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Refractive Surgery | Nov 2010

Choosing Among LASIK,Phakic IOLs,and Clear Lens Extraction

How one surgeon approaches patient selection for lens- versus laser-based refractive procedures.

For a long time, refractive surgery was synonymous with laser, and to many potential patients it still is today. As a result, some refractive surgery clinics have been reluctant to incorporate other technologies into practice, thereby offering no solutions for patients with contraindications to laser ablation. Recently, however, increasing demand from the growing presbyopic population has dramatically changed the market for refractive surgery, which now includes lens-based options.

Phakic IOLs, once used only for patients with higher refractive errors, are growing in acceptance as an alternative to surface ablation. To be able to select the best option for the patient and thereby optimize your results, incorporating intraocular surgery into your practice is now a necessity.

The variety of treatment options makes the selection process more complicated. It can be confusing to both staff and patients. This article builds a selection strategy for choosing among LASIK, phakic IOLs, and clear lens extraction.

Consider the following two questions when deciding what procedure is best for your patient.

What are the patient's preferences? Initial contact with patients is usually achieved via telephone. Whatever staff member answers the call has the first opportunity to initiate a discussion and ask about personal preferences. It is important that all staff members use the same guidelines and speak with the same voice—in other words, the patient should get the same message regardless of who the contact is. Conflicting messages will confuse the patient and erode any confidence he or she had in your clinic. We use guidelines that all employees can learn and comprehend without compromising scientific findings or clinical experience.

Most patients come to our practice through word of mouth and referrals from other patients. Sometimes these patients want the same procedure they were told about, or they might have gathered information from your (and often your competitors') Web site or other external sources. And Sometimes these patients have already decided on a specific treatment before setting foot in your clinic. If there are no clinical data contradicting the patient's choice, it is a good idea to fulfil that wish, even if it does not completely fit your guidelines.

What is the patient's age? There are two broad categories of patients, the nonpresbyopic and the presbyopic. In our clinics, the multifocal IOL is the fastest growing refractive technology. Word has spread to patients that this technology may solve the problem of presbyopia and achieve spectacle independence for reading and distance vision. If the potential patient's knowledge of multifocal IOLs is not evident in the first contact, he or she should be informed of the possibility. Many in the older generation (including cataract patients) think their age precludes them from any option that corrects their refractive error.

The evolution of multifocal IOLs has positioned these lenses as the first choice for treating presbyopia. In our clinics, we have been using most of the common multifocal IOLs for more than 10 years. Even if these lenses involve compromises and will eventually become a parenthesis in the history of refractive surgery, they deliver positive results in the vast majority of our current cases. Our patients want value for their money, and the predictability of spectacle freedom is, in our experience, worse with accommodating lenses than with multifocals. Furthermore, our patients seem to accept that they might need glasses for intermediate vision, such as computer work, rather than for reading distance, which is often the case with accommodating lenses.

The multifocal IOL we use most often is the AcrySof IQ Restor +3.0 D IOL (Alcon Laboratories, Inc., Fort Worth, Texas). The combination of the 3.00 D add and the lens' asphericity makes this IOL appropriate for most patients. After surgery, the patient is often reading sufficiently within a few days, and halos tend to fade within weeks. Depth of focus, which is often better than with other multifocal models, strengthens reading capability and increases the potential to read a computer screen at 50 or 60 cm. On the downside, reading with the Restor +3.0 D tends to be slightly worse with bigger pupils under dim conditions. Recently, Alcon released a toric version of the Restor; our initial experience with the new SND1Tx is promising. In my experience, toric lenses are appropriate in patients with more than 0.75 D of corneal cylinder. But we all know how ticklish these lenses are to any postoperative refractive error; it is a challenge to achieve emmetropia, but with secondary treatment options this is possible.

Another choice in patients with preexisting astigmatism is the AT.LISA Toric (Carl Zeiss Meditec, Jena, Germany). This lens has a slightly closer reading distance than the Restor, but it is less sensitive to pupil size. Otherwise, the AT.LISA behaves similarly to the Alcon lens.

