Aberrometer helpful to guide LRIs

San Francisco-Limbal relaxing incisions (LRIs) have been recognized as an effective tool in reducing corneal astigmatism at least since the 1990s. Surgeons have also recognized that preoperative measurements and surgical plans do not always provide the best possible results.

The latest generation of intraoperative aberrometry promises to improve the accuracy and the clinical benefits of LRI by titrating the length and depth of incisions during the procedure. A prospective case analysis suggests that intraoperative refractive measurements can improve LRI results as promised.

“We have seen that the accuracy of LRIs can be improved with intraoperative titration,” said Kerry Assil, MD, Assil Eye Institute, Los Angeles. “Intraoperative data capture enables the surgeon to reduce pre-existing astigmatism more effectively without the need for postoperative enhancements.”

Dr. Assil presented a prospective case analysis of patients who were scheduled to undergo cataract surgery. The patients in the series had pre-existing astigmatism of 1.27 D +/- 0.71 D. All were scheduled for LRI based on pre-surgical measurements and planning.

During the surgery, surgeons placed the LRIs based on the preoperative plan. The initial incisions were followed by evaluation with the ORA System (WaveTec Vision), which includes intraoperative refractive measurement, to confirm the level of astigmatism correction and to titrate the LRIs if necessary.

The system performed as expected, delivering better than expected results compared with conventional LRIs. At 1 month after surgery, the mean residual astigmatism was 0.41 D, =/- 0.49D. Nearly three-quarters of the eyes, 74, had residual cylinder of less than 0.50 D while 90% had residual cylinder of less than 1 D.

Experience has shown that the ORA system is not perfect, Dr. Assil said. It is possible to overcorrect by relying entirely on the software.

“Any time I get to within 2/3 of cylinder, I stop,” he said. “We typically see a little more improvement over time than we get on the table.”

Overall, he said the system is both predictable and reliable. Results are stable at least over the first 30 days, but longer-term stability evaluations will have to wait for longer-term data.

For more articles in this issue of Ophthalmology Times Conference Brief,click here.