Dynamic stimulation aberrometry expands diagnostic spectrum

Dynamic stimulation aberrometry (DSA) is an interesting alternative that enlarges the diagnostic spectrum by enabling objective measurement of range of accommodation after implantation of accommodating IOLs and in other instances, said Matthias Elling, MD, of Ruhr University Eye Hospital, Bochum, Germany.

He and colleagues conducted a study of 30 healthy phakic eyes and 15 healthy pseudophakic eyes (including eyes in which accommodating IOLs had been implanted) to determine the accuracy, reproducibility, and intra- and inter-observer reliability of DSA.

"DSA enables binocular dynamic accommodation stimulation during regular wavefront measurements," Dr. Elling said. All measurements in this study were made with a proprietary aberrometer using Hartmann-Shack wavefront sensing (WASCA Analyzer, Carl Zeiss Meditec) that had been upgraded with software (Profile Analyzer, Optana Medizintechnik) to permit DSA.

Patients focused on a distance target (3 m away) for 3 seconds, then focused on a near target (5 m away) for 3 seconds, and then focused again on a distance target for 3 seconds. During the total of 9 seconds, 300 single measurements were performed. The researchers analyzed the dynamic course of changes in lower-order aberrations (sphere and astigmatism) and higher-order aberrations.

To analyze intra-observer reliability, one examiner measured each eye five times.

"This collective contains 20 healthy phakic eyes and eight healthy pseudophakic eyes," Dr. Elling said.

To evaluate inter-observer reliability, each eye was measured five times, and results were compared."This collective included 10 healthy phakic eyes and eight pseudophakic eyes," Dr. Elling said.Reproducibility and accuracy also were measured.

Results indicate that "DSA allows objective and observer-independent measurements of changes in accommodation in phakic and pseudophakic eyes," Dr. Elling said. "This method provides a high degree of accuracy in all measurements. We recommend use of this technology in addition to the common psychophysical examinations to attain objective information on the range of accommodation, sphere, cylinder, and pupil size."