Intraocular lens image quality evaluated in analysis

October 1, 2010

Findings from bench model studies measuring higher-order aberrations and near, intermediate, and distance image quality of presbyopia-correcting IOLs provide further insight on the clinical performance of the available implants.

Rochester, NY-Findings from bench model studies measuring higher-order aberrations (HOAs) and near, intermediate, and distance image quality of presbyopia-correcting IOLs provide further insight on the clinical performance of the available implants, said Scott M. MacRae, MD.

Measurements were obtained using different pupil sizes (3, 4, and 5 mm) and to evaluate the effects of lens decentration (range 0 to 700 µm in 100-µm increments) on image quality and of astigmatism on image quality and depth of field.

"This information should allow surgeons to understand better the strengths and weaknesses of the various presbyopia-correcting IOLs and the conditions where they are likely to perform optimally," said Dr. MacRae, professor of ophthalmology, University of Rochester School of Medicine, Rochester, NY.

"There is concern that decentration may confound aberrations, particularly with aspheric and multifocal IOLs," he added. "The data from this study are reassuring, [because] they indicate no adverse effect on image quality even with a moderate amount of decentration that exceeds the 200- to 300-µm level typically encountered clinically. We did not evaluate the effect of tilt, which may confound things."

HOAs were measured using a Shack-Hartmann-type wavefront sensor that has 6,197 lenslets per 6 mm pupil.

"The resolution of this instrument is about 6-fold higher than the most sensitive commercially available wavefront aberrometer and allowed us to assess better the HOA profile of the premium IOLs," Dr. MacRae said. The wavefront results showed, as expected, that HOAs increased with increasing pupil size with all of the IOLs tested. At the 3-mm pupil size, the ReZoom lens stood out with a higher level of HOAs.