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Up Front | Oct 2008

Diffractive Plus Refractive

There is no such thing as one single multifocal IOL that can fulfill the needs of all patients.

Until a means to restore the accommodation of the human crystalline lens is discovered, we must use the best presbyopia-correcting IOL that the market offers. Among the options currently available, there are diffractive designs, such as the Tecnis Multifocal (Advanced Medical Optics, Inc., Santa Ana, California) and the AcrySof Restor (Alcon Laboratories, Inc., Fort Worth, Texas), and zonal refractive designs, such as the ReZoom (Advanced Medical Optics, Inc.).

I have implanted more than 1,200 multifocal IOLs. We started to implant the Restor when it first became available. The results for near vision with the Restor were good, although complaints about vision in mesopic conditions and intermediate vision were fairly high (17%). That caused us to look for other multifocal IOL technologies, and we began to implant the Tecnis Multifocal. The Tecnis Multifocal is a three-piece foldable silicone IOL with a 6-mm optic that has a diffractive posterior surface and a modified prolate anterior surface that compensates for the cornea's positive spherical aberration. The Tecnis Multifocal IOL creates two focal points 4.00 D apart, meaning in clinical practice that it provides excellent near and far vision but less strong intermediate vision.

There is no such thing as one single multifocal IOL that can fulfill the needs of all patients. Another reality is that our patients ask for excellent full-range vision: near, distant, and intermediate. The ReZoom multifocal IOL is a three-piece acrylic IOL with an OptiEdge design; the refractive surface has five optical zones with transition zones for improved intermediate vision. I use this IOL to compensate for the deficiency in intermediate vision that the Tecnis and Restor provide. Currently in my practice when using multifocal IOLs, which I do in 60% of my cataract surgeries, I use a mix-and-match approach.

The best patients for a multifocal IOL are those who do not like to wear spectacles, who have hyperopia or moderate myopia, and who agree that they can tolerate the secondary side effects that every multifocal IOL may have. I have a 4.7% incidence of severe halos with a mix-and-match approach. But when this group of patients was asked if they would like to exchange these lenses for monofocal IOLs, no one said yes. Neural adaptation is achieved by 3 months after implantation of multifocal IOLs in most patients.

WHICH ONE FIRST?
The Tecnis Multifocal IOL is always implanted first, regardless of which eye is dominant. The reason I do this is to fulfill the immediate need of patients for near vision. We then pursue intermediate vision when we implant the ReZoom in the second eye. In the past, as most surgeons recommend, I had implanted the distance-dominant ReZoom IOL first in the dominant eye, but sometimes patients were not satisfied with their near vision, and this first impression regarding the success of the surgery was difficult to change.

In a prospective cohort of 84 patients with bilateral cataracts, we compared two combinations of multifocal IOLs.1,2 Each patient underwent standard phacoemulsification cataract surgery in both eyes; 42 consecutive patients (84 eyes) received bilateral ReZoom multifocal IOLs, and 42 patients (84 eyes) received a Tecnis Multifocal in the first eye and a ReZoom in the second. Preoperative and 3-month postoperative distance and near UCVA and BCVA were compared, as well as spectacle independence for near, intermediate, and distance vision; unwanted visual symptoms; and patient satisfaction.

There were no statistically significant differences between pre- and postoperative distance UCVA between the two groups. Mean logMAR acuities were 0.09 and 0.08 for the ReZoom/ReZoom group (group A) and Tecnis/ReZoom group (group B), respectively (P=.68). Twenty-eight patients in group A (66.7%), and 29 in group B (69.1%) achieved 20/25 or better distance UCVA postoperatively. All patients in both groups achieved J3 or better near UCVA postoperatively. However, 30 patients (71.4%) in group A achieved J1 to J2 UCVA, compared with 38 (90.4%) in group B.

Regarding patient satisfaction, 40 patients in group A (95.2%) and 41 (95.2%) in group B stated that they would choose to have the same lens implanted again after the second eye implant. Asked whether they could perform intermediate vision activities, such as watching television, using a computer, or using a cell phone without spectacles, 88.7% in group A and 89.2% in group B said yes. There were no statistically significant differences in these values between groups. It is important to note that despite improvements in calculating IOL power, residual spherical and cylindrical refractive error persists; in our experience, approximately 10% of patients with multifocal IOLs implanted need LASIK enhancement.

We concluded that patients implanted with the combination of a Tecnis and a ReZoom multifocal IOL showed postoperative distance UCVA and BCVA similar to those with bilateral ReZoom IOLs while achieving significantly better near UCVA. This likely leads to increased postoperative spectacle independence. These results support my preference to use a mix-and-match approach to multifocal IOLs in my clinical practice.

Luis Izquierdo Jr., MD, MMs, practices at the Instituto de Ojos in Lima, Peru. Dr. Izquierdo states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +511 2241363; fax: +511 2254444.

Maria A. Henriquez MD, practices at the Instituto de Ojos in Lima, Peru. Dr. Henriquez states that she has no financial interest in the products or companies mentioned. She may be reached at tel: +511 2241363; fax: +511 2254444; e-mail: mariale_1610@hotmail.com.

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