Comparison of ocular aberrations measured by a Fourier-based Hartmann-Shack and Zernike-based Tscherning aberrometer before and after laser in situ keratomileusis.

PURPOSE: To assess agreement between a Hartmann-Shack aberrometer (Wavescan) and a Tscherning aberrometer (Wavelight Allegro Analyzer) and their respective agreement with manifest refraction before and after laser in situ keratomileusis (LASIK).

SETTING

Stanford Eye Laser Center, California, USA.

DESIGN

Prospective comparative observational study.

METHODS

Multiple readings were obtained both aberrometers preoperatively and 12 months after wavefront-guided LASIK. Sphere, cylinder, spherical equivalent (SE), defocus Z(2,0), astigmatism Z(2,2), spherical aberration Z(4,0), coma Z(3,1), trefoil Z(3,3), and total higher-order aberrations (HOAs) were compared using intraclass correlation coefficients (ICCs) (perfect agreement = 1; disagreement = 0).

RESULTS

In the 100 study eyes, preoperative agreement was good to excellent between the aberrometers for the parameters of defocus, astigmatism, and spherical aberration (ICC: 0.8, 0.9, and 0.7, respectively) but was poor for coma, trefoil, and total HOAs (ICC: 0.6, -0.2, and 0.4, respectively). At 12 months, ICCs worsened for all parameters (ICC: defocus = 0.6; astigmatism = 0.2; spherical aberration = 0.6; coma = 0.4; trefoil = -0.3; total HOAs = 0.4). Preoperative agreement of sphere, cylinder, and SE was good to excellent between the manifest refraction and both aberrometers (ICC Hartmann-Shack: 0.98, 0.95, and 0.97, respectively; ICC Tscherning: 0.97, 0.92, and 0.98, respectively). However, agreement was poor to fair between the manifest refraction and both aberrometers at 12 months (ICC Hartmann-Shack: 0.4, 0.1, and 0.4, respectively; ICC Tscherning: 0.03, 0.02, and 0.2, respectively).

CONCLUSIONS

Although some HOAs measured with both aberrometers agreed preoperatively, such agreement might not persist after LASIK. Spherocylinder measurements with both aberrometers seemed to agree closely with the manifest refraction before LASIK, but not at 12 months.

FINANCIAL DISCLOSURE: Dr. Manche has equity in Calhoun Vision, Inc., Krypton Vision, Seros Medical, LLC, and Veralas and is a consultant to Best Doctors, Gerson Lehrman Group.