New aspheric IOL designed to avoid inducing aberrations

January 1, 2006

Lisbon, Portugal—A comparison study of the new aspheric SofPort Advanced Optics (AO) IOL (Bausch and Lomb) and a "parent" model, the conventional Soflex IOL, supported the manufacturer's claim that the AO lens does not induce aberrations, said Roberto Bellucci, MD, chief of the Ophthalmic Unit, Hospital of Verona, Italy.

"This lens is designed not to change the aberrations already present at the corneal surface," said Dr. Bellucci, who spoke during the European Society of Cataract and Refractive Surgeons annual meeting. According to the manufacturer, the SofPort AO lens is "aberration free" and thus reduces spherical aberration for better vision quality relative to standard spherical IOLs, he said.

Pseudophakic spherical aberration is composed of both corneal spherical aberration, which is usually positive, and the IOL spherical aberration, which formerly was usually positive and now is adjustable, Dr. Bellucci explained.

"What we could demonstrate in this study is that this lens is an improvement over the parent spherical IOL and is not dependent on centration because internal coma was lower in eyes with the Advanced Optics IOL than in eyes with the parent spherical IOL," Dr. Bellucci said.

Because the new AO IOL has constant power at every point, from the center toward the periphery, it theoretically would avoid induced aberrations and be less dependent on centration, he added.

Internal aberrations

"We can compare those aberrations, and by subtracting the Zernike polynomial referring to the cornea from the polynomial referring to the entire eye, we can obtain the internal aberrations. The internal aberrations in a pseudophakic eye are related more than 90% to the IOL," Dr. Bellucci said.

He selected 20 eyes to have the new SofPort AO IOL with a constant power implanted so that the IOL corrected its own spherical aberrations rather than correcting spherical aberration of the cornea. These eyes were compared with 20 eyes with the spherical Soflex SE implanted.

Ten aphakic eyes were also included in the study because they are ideal for assessing the extent of change in aberrations caused by an IOL. "In aphakic eyes we can expect that the corneal surface aberrations are the same as the aberrations of the entire eye," Dr. Bellucci said.