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Measurements vary among Shack-Hartmann aberrometers
MUNICH, Germany — A study comparing three Shack-Hartmann wavefront analyzers found variations among their measurements of patients’ higher-order aberrations, a speaker here said.
Helga Sandoval, MD, and colleagues compared wavefront measurements made using the LadarWave (Alcon), WaveScan (Visx) and the Zywave (Bausch & Lomb). She presented the results of the study here at the European Society of Cataract and Refractive Surgeons meeting.
In the study, 99 patients underwent cycloplegic refraction followed by evaluation of their higher-order aberrations using each system. A 3.5-mm optical zone was used during the measurements for both the LadarWave and the Zywave. A 4-mm optical zone was used with the WaveScan.
In the study, the WaveScan consistently measured sphere lower than either the Zywave or LadarWave, which measured sphere almost equally, according to Dr. Sandoval. The Zywave measured cylinder lower than either the WaveScan or the LadarWave, she said.
The LadarWave and the Zywave measured total root mean square (RMS) aberrations about equally, while the WaveScan consistently undermeasured total RMS values, she said.
Dr. Sandoval acknowledged that Visx advises against dilating patients’ pupils when using the WaveScan aberrometer. Because all pupils were dilated before the measurements were taken, this could have resulted in the lower readings, she said.
Dr. Sandoval said a study confirming her findings is needed. She is currently involved in a study comparing postop results among the three systems.