Apodized aspheric multifocal IOL boosts spectacle independence and patient satisfaction

A graduated diffractive zone minimized glare and halos, and an extended near focal point improved intermediate vision, a study showed.

Bilateral implantation of an aspheric multifocal IOL optimized near visual acuity, offered good intermediate vision and produced few visual disruptions, according to a study.

The lens also yielded high rates of patient satisfaction and spectacle independence, the data showed.

Patients received the AcrySof IQ ReSTOR SN6AD1 apodized diffractive aspheric multifocal IOL (Alcon) with a +3 D addition.

Thomas Kohnen, MD, lead study author, said a pseudoaccommodative effect dramatically reduced spectacle dependence compared with more common monofocal lenses.

Thomas Kohnen

“When we have a monofocal lens, which is still the worldwide standard, you still have to wear reading glasses in about 85% [of cases]. Sometimes you have some pseudoaccommodative effect, but usually somebody who gets a monofocal lens needs reading glasses,” Prof. Kohnen told Ocular Surgery News in a telephone interview. “Here, you don’t need reading glasses because you have near visual acuity focals. That’s a great benefit.”

The AcrySof IQ ReSTOR SN6AD1 IOL has a 6-mm optic, central 3.6-mm apodized diffractive zone and outer refractive zone. The diffractive steps gradually descend from the center to the periphery to reduce glare and halos and facilitate the transition to distance vision. The lens design incorporates negative spherical aberration that offsets positive corneal aberration, according to the study abstract.

An earlier version of the aspheric lens, the AcrySof IQ ReSTOR SN6AD3 IOL, had a +4 D addition with a shorter near focal point that some patients considered problematic, Prof. Kohnen said.

The U.S. Food and Drug Administration approved the ReSTOR SN6AD1 in 2008.

Results of this study were published in the Journal of Cataract and Refractive Surgery.

Patients and procedures

The prospective, multicenter study included 186 eyes of 93 patients who underwent cataract extraction or refractive lens exchange. The group comprised 147 hyperopic eyes (79%), 37 myopic eyes (20%) and two emmetropic eyes (1%). Maximum hyperopia was 4.5 D spherical equivalent and maximum myopia was 7.1 D spherical equivalent. Mean patient age was 62 years.

IOLs were inserted through 2.2-mm to 3.2-mm incisions with Monarch II or III injectors (Alcon). Mean incision size was 2.4 mm. The interval between first- and second-eye surgeries was 7 to 30 days.

Investigators assessed logMAR visual acuity with distance correction using the ETDRS chart at 4 m for distance vision. A new ETDRS chart was used to assess near vision at 40 cm and intermediate vision at 60 cm.

Patients completed questionnaires at intake and postoperative visits.

Investigators conducted postoperative evaluations at 1, 3 and 6 months after second-eye surgery. Posterior capsule opacification, IOL centration and tilt were assessed. Three eyes of two patients underwent LASIK enhancement between the 3-month and 6-month assessments.

Optimal distance and visual disruption

Study data showed mean binocular distance-corrected visual acuity at near, intermediate and far distances was statistically significantly improved in the 81 patients who underwent preoperative and 6-month postoperative assessments (P < .001), the authors reported.

At 6 months, mean uncorrected logMAR visual acuity was –0.03 at 4 m, 0.20 at 70 cm, 0.13 at 60 cm, 0.05 at 50 cm and 0.04 at 40 cm. More than 98% of patients had Snellen equivalent near and distance visual acuity of 20/40 or better. Snellen equivalent visual acuity was 20/40 or better at all three distances for 76% of patients.

Mean patient satisfaction was 8.3 out of 10 and 88% of patients achieved spectacle independence.

Optimal near reading distance was 37 cm with the newer +3 D lens, compared with 32 cm for the earlier +4 D lens, Prof. Kohnen said.

“The patients get the best near correction a little bit further away, which is more convenient for most patients, because 32 cm is pretty close to the eye,” he said.

The near and far focal points are closer, reducing a decline in intermediate vision between the points, Prof. Kohnen said.

“That means that now we have intermediate visual acuity deteriorating from 40 cm instead of from 30 cm, and that gives us better intermediate visual acuity compared to the +4 D [lens],” he said.

Visual disturbances were comparable to those experienced with the previous IOL and diminished over time.

“Some people don’t like that, but they can suppress one picture. … Almost 98% of [patients] can live with it,” Prof. Kohnen said. “They know it’s there, and it usually goes away or diminishes over time. From 1 month to 3 months to 6 months or 12 months, you see a decrease.” – by Matt Hasson

Reference:

• Kohnen T, Nuijts R, Levy P, Haefliger E, Alfonso JF. Visual function after bilateral implantation of apodized diffractive aspheric multifocal intraocular lenses with a +3.0 D addition. J Cataract Refract Surg. 2009;35(12):2062-2069.

• Thomas Kohnen, MD, can be reached at Department of Ophthalmology, Goethe-University, Theodor-Stern-Kai, 60590 Frankfurt/Main, Germany; +49-69-6301-6739; fax: +49-69-6301-3893; e-mail: kohnen@em.uni-frankfurt.de. Prof. Kohnen is a consultant for scientific advice to Alcon.