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Toric IOL maintains uncorrected distance vision, reduces corneal astigmatism
Lens rotation up to 6 months after surgery surpassed ANSI recommendations.
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A toric iteration of an established IOL design reduced corneal astigmatism and improved uncorrected distance vision, according to a study.
The Tecnis toric IOL (Abbott Medical Optics) also exceeded American National Standards Institute (ANSI) guidelines for rotational stability, Kevin L. Waltz, OD, MD, the corresponding author, said.
“[This study] was the first FDA toric study done under the new ANSI guidelines,” Waltz told Ocular Surgery News. “The Tecnis toric met those guidelines comfortably.”
Study data were from the Investigational Device Exemption registration clinical trial submitted to the FDA.
Kevin L. Waltz
“What was most noteworthy, I think, is that this lens is based on a well-known design we’re all familiar with, the Tecnis one-piece monofocal. It goes through the same injector. It behaves the same way inside the eye. It’s an additional attribute to the lens, but there’s no hassle to using it,” Waltz said.
The study was published in Ophthalmology.
Patients and measures
The prospective, multicenter, bilateral phase 3 clinical trial comprised 269 patients who underwent cataract surgery.
A randomized control arm comprised 197 patients who required cylinder correction of 0.75 D to 1.5 D. This group included 102 patients who underwent implantation of a Tecnis ZCT150 toric IOL and 95 patients who received a Tecnis ZCB00 non-toric IOL.
An open-label arm comprised 72 patients who required cylinder correction of 1.5 D to 3.62 D; 17 patients received a Tecnis ZCT225 toric IOL, 25 patients received a Tecnis ZCT300 toric, and 30 patients received a Tecnis ZCT400 toric lens.
“In the higher amounts, everybody automatically got the astigmatism-correcting lens. In the lower amounts of astigmatism, we were using a ZCT150. That portion of the study was randomized. Some people got the astigmatism-correcting lens, some people didn’t,” Waltz said.
Uncorrected and corrected distance visual acuity, manifest refraction, IOP, keratometry, adverse events, spectacle wear and IOL rotational stability were assessed at 1 day, 1 week, and 1, 3 and 6 months postoperatively. High-resolution slit lamp digital photographs were used to evaluate lens rotation.
Examiners were masked as to which lens was implanted in each patient. Separate examiners performed slit lamp examination of axis markings on toric IOLs to ensure masking.
Outcomes and observations
Cylinder was reduced by a mean 74.53% in eyes implanted with the ZCT150 toric IOL and 31.61% in eyes that received the ZCB00 non-toric IOL; the difference was statistically significant (P < .0001).
Cylinder decreased by a mean 76.27% in the open-label arm.
Uncorrected distance visual acuity of 20/20 or better was attained in 43.6% of eyes implanted with the ZCT150 toric IOL and 23.7% of eyes implanted with the ZCB00 non-toric IOL; the difference was statistically significant (P = .0026).
Uncorrected distance visual acuity of 20/20 or better was attained in 38% of eyes in the open-label arm.
All eyes had uncorrected distance visual acuity of 20/40 or better at 6 months.
Lens rotation was 5° or less in 92.9% of toric IOL eyes from 1 to 3 months and in 94.1% from 3 to 6 months. Rotation findings surpassed the ANSI standard of 90% or more eyes having less than 5° of rotation between visits, the study said.
“What we found was that the uncorrected acuity, both distance and intermediate, was remarkably good,” Waltz said. “We’re not sure why, but with this lens we got a surprising amount of intermediate and sometimes near vision even if we were only correcting for distance. You’ll see that with toric corrections of all kinds on occasion. We got good uncorrected acuity. We got good rotational stability. We got good correction of the amount of astigmatism.”
Four lenses required repositioning.
In addition, 80.4% of patients in the randomized and open-label arms who received toric IOLs were spectacle independent at distance. – by Matt Hasson
References:
Clinical evaluation of a 1-piece intraocular lens. clinicaltrials.gov/ct2/show/NCT01098812.Waltz KL, et al. Ophthalmology. 2014;doi: 10.1016/j.ophtha.2014.06.027.
For more information:
Kevin L. Waltz, OD, MD, can be reached at Eye Surgeons of Indiana, 8103 Clear Vista Parkway, Indianapolis, IN 46256; email: kwaltz56@gmail.com.Disclosure: Waltz reports he is a consultant for Abbott Medical Optics and received payment for research performed in the study.
Perspective
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Tal Raviv, MD
As surgeons and patients alike strive for more precise refractive outcomes after cataract surgery, management of astigmatism has become a key component in achieving success.
This study presents the clinical results of the Tecnis toric IOL multicenter trial, as presented to the FDA for its U.S. approval. Waltz and colleagues show that the Tecnis toric IOL safely and effectively reduced pre-existing corneal astigmatism in patients undergoing cataract surgery. Eyes receiving a toric IOL achieved greater percentage reduction in astigmatism, less residual astigmatism and greater levels of uncorrected visual acuity than a spherical IOL control arm. The study further revealed the excellent rotational stability of the Tecnis toric IOL, with 94% of eyes rotating less than 5° within 6 months; 2.3% of eyes underwent secondary IOL rotation in the early postoperative period.
While significant reductions in astigmatism and spectacle dependence were achieved with the Tecnis toric IOL, there is always room for improvement. The study used IOLMaster (Carl Zeiss Meditec) keratometry exclusively for surgical planning. In clinical practice, most surgeons use at least two or three keratometry measurements, including auto, manual, biometry and topography, in planning. Also, since this study concluded, the importance of posterior corneal astigmatism has been elucidated and new surgical guidance systems have been introduced.
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