Aspheric toric bifocal IOL plus co-axial microincisional surgery is 'successful'

January 1, 2009

An aspheric implant (Acri.LISA Toric 466 TD IOL, Carl Zeiss Meditec) corrects astigmatism and presbyopia and can be implanted through a >1.5-mm incision to avoid surgically induced astigmatism and minimize induced aberrations. The optic is designed for optimal visual quality and the haptics for rotational stability. Excellent outcomes, including high patient satisfaction, have been achieved implanting this IOL after co-axial microincisional surgery using a phacoemulsification platform (Oertli).

Key Points

"Many patients with astigmatism are interested in . . . implantation of a presbyopia-correcting IOL," said Dr. Breyer, Augenheilkunde an den Schadow Arkaden, Düsseldorf, Germany. "However, correcting the astigmatism with incisional techniques does not always provide reliable results, and the outcomes can change over time.

"The combination of CO-MICS with this bifocal toric IOL is a perfect marriage for providing these patients with successful outcomes," he said.

The biconvex plate style implant has a four-haptic design to provide rotational stability and centration that are critical to good long-term outcomes. It features an aspheric design on the front and back surfaces, which has benefits for improving contrast sensitivity, increasing depth of focus, and reducing vision symptoms at night. The toricity component is on the anterior surface of the optic along with positioning marks to guide surgeons in lens orientation. The posterior surface is bifocal with a diffractive structure that has smooth steps to reduce light scatter. The lens features a power add of +3.75 D and distributes light asymmetrically, 65% for far and 35% for near, which helps improve intermediate vision while also reducing halos and glare at night.

Surgical considerations

Dr. Breyer noted that optimal results with the IOL require true MICS surgery with an incision that must remain <2 mm at the end of IOL implantation. His preference is to use a particular phacoemulsification platform (Oertli, with the CO-MICS 2 tip). which allows CO-MICS through a 1.6- to 1.8-mm incision.

"The CO-MICS procedure is astigmatically neutral and, therefore, optimizes the predictability and precision of phacorefractive surgery," Dr. Breyer said. "It also minimizes induction of aberrations.

"In contrast to bimanual sleeveless MICS, monomanual CO-MICS has no intra- or postoperative leakage problems, has better fluidics and phacodynamics, and [has] less postocclusional surge," he said.

"Achieving an emmetropic outcome is also critical, and so optical biometry (IOLMaster, Carl Zeiss Meditec) should be used for axial length measurements because of its high precision," Dr. Breyer added.

Results from 11 patients who underwent bilateral CO-MICS with implantation of the IOL demonstrate the excellent outcomes achieved using this combination approach to phacorefractive surgery, even in patients with high astigmatism, he said. Excluding one patient after keratoplasty and another with amblyopia, distance vision equivalent to or better than that required for legal driving without glasses in Germany was achieved in all of the remaining patients, and they were able to read a newspaper without glasses.

Results of a patient questionnaire showed high satisfaction. Only one patient reported wearing glasses at nighttime for driving, noting that he felt more comfortable. All 11 patients responded "yes" to questions asking whether the IOL met their expectations and if they would recommend the lens to a relative. All patients were offered LASIK at no charge to improve their uncorrected visual acuity, and all declined.

"The ability to avoid a bioptics procedure is an enormous benefit of this approach to phacorefractive surgery with CO-MICS and implantation of this toric bifocal IOL," Dr. Breyer said.

Although he said he would not recommend this IOL for older patients or in eyes that have underogne penetrating keratoplasty, the 80-year-old patient with amblyopia was very happy with the outcome after surgery, Dr. Breyer said.

Providing a few surgical tips, Dr. Breyer said that reference marks should be placed on the eye with the patient sitting upright. He encouraged surgeons to take the time to create a perfect capsulorhexis, measuring about 6 mm and perfectly centered. If the capsulorhexis is too small, the IOL position can shift postoperatively, he said.

He also recommended performing extensive hydrodissection to minimize intraoperative stress on the zonules, taking into account that alignment of the IOL is associated with some zonular stress.

Dr. Breyer noted that he does not use viscoelastic for the implantation as to avoid the potential for lens rotation when the viscoelastic is removed at the end of the case.

An injector system (Acri.Shooter, Carl Zeiss Meditec) for implanting the IOL is a push-type device that is easy to use and allows surgeons to fixate the globe with their second hand, he said. Although the IOL is not ultra-thin, it readily compresses and fits through incisions as small as 1.6 mm, Dr. Breyer added.