Effect of axial length intraoperative WF aberrometry measurements

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Results of a retrospective analysis of eyes undergoing cataract surgery with intraoperative guidance of IOL power selection using wavefront aberrometry (ORA System, WaveTec Vision) show it has value for improving refractive predictability, especially in long and short eyes.

San Francisco-Use of intraoperative wavefront aberrometry (ORA System, WaveTec Vision) improves refractive outcomes in cataract surgery. Its use is of particular benefit when operating on shorter and longer eyes for which accurate IOL power calculation is more challenging, according to the results of a retrospective study presented by Timothy N. Peters, MD.

“The modern formulas that we use to calculate IOL power perform consistently in providing reasonable outcomes for eyes with ‘normal’ axial length,” said Dr. Peters, private practice, Portsmouth, NH. “However, they have poorer reliability for accurately determining IOL power in eyes at the ends of the axial length spectrum.

“Analyses based on a large population of eyes operated on with intraoperative aberrometry indicate that this technology adds value in all cases and especially for the non-average eye,” said Dr. Peters at the annual meeting of the American Society of Cataract and Refractive Surgery. “In my experience, the intraoperative aphakic reading generally confirms the lens power I have chosen preoperatively based on standard calculations, but its use has led me to change the plan more than half the time in longer and shorter eyes. Postoperative analyses show that the change was consistently in the right direction.”

The effect of intraoperative wavefront aberrometry on refractive outcome predictability was investigated using data from 2,200 eyes in the manufacturer’s database. The results were determined for the entire cohort and for subgroups of short (<22.5 mm) and long eyes (>26.5 mm).

For the entire population, the overall mean absolute value prediction error (MAVPE) was 0.33 D ± 0.29 D. SE in about half of the eyes was within 0.25 D of the intended preoperative predicted SE, 79% were ± 0.50 D, 93% were ± 0.75 D, and 97% were ± 1 D.

Prediction errors and standard deviations of the means were just slightly higher in both subgroups of eyes with extreme axial lengths. The MAVPE was 0.39 D ± 0.35 D for short eyes and 0.36 ± 0.32 D for the long eyes; in both groups ~75% were within 0.50 D of the formula predicted SE.

“Prediction errors should be further reduced by software updates that optimize lens coefficients by axial length group. In fact, my personal MAVPE for long and short eyes operated on without ORA was 0.6 D, but with a personalization of my ORA outcomes, my MAVPE in these eyes is just 0.3 D,” Dr. Peters said.

Dr. Peters said he offers intraoperative wavefront aberrometry to all patients undergoing cataract surgery while counseling them on its benefits and associated fee. Currently, about 80% of patients opt for its use.

Timothy N. Peters, MD

E: TPeters@EyesightNH.com

Dr. Peters has no relevant financial interest to disclose.

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