Comparing Lower- and Higher-Order Aberrations: Zywave® II Hartmann-Shack Wavefront Aberrometer versus Peramis Pyramidal Aberrometer.

Purpose: To assess the agreement between Zywave® II and Peramis CSO aberrometers for lower- and higher-order aberration (LOA and HOA) measurements on dynamic conditions without cycloplegia. Methods: In this prospective comparative study, participants aged 20-45 years were examined. Exclusion criteria included previous ocular surgery or trauma, recent contact lens wear, and any ocular or systemic diseases. Each device was operated by an experienced operator who remained blind to the data obtained from the other aberrometer. We compared LOA measurements and the root mean square (RMS) of coma, spherical aberration, and total third- and fourth-order HOAs between the two devices, and the optical zone for measuring HOAs was the same in both the devices. Results: In the study involving 42 eyes of 21 participants (52.4%, female), excellent agreement was observed in LOAs (sphere and cylinder) for both the right and left eyes, with intraclass correlation coefficients of 0.96 and 0.95, respectively, using a 6 mm pupil. In addition, good-to-excellent reliability was reported for the agreement between the two devices in total HOA (t.HOA) and the RMS error of the total aberration, for pupil sizes of 5 mm and 6 mm. However, there was poor agreement between the two devices for third- and fourth-order aberrations in both the pupil sizes. Conclusions: The present study demonstrates agreement between the Zywave® II and Peramis® aberrometers in measuring sphere, cylinder, t.HOA, and total aberration. Nevertheless, notable differences were identified in third- and fourth-order aberrations, suggesting that specific measurements may not consistently align between devices, and these values should not be considered interchangeable.