You have to be prepared to spend more chair time with presbyopes, both before and after surgery. Before surgery, address the compromises associated with these lenses. It is easier for patients to tolerate compromises if they have accepted the circumstances prior to surgery. Unfortunately, there is no standard or reliable test to determine what personalities cope better than others with the way a multifocal IOL works.

Patients with eye diseases that compromise visual acuity and optical quality are poor candidates. Additionally, previous keratorefractive procedures can be disqualifying, especially if the procedure was done several years ago. It is therefore important to perform topography and wavefront scan to estimate optical quality; large aberrations do not combine well with multifocality.

There are other products on the presbyopic horizon, but in most cases we recommend a well-documented solution with a history of reliability. One age-old solution is monovision; however, due to a generally low acceptance rate, it is mandatory that the patient already has a working monovision prescription (I happen to be one of them) before we make it permanent.

For practical as well as medical reasons, we consider doing excimer laser surgery for patients who have refractive errors between 3.00 and -7.00 D (spherical equivalent). Table 1 shows the refractive guidelines we use at Capio Medocular. Corneal thickness often limits the use of LASIK beyond -7.00 or -8.00 D. Even if such correction is possible without compromising the cornea, regression and predictability are still wild cards. For corrections near -7.00 or -8.00 D, the surgeon must have available options for retreatment if necessary.

For greater refractive errors, we prefer phakic IOLs. Other criteria that speak in favor of phakic IOLs include preoperative pachymetry less than 500 µm, predicted postoperative pachymetry of less than 300 µm (excluding a possible flap and the option of retreatment), and any condition that could worsen after laser ablation (eg, dry eye or form fruste keratoconus). There is a constant debate regarding the importance of corneal thickness for excimer laser surgery; for the time being, with no consensus, size matters.

The latest generation of lasers, keratomes, and femtosecond lasers has made LASIK considerably safer. Flap complications and induced aberrations are now rare. Having said that, in our experience, PRK is not only a little safer than LASIK, but it has better predictability and provides better quality of vision. This is true at least for minor refractive errors. We tend to recommend PRK for up to -4.00 D (spherical equivalent), but LASIK is preferred for higher myopia or for hyperopia. Even with modern lasers, haze can occur, predictability is lower with the higher prescriptions, and a secondary procedure is less convenient with PRK. PRK with mitomycin-C is an option if neither LASIK nor phakic IOL are suitable.

We have 12 years' experience with the Visian ICL (STAAR Surgical, Monrovia, California), and we do not hesitate to implant it, even in eyes with low refractive errors. It provides impressive predictability and excellent quality of vision even with very high prescriptions. The treatment range is remarkable, covering nearly all refractive errors from 10.00 to -18.00 D, with or without astigmatism up to 5.00 D. There are few exclusion criteria for the Visian ICL, but one is age. We know that the risk of developing cataract caused by the implant increases dramatically after the age of 50 years, and the range between 45 and 50 years is a gray area. A tight protocol will limit the risk of cataract to 1% or 2%.

The fact that the procedure is reversible and that no tissue is removed seems to be appealing to patients. I share with patients the fact that I am a satisfied Visian ICL patient myself—I received the implant in 2004—and this has increased the trust in and popularity of this technology among our patients (Figure 1).

The guiding principles presented above and in Table 1 have emerged from our own practice and experience and are used to facilitate patient flow. If you asked five other ophthalmic surgeons to outline their guidelines, you would probably end up with five different versions. A guideline should never be a binding law; rules are made to be broken, and you must retain your ability to think outside the box. The option to make individual customizations and keep an open mind for new technologies is always appropriate.

For the majority of your staff, ease of use should be the main priority for your guiding principles. The important issue is to make them work with your own team and your local traditions. Implement your guidelines throughout your organization and strive to make the patient feel that every member of the staff acts professionally. Even educated and well-informed patients appreciate firm advice and want to understand that you know what you are doing. Only in this setting will patients feel safe in their choice of both clinic and procedure.

Göran Helgason, MD, is the Medical Director of Capio Medocular, Göteborg, Sweden, and Consultant at Advanced Vision Care, London. Dr. Helgason states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +4631 787 78 00; mobile: +46707 90 06 68; fax: +4631 774 28 19.