Multifocal offers excellent distance vision

Sydney, Australia-A study of a multifocal IOL (ReZoom, Advanced Medical Optics [AMO]) found that it provides excellent distance vision and that there is less degradation of image quality than with diffractive IOLs, according to Alman E. Ogane, FRANZCO, in private practice here.

With the lens, most patients could perform the general activities of daily living without the need for glasses. Intermediate vision, however, was not as good as expected and did not improve over time after surgery, he said. Also, patients experienced glare and halos, and near vision was not as good as with diffractive IOLs.

"The principle of the refractive multizonal IOL is that there is a curved anterior edge that refracts light to different foci, theoretically providing light for distance, intermediate, and near vision," Dr. Ogane said. The original multizonal refractive IOL (Array, AMO) has been in existence for a decade now, he said, noting that that lens has five concentric zones; zones 1, 3, and 5 are weighted for distance vision, zones 2 and 4 are for near vision, and the intermediate areas between zones are for intermediate vision.

The IOL in the recent study represents a "modified, improved version" of the older technology, Dr. Ogane said. Zone 3 has been enlarged and moved out, increasing the size of the distance and the near-dependent zones, he said, and zones 4 and 5, thought to be responsible for most of the halos and glare, are now thinner.

The new IOL provides +3.5 D near add at the IOL plane, equivalent to slightly more than +2.0 D of near add, Dr. Ogane said. The IOL has a three-piece design made of hydrophilic acrylic material with polymethylmethacrylate haptics and a 6.0-mm optic. It is available in a range of powers from 6.0 to 30.0 D, in 0.5-D increments, he said.

According to Dr. Ogane, a great advantage of the lens is the design of the edge of the optic, because it minimizes glare and internal reflections as well as the development of posterior capsular opacification (PCO). "The PCO rates with the [older lens] are about 1% at 12 months, and this can likely be safely extrapolated to the [newer] IOL," he said.

Dr. Ogane also said that the newer lens has the benefit of excellent centration, even in patients with a weakened capsular bag. Implantation of the lens into the sulcus also is possible.

He and the study's co-author, Con N. Moshegov, FRANZCO, FRACS, evaluated the newer IOL in 36 eyes of patients following phacoemulsification of cataractous or clear lenses. All patients in this prospective study had presbyopia and hyperopia and had less than 1 D of astigmatism and no other ocular pathology. Patients were followed for a minimum of 3 months.

The implantation technique required the creation of a clear corneal incision, topical anesthesia, and a capsulorhexis that was smaller than the optic.

Cataracts were removed via phaco or a liquefaction device (AquaLase, Alcon Laboratories).

The visual outcomes were very good, Dr. Ogane reported. One month after implantation, 20/30 or better uncorrected distance visual acuity was achieved in 77% of patients, and this level of vision was stable at the 3-month follow-up.

"The near results at 1 month indicated that 66% of patients were able to see J4 or better, and this improved at the 3-month time point to 82%," he said.

The intermediate vision, measured at about 60 cm, did not reach the investigators' expectations, however. About 60% of patients were able to read J8 or better 1 month after IOL implantation. This percentage remained stable at 3 months.