How image-guided systems benefit surgical planning

April 21, 2015

Three surgeons all presented portions of an overall study to evaluate an image-guided system for surgical planning and digital alignment.

San Diego-Three separate papers from one study have shown low residual refractive cylinder, good accuracy to target, and refractive outcomes when using the image-guided system for surgical planning on patients with different IOL platforms.

Three surgeons-Stephen G. Slade, MD, Houston; Kerry D. Solomon, MD, Mount Pleasant, SC; and Stephen S. Lane, MD, Bloomington, MN-all presented portions of their overall study to evaluate the Verion (Alcon Laboratories) image-guided system for surgical planning and digital alignment.

Dr. Slade presented results from the open-label, prospective, nonrandomized, multicenter study in 188 eyes that underwent femtosecond laser-assisted cataract removal (LenSx) using phacoemulsification; any preoperative astigmatism was treated with astigmatic keratotomy (AK). Group 1 (n = 88) was implanted with a monofocal lens, and Group 2 (n = 100) with a multifocal lens.

At 3 months follow-up, 62% and 83% had residual refractive cylinder of ≤0.50 D and ≤0.75 D, respectively, in the multifocal lens group.

At the same follow-up, 71% and 88% in the monofocal group had a residual refractive cylinder of ≤0.50 and ≤0.75 D, respectively. In the monofocal lens group, 77% had a manifest refractive spherical equivalent (MRSE) of ≤0.50 D and 98% were within ≤0.75 D accuracy. In the multifocal group, 82% had MRSE of ≤0.50 D and 94% were within ≤0.75 D accuracy.

Dr. Slade did not have an explanation for why the multifocal group seemed to perform better statistically.

Next: Results deepen

 

Exploratory efficacy results show a cumulative best-corrected distance visual acuity of 20/30 was achieved in 98.9% of the monofocal group and in 98% of the multifocal group, Dr. Slade said.

“This part of the study shows we’re able to achieve good accuracy and refractive outcomes when we use an image-guided system for surgical planning on patients with different IOL platforms,” Dr. Slade said.

Dr. Solomon evaluated 110 eyes from 110 patients undergoing toric IOL implantation, also using the Verion system for surgical planning and digital marking. Patients in this part of the study had an average of 1.8 D cylinder to correct, and most of the astigmatism was with the rule (almost 50%).

In this part of the study, 44% of patients had no residual refractive cylinder at 3 months postoperative, and 80% had MRSE accuracy to target of ≤0.50 D, with 92% within ≤0.75 D accuracy.

Further, 75% of patients had 0.5 D or less of residual refractive cylinder, and 86% had less than 0.75 D, he said.

“Manual diagnostic devices and IOL power calculation formulas can result in a wide variability in refractive outcomes,” he said.

He added during a question-and-answer period that the Verion calculator is slightly different from Alcon’s online toric calculator.

“The surgical planner allows for a good variety of marking, but it does not take into account posterior corneal astigmatism,” Dr. Solomon said. “Eventually, we will have a system that does it all in one unit.”

In Dr. Lane’s presentation, he evaluated 102 eyes with preoperative astigmatism ranging from 0.29 to 9.69 D, with the majority of astigmatism against-the-rule.

Next: Conclusion

 

In this part of the study, 72% and 90.2% had residual refractive cylinder of ≤0.50D and ≤0.75 D at 3 months postoperative follow-up, respectively (p < 0.0001). Mean residual refractive cylinder was 0.45 D (SD ± 0.45). Of the patients, 70% had postoperative MRSE accuracy to target of ≤0.50 D and 87% were within ≤0.75D accuracy (p <0.0001) at 3 months postop follow-up. Mean MRSE accuracy to target at 0.07D (SD ± 0.5).

If, however, the results are analyzed with the defocus equivalent at 3 months, 50% of the eyes were 20/30 or better. (Dr. Lane defined defocus equivalent as being calculated with absolute sphere plus half of absolute cylinder.)

“That we had 72% within 0.5 D is substantially better than the 50% reported in the literature,” he said.