, both of which have effectively made astigmatism a former contraindication. Postsurgical treatment has also improved for the surgeon with newer IOL technology. Patients are easier to manage because ghost images and astigmatism are no longer problematic.
Presbyopia correction is what many patients who undergo cataract surgery desire. In my experience, using multifocal IOLs to correct presbyopia is predictable, easy, and rewarding. I urge surgeons to build presbyopia-correcting IOLs into their practices, and I think many who do will be surprised just how much the benefits outweigh the drawbacks.
Charles Claoué, MA(Cantab), MD, DO, FRCS, FCROphth, FEBO, MAE, is a Consultant Ophthalmic Surgeon at The Queen's Hospital, BHR Hospitals NHS Trust, London, an Honorary Clinical Lecturer at the University of London, and Honorary Consultant Ophthalmologist at the Academic University of Pretoria. Dr. Claoué states that he is a consultant to and has a royalty agreement with Rayner Intraocular Lenses, Ltd. He may be reached at tel: +44 20 88 52 85 22; fax: +44 20 82 65 32 89; eyes@dbcg.co.uk.
