Image-guided planning system helps cataract surgeons hit the mark with toric IOLs

Take-home message: Toric IOL implantation using a proprietary image-guided system for planning and executing cataract surgery results in good accuracy to cylinder and MRSE targets.

By Cheryl Guttman Krader; Reviewed by Stephen S. Lane, MD

Minneapolis-Use of a new proprietary image-guided system for surgical planning (Verion Image Guided System, Alcon Laboratories) leads to excellent refractive and functional results in patients undergoing phacoemulsification with toric IOL implantation.

Such are the findings according to a prospective multicenter study reported by Stephen S. Lane, MD, medical director, Associated Eye Care, and adjunct clinical professor, University of Minnesota, Minneapolis, Minneapolis.

The study was performed at five centers and included 102 eyes of 102 patients with a single-piece, hydrophobic, acrylic aspheric toric IOL (AcrySof IQ Toric IOL, Alcon Laboratories) implanted. Mean preoperative astigmatism was 1.645 D, but the range was 0.29 to 9.69 D, and about one-fifth of eyes had more than 2.00 D of preoperative astigmatism.

Outcomes analyses

Outcomes were analyzed using data collected at 3 months after surgery. The primary efficacy analysis showed that residual refractive cylinder was ≤0.50 D in 72% of eyes and 90% were left with ≤0.75 D of refractive cylinder.

However, according to the preoperative calculations, only 81% of eyes were anticipated to have ≤0.50 D of residual cylinder while 91.4% were expected to have ≤0.75 D of residual cylinder. Calculations performed using that information showed excellent accuracy of the astigmatism outcomes as residual refractive cylinder was within 0.5 D of target in 88.4% of eyes and within 0.75 D of target in 98.7%.

Secondary outcome analyses showed good MRSE accuracy and improvements in distance uncorrected and best-corrected visual acuity (UCDVA and BCDVA), Dr. Lane said.

Use of guidance system allows for accurate “marking” of the appropriate meridian to place the toric IOL and as a consequence, leads to superior visual acuity results, he noted.

“This system obviates the need for manual ink marking of the eye prior to surgery, which can be quite inaccurate as the ink ‘bleeds,’ not to mention the time necessary to make the marks,” he said.

The convenience and accuracy makes the digital marker at the microscope a better process, he noted.

Dr. Lane’s co-investigators were Kerry Solomon, MD, Charleston, SC; Stephen Slade, Houston; Robert Cionni, MD, Salt Lake City; and Philippe Crozafon, MD, Nice, France and Genoa, Italy.

The image-guided surgical planning system used in the study is designed to optimize refractive outcomes. It features imaging (Verion Measurement Module), clinical planning (Verion Vision Planner), and surgical guidance tools (Verion Digital Marker). The imaging tool obtains ocular surface measurements, including keratometry, and a digital image of the eye for intraoperative cyclorotation registration.

The planning software takes the preoperative data and does IOL power calculations using modern advanced formulas while giving the surgeon the option to correct astigmatism with a toric IOL alone, arcuate incisions alone, or a combination of the two.

The imaging and planning information can also be used to create a template for guiding placement of primary, secondary, and arcuate incisions, placement of the IOL, and for the creation of the capsulorhexis.

“The template is electronically transferred to the surgical microscope, thereby avoiding transcription errors,” Dr. Lane said. “The seamless transfer of real-time registration and tracking information optimizes and streamlines the entire process.”

More outcomes data

The analysis of MRSE accuracy at 3 months showed 70% of eyes were within 0.50 D of target, 87% were ≤0.75 D, and 91.2% were ≤1.00.

UCDVA was 20/20 or better in about one-fourth of eyes, while nearly two-thirds achieved 20/25 or better. No eyes lost BCDVA, and it was 20/32 or better in all eyes and 20/20 or better in almost two-thirds of the cases.

Spherical equivalent (SE) at 3 months after surgery was ≤0.50 D in 68% of eyes, ≤0.75 D in 81% and ≤1.00 D in 87%. Dr. Lane also presented data from analysis of defocus equivalent outcomes, noting that according to Jack Holladay, MD, defocus equivalent correlates better with UCVA than SE.

In the defocus equivalent analysis, 50% of eyes had ≤0.50 D of defocus equivalent, 69% had ≤0.75 D, and 77% were ≤1.00 D.

“In summary, treatment of pre-existing astigmatism by implantation of toric IOLs using the Verion Measurement Module, Vision Planner, and Digital Marker M yielded excellent 3 month outcomes, including low residual refractive cylinder and good MRSE accuracy,” Dr. Lane concluded.

Stephen S. Lane, MD

E: sslane@associatedeyecare.com

This article was adapted from Dr. Lane’s presentation at the 2015 meeting of the American Society of Cataract and Refractive Surgery. Dr. Lane is a consultant to Alcon Laboratories.