Various ophthalmologists are currently implanting two different presbyopia-correcting IOLs in a given patient's eyes. Their goal is to balance out the drawbacks of one IOL technology with the advantages of another. The main reason to implant the same presbyopia-correcting IOL technology bilaterally is that the practice is supported by short- and long-term data from prospective, randomized FDA clinical studies of the Acrysof Restor IOL (Alcon Laboratories, Inc., Fort Worth, TX), Rezoom lens (Advanced Medical Optics, Inc., Santa Ana, CA), and Crystalens accommodating IOL (Eyeonics, Inc., Aliso Viejo, CA), research involving hundreds of patients.
Three presbyopia-correcting IOLs are currently available in the US, and this section addresses each in turn.
Approved by the FDA in 2003, the Crystalens IOL's FDA and postmarket data (Figures 1 to 3) provide excellent insight into the expected outcomes, risks, side effects, and limitations of this lens. The FDA approved the Acrysof Restor and Rezoom multifocal IOLs in 2005. The FDA data for both lenses demonstrate excellent outcomes. Success is not only defined by typical refractive outcomes (20/20 rates for distance, near, etc) but perhaps more importantly by spectacle independence (Figures 4 and 5), which reflects how they function in the real world.
Most patients in the FDA studies of the Rezoom lens and Acrysof Restor IOL achieved freedom from spectacles. Moreover, Richard Mackool, MD; Robert Lehman, MD; and Robert Kaufman, MD, have demonstrated 95%, 90%, and 100%, respectively, spectacle freedom in their independent postmarket studies of the bilateral implantation of Acrysof Restor IOLs.1 Similarly, Efekan Coskunseven, MD, and Farrell Tyson, MD, shared with me in 2005 that they had demonstrated 100% and 92%, respectively, spectacle freedom in their postmarket studies of bilaterally implanted Rezoom IOLs. These data clearly demonstrate success with the bilateral implantation of both lens designs.
MIXING AND MATCHING
Every IOL technology has a limitation. Although distance and intermediate vision are generally excellent with bilaterally implanted Crystalenses, the reproducibility of the outcomes is variable, and patients often use glasses for near tasks. With bilateral implantation of the Acrysof Restor IOL, patients typically have superb distance and near vision, but some are dissatisfied with their intermediate vision. A number of patients have also experienced decreased near vision in dim lighting. Those who receive the Rezoom IOL in both eyes typically have excellent distance and intermediate vision, but some patients are dissatisfied with their near vision, particularly in bright lighting conditions.
The idea behind mixing and matching technologies is to implant a lens (eg, a Rezoom IOL or a Crystalens) in the patient's second eye to complement the presbyopia-correcting lens (eg, the Acrysof Restor IOL) that they received in their first eye. Theoretically, this approach makes sense. In clinical practice, however, the vast of majority of patients do not require combined IOL technologies, as demonstrated by the FDA and postmarket studies of these three lenses.1 Furthermore, and more importantly, there are not enough short- or long-term data to identify the risks, benefits, limitations, and side effects of combining different IOLs.
Combining presbyopia-correcting IOLs may also give rise to a host of new problems. Each technology presents different visual distortions, night vision symptoms, and visual limitations. What are the compromises of mixing technologies? Will stereopsis be affected? Which patients will benefit from mixing lenses, and which will not? Will mixing technologies correct the problems that patients might have experienced with the bilateral implantation of the same IOL?
Mixing and matching technologies essentially presents a modified form of monovision, which targets one eye for intermediate and the other for near vision. This option may work well for some patients. Not everyone tolerates monovision, however, and surgeons do not yet completely understand which patients will be successful with blended vision. Although a few studies of combined IOL technologies are becoming available,2 the number of eyes thus far is quite small, and the follow-up is relatively short.
My patients have enjoyed a high rate of success (rates of spectacle freedom and satisfaction are both greater than 90%) with the bilateral implantation of either the Acrysof Restor IOL or the Rezoom lens. In my practice, the need to mix multifocal IOLs is therefore uncommon. The majority of my clinical experience is with the former lens. I have no clinical experience with the Crystalens, so my subsequent comments are limited to the two multifocals.
I explain to patients preoperatively that the Acrysof Restor and Rezoom IOLs are designed for bilateral implantation. The occasional patient who has some issues (eg, intermediate or night vision symptoms) after surgery on his first eye almost always experiences resolution or great improvement of these symptoms after receiving the same implant in his fellow eye. For example, with the Acrysof Restor IOL, either patients' intermediate vision is adequate to allow them freedom from spectacles, or they adapt by moving slightly closer to their computer screens or sheet music. My presbyopia-correcting practice is growing.
I have mixed the Acrysof Restor and Rezoom IOLs as part of an ongoing, prospective, randomized clinical study. I have preliminary results for the first seven patients, all of whom are satisfied with their distance vision. Five are happy with their blended intermediate and near vision. Their depth of field seems to be greater compared with patients in my past experience who received the same IOL in both eyes. Two of the seven patients, however, are unhappy with their results. They describe blurring of their intermediate and near vision. Perhaps they will experience improvement in time, as is often the case with monovision. In fact, it may be reasonable to look for a history of successful monovision or to attempt a monovision trial before considering mixing IOL technologies.
All of the patients say that nighttime halos are more noticeable in their Rezoom eyes, but none feels limited by daytime or nighttime visual symptoms. Based on my limited experience, there will be drawbacks to mixing IOL technologies. Whether they outweigh the potential benefits of this approach remains to be seen.
There may be clinical indications for mixing and matching lens technologies. Until surgeons better understand the limitations, risks, and side effects of this approach (only to be achieved through prospective clinical studies with adequate follow-up), my advice is to implant the same presbyopia-correcting IOL bilaterally. This practice has the support of short- and long-term data, and it is the standard of care.
Kerry D. Solomon, MD, is Professor of Ophthalmology, Medical Director of the Magill Laser Center, and Director of the Magill Research Center, all at the Storm Eye Institute, Medical University of South Carolina, Charleston. He is a consultant to Advanced Medical Optics, Inc., and Alcon Laboratories, Inc. Dr. Solomon may be reached at 843-792-8854; firstname.lastname@example.org.
1. Lehmann RP. Combining liquefaction with Restor technologies for safe and effective outcomes. Paper presented at: The Hawaiian Eye 2006 Meeting; January 16, 2006; Maui, HI.
2. Bucci F. Combining IOLs: early results. Paper presented at: The 2005 Refractive IOL Symposium; December 3, 2005; Las Vegas, NV.