Toric IOLs perform well with microincision surgery

Now that MICS has reduced the induction of surgical astigmatism, postoperative results can aim for nearly full cylinder compensation.

Pierre-Jean Pisella

ISTANBUL — Toric IOLs are an important step forward in refractive cataract surgery, providing effective solutions for patients with corneal astigmatism.

“Approximately 8% of the eyes we operate for cataract have more than 2 D astigmatism, and 16% have 1.5 D,” Pierre-Jean Pisella, MD, said at the winter meeting of the European Society of Cataract and Refractive Surgeons here.

Now that microincision cataract surgery techniques have significantly reduced the induction of surgical astigmatism, Dr. Pisella said, toric IOLs are sensible because postoperative results can aim for nearly full cylinder compensation.

Study results

A study conducted by Dr. Pisella and colleagues showed that after 1.8-mm incision cataract surgery, 60% of patients had less than 0.5 D of surgically induced astigmatism and only 10% had more than 1 D. Previous data published by Alió and colleagues showed that standard 3-mm incisions produced more than 1 D of astigmatism in 50% of eyes.

Among new toric options, the Lentis Tplus IOL (Topcon/Oculentis) can be implanted through a small, 1.8-mm incision. It is a biconvex, aspheric one-piece acrylic lens that can be tailored to suit individual corneal irregularities based on preoperative topography.

Dr. Pisella presented the preliminary results of a study involving 13 eyes of eight patients who underwent cataract implantation through a 1.8-mm incision. The Lentis L313T IOL was implanted to compensate for preoperative corneal astigmatism. Evaluation of corneal topography, corneal higher-order aberrations and objective contrast sensitivity with the Optical Quality Analysis System demonstrated good visual and optic performance of the lens. Mean postoperative refractive cylinder was close to 0.5 D, and uncorrected visual acuity at 6 months was 20/20 or better in 50% of eyes and at least 20/32 in 100% of eyes.

No decrease in quality of vision was observed, and visual quality on the whole was as good as with standard monofocal IOLs.

“Customized manufacturing leads to unequalled precision and visual quality but requires exact positioning and perfect stability in the eye,” Dr. Pisella said.

There is still some rotation of the lens that needs to be controlled better, he said. However, mean rotation was less than 5° at 6 months, and in no case was it more than 10°.

Additional option

Another toric IOL, the Basis Z (1stQ), is currently undergoing a prospective study to evaluate the feasibility of implantation through a 1.8-mm incision.

This lens, presented at the meeting by Detlef Holland, MD, is an injectable one-piece hydrophilic acrylic implant with Z-haptics.

“We have so far implanted 117 Basis Z IOLs,” Dr. Holland said. “In a previous study, we evaluated the performance of this lens with standard cataract surgery in 41 eyes of 32 patients. Mean postoperative cylinder was 0.5 D, and we achieved a mean uncorrected visual acuity of 20/25 and a best corrected visual acuity of 20/20.”

Mean deviation from the planned axial localization was 3°.

“I had to reposition the lens in three cases due to rotation, but this happened at the beginning of my learning curve. I learned how crucial the capsulorrhexis is in this respect. After using a 5-mm rhexis, which precisely overlapped the optic by 1 mm, rotation no longer occurred. I also slowed down my technique toward the end of surgery, particularly when I removed the viscoelastic,” Dr. Holland said.

Long-term follow-up will be necessary with both of these lenses to evaluate their performance with respect to posterior capsular opacification. – by Michela Cimberle

References:

• Alió J, Rodríguez-Prats JL, Galal A, Ramzy M. Outcomes of microincision cataract surgery versus coaxial phacoemulsification. Ophthalmology. 2005;112(11):1997-2003.
• Nochez Y, Majzoub S, Pisella PJ. Corneal aberration integrity after microincision cataract surgery: prerequisite condition for prediction of total ocular aberrations. Br J Ophthalmol. 2010;94(5):661-663.

• Pierre-Jean Pisella, MD, can be reached at CHU Bretonneau, 2 Bd Tonnellé, 37000 Tours, France; 33247474733; fax: +33247478136; email: pj.pisella@chu-tours.fr.
• Disclosures: Dr. Holland has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned. Dr. Pisella has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.

Rudy Nuijts

Toric IOLs are a safe and effective new option for astigmatic patients who undergo cataract surgery. In general, toric IOL implantation now results in a high level of uncorrected distance visual acuity and low level of residual refractive astigmatism. It is currently unclear whether smaller incisions, up to 1.8 mm, result in lower levels of surgically induced astigmatism compared to 2.2- and 2.4-mm incisions. Randomized clinical trials are needed to determine whether toric IOL implantation combined with small incision surgery results in higher levels of patient satisfaction with uncorrected distance vision.

— Rudy Nuijts, MD
University Hospital, Maastricht, Netherlands
Disclosure: Dr. Nuijts is a consultant for Alcon and has
received lecture fees and grant support from the company.
He has received a patent royalty from ASICO.