Lens strategies enhance depth of focus

June 15, 2012
Lynda Charters

Different approaches for correcting presbyopia are associated with various advantages and disadvantages.

Key Points

Dr. Pepose and co-author Mujtaba A. Qazi, MD, conducted a prospective, randomized, partially masked, two-site study to compare the performance of three FDA-approved IOLs designed to improve distance, intermediate, and near visual acuity levels in adults aged more than 40 years who underwent cataract extraction. IOLs evaluated were the Crystalens AO IOL (AT-50AO) (Bausch + Lomb), the AcrySof ReSTOR 3.0 IOL (SN6AD1) (Alcon Laboratories), and the Tecnis Multifocal IOL (ZMA00) (Advanced Medical Optics). All patients had the same IOL implanted in both eyes.

The study's primary outcome measure was the logarithm of the mean mesopic contrast sensitivity (without glare at five spatial frequencies). Secondary outcomes were high- and low-contrast visual acuity, uncorrected distance visual acuity (UCDVA), uncorrected intermediate visual acuity (UCIVA), and uncorrected near visual acuity (UCNVA) at 16 and 32 inches; optical scatter; depth of focus; visual quality metrics; glare; and patient satisfaction, Dr. Pepose explained. He is in private practice at the Pepose Vision Institute, and professor of clinical ophthalmology, Washington University School of Medicine, St. Louis.

The high-contrast manifest refraction spherical equivalent 1 month after implantation was more minus for the Crystalens AO IOL, because the non-dominant eye was targeted up to –0.5 D; the add for the Crystalens AO IOL was about 1.5 D, with minimal add for the ReSTOR and Tecnis Multifocal IOLs, Dr. Pepose noted.

Evaluation of the high-contrast monocular and binocular UCDVAs 1 month postoperatively indicated that the Tecnis MF was significantly better (p = 0.015) than Crystalens AO IOL. Dr. Pepose theorized this was likely due to the myopic postoperative refractive error in the patients with the Crystalens implanted. There were no significant differences in the other comparisons between the Crystalens and the ReSTOR IOLs (p = 0.30) or the ReSTOR and the Tecnis Multifocal IOLs (p = 0.31).

Evaluation of the high-contrast monocular and binocular UCIVAs at the same time point postoperatively found that Crystalens AO IOL was significantly (p < 0.01) better than the other two IOLs. The monocular and binocular distance-corrected intermediate visual acuities (DCIVAs) were also superior with Crystalens AO IOL to the Tecnis Multifocal IOL, negating any impact of residual refractive error. The better binocular DCIVA with the Crystalens AO IOL approached significance (p = 0.06) compared with the DCIVA achieved with the ReSTOR IOL.

Evaluation of the high-contrast monocular and binocular UCNVA at 1 month showed that the ReSTOR IOL was superior at 16 inches. The monocular ReSTOR provided better UCNVA at 16 inches than the Tecnis Multifocal IOL, but no significant difference was found for binocular visual acuity.

The monocular and binocular multifocal IOLs provided significantly (p < 0.001) better high-contrast distance-corrected near visual acuity (DCNVA) than the Crystalens AO IOL, but there was no significant difference between the binocular ReSTOR and Tecnis Multifocal IOLs.

The monocular Crystalens AO IOL had a lower halo score compared with the monocular Tecnis Multifocal IOL, and the binocular Crystalens AO IOL trended toward a lower score compared with the Tecnis Multifocal IOL.

Studies using the Visiometrics HD Analyzer showed that monocular Crystalens AO IOL width at 10% of the point spread function (PSF) height approached significance (p = 0.055), with the PSF width being narrower for the Crystalens AO IOL compared with the ReSTOR IOL.

At 3 months postoperatively, the trend for the Crystalens AO IOL objective scatter index was less compared with either of the multifocal IOLs (p = 0.10).