Intraoperative aberrometry providing ‘tighter’ outcomes

May 9, 2016

“As we all know, errors in those initial measurements can have a negative effect on refractive outcomes,” Robert J. Cionni, MD, said. “Our goal is to get it right the first time.”

New Orleans-Improvements in cataract surgery techniques, devices, and measurement tools have come hand in hand with increased expectations by patients for “perfect” surgery with no complications and no need for enhancements.

But predicting a patient’s eventual refractive outcome has still been somewhat of a guessing game, said Robert J. Cionni, MD.

Interoperative aberrometry can improve surgical outcomes and reduce the likelihood of needing to perform enhancements, said Dr. Cionni during ASCRS 2016.

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When calculating IOL powers for primary cataract surgery, most surgeons will use manual or optical biometry (and most use the latter) during preoperative evaluations.

“As we all know, errors in those initial measurements can have a negative effect on refractive outcomes,” Dr. Cionni said. “Our goal is to get it right the first time.”

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Intraoperative aberrometry has been used successfully to improve cataract outcomes in post-refractive surgery eyes, and many surgeons have begun incorporating the technology into “standard” cataract procedures.

Dr. Cionni evaluated the postoperative mean absolute value of predicted error (MAVPE) and absolute prediction error distribution after surgical procedures using intraoperative aberrometry (ORA, Alcon Laboratories) to guide IOL power selection.

All eyes were evaluated about 21 to 35 days after surgery and all eyes underwent surgery with the VerifEye or VerifEye Plus system.

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“This was a prospective, multicenter, masked study,” Dr. Cionni said, where readers were masked to both lens type and surgical technique (e.g., corneal relaxing incisions). The ORA is designed to perform aphakic and pseudophakic measurements in real time to help ensure the correct IOL power was chosen. The system captures sphere, cylinder, and axis information in seconds and conveys the data to the surgeon.

The ORA uses an infrared light and Talbot-Moiré interferometry optimized for the aphakic state to perform a “whole eye” assessment of the optical system. The device is capable of capturing 40 measurements in less than a few minutes, and displays the scans in sequence. The device then combines and analyzes data from the central 4 mm to determine the optimal IOL power for the eye.

In complicated cases, it has been reported the aphakic measurements produce a different suggested IOL power than preoperative measurements.

Study outcomes

 

Study outcomes

In this study, “we used standard inclusion and exclusionary criteria,” Dr. Cionni said, and evaluated 162 eyes. Data related to both the preoperative IOL power and predicted postoperative spherical equivalent and postoperative mean absolute value of the prediction error were collected and analyzed.

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“There were a host of different lenses implanted in these eyes, but the most commonly used implant was the SN60WF,” he said.

The MAVPE preoperative power was 0.35D (±0.37 D) but using the ORA resulted in an MAVPE of 0.29D (±0.26 D).

“The results were much tighter with intraoperative aberrometry,” Dr. Cionni said, noting the differences reached statistical significance.

Dr. Cionni also places more emphasis on the distribution to analyze outcomes, he said.

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In this study, the absolute preoperative prediction error distributions was also much better in the intraoperative aberrometry group than in the preoperative evaluation group: 85% of the ORA group were within 0.5D of target versus 76% in the preoperative group, and 57% of the ORA group were within 0.25D of target versus 46% in the preoperative group.

“At 0.5 D, this difference was statistically significant,” Dr. Cionni said.

However, the differences between the two groups diminished when results were further from target: 96% versus 90% at 0.75 D from target, and 97% in both groups 1.0 D from target.

While the differences may not seem like a lot, it translates to an additional nine patients out of every 40 who would need an enhancement of some sort, he said.

“That gets translated into patient dissatisfaction,” he said. “When those nine patients go back home and people ask them about their surgery, they’ll say: ‘Dr. Cionni got it right, but it took him two tries.’ Is that what you want your patients saying?”

In short, he said the distribution shifted to improved outcomes with intraoperative aberrometry compared with traditional preoperative power calculations.

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Dr. Cionni reported a financial interest with Alcon Laboratories.