Wavefront sheds light on changes after blepharoplasty

June 15, 2005

Sarasota, FL—Wavefront measurements may be useful in quantifying visual changes after upper blepharoplasty surgery, said William J. Lahners, MD, in private practice with the Center for Sight, Sarasota, FL. Dr. Lahners conducted a small study of this hypothesis in his practice.

Upper lid blepharoplasty is a common technique used to rehabilitate upper lid contour and function, and subjective visual changes following the procedure are common. While astigmatic changes have been reported, they are typically associated with a stable Snellen acuity, he said.

"Subjective visual performance is affected by higher-order aberrations, and wavefront technology has evolved as a means of identifying and quantifying these distortions. Our hypothesis was that upper blepharoplasty causes corneal changes detectable by wavefront analysis, and that use of this technology might help explain some of the subjective visual complaints," Dr. Lahners said.

The wavefront measurements were obtained preoperatively and 3 months postoperatively using the Alcon LADARWave CustomCornea Hartmann Shack aberrometer. The aberrations evaluated were total root mean square aberrations, total higher-order aberrations, wavefront astigmatism, vertical and horizontal coma, total coma, spherical aberrations, and "other," a category that included remaining higher-order terms such as trefoil, tetrafoil, and secondary astigmatism. Preoperative and postoperative values were compared using a two-tailed paired t-test. Each data set was a composite of five wavefront measurements.

All measurements were obtained at the same pupil size in undilated eyes.

"This is absolutely critical when comparing wavefront error information," Dr. Lahners said. "In order to achieve this, we took all the raw data that were obtained and standardized them to the same pupil size."

The smallest pupil size in this study was 3.5 mm. To include all 48 eyes, all data were calculated at this size.

"We saw no statistically significant differences between the wavefronts pre- and postoperatively following blepharoplasty (p > 0.05 for all variables)," Dr. Lahners said.

To increase the sensitivity of the study, the investigators recalculated the data at 5.0-mm pupil sizes, which allowed them to include 18 eyes.

"While there were more differences seen, again we saw no statistically significant difference in any of the measured variables. But there were individual cases where we did see some big differences," he said, noting that the most common aberration that changed was coma.

In one case, the patient, a 76-year-old male, reported better vision after blepharoplasty. The patient experienced a reduction in coma from 0.44 μm preoperatively to 0.28 μm postoperatively despite a stable refraction and a stable Snellen visual acuity.

Case 2 involved an 83-year-old female whose vision was worse after blepharoplasty despite a similar refraction and stable Snellen acuity. Her coma values increased from 0.23 μm before surgery to 0.75 μm afterward, while other variables were relatively stable.

The third case was an 81-year-old male who experienced the largest change in wavefront values in the study group. His vision improved after blepharoplasty despite an increase of about 0.3 D of astigmatism. The drop in coma was from 0.22 to 0.03 μm. The Zernike plot showed an overall flattening of most of the higher-order aberrations, which might explain the outcome, Dr. Lahners said.