INTRAOCULAR LENSES

Give Them What They Want

If you're preparing to offer premium IOLs to your patients, choose a lens that can help you succeed.

By Bret L. Fisher, MD

Among the many decisions you'll be making as you transition from training to practice is whether to include presbyopia-correcting IOLs among the services you'll offer to patients. Because the number of patients interested in these premium lenses has continued to increase, they'll likely become part of your repertoire. The practice you join already may have this segment up and running, or it may be counting on you, the new associate, to spearhead the effort. Either way, you'll need to familiarize yourself with the lens options and determine which ones provide the best chance for success.

Success with presbyopia-correcting IOLs is all about patient satisfaction, which is why the lens in this category that I implant most often is the AcrySof IQ ReSTOR IOL +3.0 D (Alcon). This lens utilizes a mature technology that allows me to provide very good, consistent results for a wide range of patients. I participated in the clinical trial that led to its approval by the FDA,¹ so to help you prepare for working with these technologies I have provided a summary of the 6-month trial results in this article. In addition, I have highlighted key design aspects of the lens and what I've learned while using it in my practice.

Unique Optics Produce Quality Vision at All Distances

The AcrySof IQ ReSTOR IOL +3.0 D (model SN6AD1) is built on the same platform as the AcrySof IQ ReSTOR IOL +4.0 D (model SN6AD3), which was approved by the FDA in 2007. Both models have a 3.6-mm apodized diffractive optic centrally. Apodization improves the distribution of light energy to the retina because the diffractive step heights from the center of the lens toward the periphery are gradually reduced and blended. This improves the crispness of vision and reduces light scatter, aberrations and visual disturbances compared with other lens designs, especially in low light.

Both models are also refractive in the periphery. The refractive region of the optic is dedicated to distance vision, directing light to a distance focal point for larger pupil diameter, which produces fewer visual disturbances than lenses that have a full diffractive optic.

The AcrySof IQ ReSTOR IOL +3.0 D was designed so that doctors and patients would have an additional choice of add power for the lens. The +3.0 D add power (~ +2.5 D at the spectacle plane) was achieved by reducing the number of diffractive steps from 12 to 9 and slightly widening the step spacing. As a result, intermediate vision improves and the focal point for the clearest near vision is 2.4-2.8 inches (~ 6-7 cm) farther out than with the AcrySof IQ ReSTOR IOL +4.0 D. From approximately 13-28 inches, patients have high-quality vision. In that entire range, they can see and function well for most common activities such as reading. Most patients can also work on the computer without eyeglasses. In other words, the +3.0 D model of the lens provides a larger “sweet spot” for clear vision.

Like the +4.0 D add model, the +3.0 D lens is aspheric. It compensates for positive corneal spherical aberration, which enhances image quality compared with spherical lenses. The combination of the asphericity, +3.0 D add power and apodization means there's very little trade-off for achieving a much wider range of useful vision. While patients can experience glare and halo with any IOL, the AcrySof IQ ReSTOR IOL +3.0 D minimizes visual disturbances as compared to other multifocal IOLs.

Clinical Trial Confirms Benefits of +3.0 D Add Power

The purpose of the study that led to FDA approval of the AcrySof IQ ReSTOR IOL +3.0 D was to confirm that the increase in the distance of near vision it provides didn't negatively impact near or distance visual acuity or visual disturbances compared with the IQ ReSTOR IOL +4.0 D. The pro-spective, randomized, patient-masked clinical trial, which involved 279 patients at 12 centers, confirmed this.

In the trial, cataract surgery patients were randomly assigned to bilateral implantation of either the +3.0 D or the +4.0 D IOL. According to the results, assessed binocularly, the mean best distance for uncorrected near visual acuity was 31 cm in the +4.0 D group and 37 cm in the +3.0 D group (Figure 1). In addition, the two IOLs provided equivalent near and distance visual acuity.

Figure 1. Many patients appreciate that they can hold reading material 6-7 cm farther away with the AcrySof IQ ReSTOR IOL +3.0 D than they would with the AcrySof IQ ReSTOR IOL +4.0 D.

Furthermore, mean uncorrected intermediate visual acuity at 50 cm and 60 cm was approximately one Snellen line better in the +3.0 D group than in the +4.0 D group, a clinically significant difference (Figure 2). Mean distance-corrected intermediate visual acuity in the +3.0 D group was clinically and statistically significantly better than in the +4.0 D group at 50 cm, 60 cm and 70 cm (Figure 3).

Figures 2 and 3. Patients in the clinical trial who received bilateral AcrySof IQ ReSTOR IOLs with a +3.0 D add power experienced better intermediate vision than those who received the same lenses with a +4.0 D add power.

The binocular defocus curves derived from the trial (Figure 4) also illustrate the differences in outcomes achieved with the two lenses. Although the near peaks differed by 6-7 cm as described above, patients in both groups achieved similar levels of visual acuity at the near and distance peaks. However, the curve for the +3.0 D group showed a mean binocular intermediate visual acuity of 20/32 or better, which was one to two Snellen lines better than the +4.0 D group. Also, patients in the +3.0 D group had intermediate visual acuity of 20/25 or better from 40-70 cm as opposed to 25-40 cm in the +4.0 D group.

Figure 4. Binocular defocus curves from the clinical trial comparing the AcrySof IQ ReSTOR +3.0 D and +4.0 D IOLs illustrate that patients achieved a wider range of 20/25 or better intermediate vision with the +3.0 D lens.

Patients in the trial completed questionnaires to subjectively assess their post-operative vision. At 6 months, there were no statistically significant differences in any mean visual disturbance score between the two groups. When the 3-month and 6-month data from the trial were compared, mean difficulty ratings for many potential visual disturbances, including halos and glare, had decreased in both groups (Figures 5 and 6). A high percentage of patients, who received the +3.0 D lens (78%), reported never having to wear spectacles. That percentage likely would have been even higher if investigators had been permitted to correct astigmatism.

Figures 5 and 6. In the clinical trial comparing the AcrySof IQ ReSTOR +3.0 D and +4.0 D IOLs, patients rated visual difficulties as less severe at 6 months compared with at 3 months.

My Personal Experience

In my own clinical practice, I routinely assess patient satisfaction. Approximately 90% of my AcrySof IQ ReSTOR IOL +3.0 D patients report not having to wear spectacles at all, and they all consistently rate their experience a 9 out of 10. Their range of quality vision post-operatively is excellent, and they have few complaints. I've been especially impressed with how few patients tell me they have difficulty reading in low light. I also find my +3.0 D patients are more eager to proceed with second-eye surgery and seem to adapt more quickly and easily to their new vision after bilateral implantation than my +4.0 D patients. As an added bonus, all of these factors mean they need less chair time with me.

I consider the AcrySof IQ ReSTOR IOL +3.0 D an excellent addition to the currently available options in presbyopia-correcting lenses. Take a look at “Keys to Success” on page 7 for some pointers you may find helpful as you enter this exciting new era of cataract surgery. nMD

REFERENCE

1. Maxwell WA, Cionni RJ, Lehmann RP, Modi SS. Functional outcomes after bilateral implantation of apodized diffractive aspheric acrylic intraocular lenses with a +3.0 or +4.0 diopter addition power: randomized multicenter clinical study. J Cataract Refract Surg 2009;35:2054-2061.