New toric IOL provides stable, good vision after cataract surgery

Lens improves the image quality and is an ideal implant for microincision cataract surgery, surgeon says.

ROME — A new toric IOL provides good vision and spectacle independence in astigmatic cataract patients, according to the surgeon who implanted this lens during the live surgery session of the winter meeting of the European Society of Cataract and Refractive Surgeons here.

Toric IOLs have been an important advancement in cataract surgery, Alessandro Mularoni, MD, said. He told the audience that 5% to 15% of cataract patients have a preoperative astigmatism of more than 1.5 D. Uncorrected, it leads to a visual acuity of less than 20/40, to poor near vision and to the use of spectacles for both distance and near.

“Correcting the astigmatism at the time of cataract surgery can greatly improve visual results and the patient’s life quality, and toric IOLs are the safest, more predictable, reproducible and effective option. An additional advantage is that the result is achieved in one single procedure,” Dr. Mularoni said.

Increased demands

The demand for this technology has increased in recent years, concomitantly with the increased offer of toric lens models by several manufacturers, Dr. Mularoni said.

“The concept of refractive cataract surgery is gaining popularity, and more patients want to be spectacle independent,” he said, adding that toric IOLs have progressively improved their quality and stability.

Dr. Mularoni said he has tested all currently available toric IOLs and has recently introduced the Zeiss Acri.Comfort 646 TLC in his clinical practice. Characteristics of this lens design are the aspheric profile and double toricity obtained by a symmetric distribution of the cylinder on the anterior and posterior surfaces.

“This greatly improves the image quality, as seen by comparing the [modulation transfer function] of this lens with that of monotoric lenses. This is particularly true for larger pupil diameters,” he said.

Another advantage of this lens, which is made of hydrophilic acrylic material with hydrophobic acrylic surface, is that it can be inserted through a microincision of 1.4 mm, with no induction of astigmatism. It is therefore an ideal implant for microincision cataract surgery, Dr. Mularoni said.

Stability was tested in 43 patients implanted with its ‘sister’ lens, the Acri.Smart 46S, and it appears to be good.

Alignment is a crucial step

When toric correction is involved, IOL implantation becomes the most delicate stage of cataract surgery, Dr. Mularoni said. Preoperatively, he measures the amount and axis of the astigmatism in the elevation maps obtained with Orbscan (Bausch & Lomb) or Precisio (iVIS) corneal tomography systems. Biometry is carried out with the Zeiss IOL Master.

Marking the astigmatic axis on the cornea for a correct alignment of the lens is a crucial step.

“We do it with the patient sitting at the slit lamp, using a special marker mounted on the Goldmann tonometer head. We mark the 0· to 180· meridian and, by rotating the marker, also the meridian on which we want to implant the lens. The distal end has a special design that allows peripheral marking of corneas with different curvatures,” Dr. Mularoni said.

During surgery, the implantation axis is double-checked with a Mendez ring. Postoperatively, at day 1, 7 and 30, the stability of the lens in the bag is evaluated using the same marker, a digital photo system and wavefront aberrometry, he said. Wavefront examination is carried out using the Nidek OPD-Scan to objectively compare corneal and internal astigmatism. – by Michela Cimberle

Alessandro Mularoni, MD, can be reached at Ospedale Maggiore, Via Largo Negrisoli 2, Bologna, Italy; e-mail: alessandro.mularoni@ausl.bologna.it. Dr. Mularoni has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.