Different aberrometry technologies not always comparable

Houston-Results from a clinical practice study directly comparing wavefront analysis using two different technologies-ray tracing (Visual Function Analyzer version 1.1,VFA, Tracey Technologies) and a Hartmann-Shack-type aberrometer (WaveScan Version 3.01, VISX)-show that the machines are in good agreement in their measurements of refraction and root mean square (RMS) values for both lower-order and total aberrations, but not in their measurement of higher-order aberrations, according to Rahul T. Pandit, MD.