Comparison of Corneal Thickness Measurements by Ultrasound and Scheimpflug Photography in Eyes That Have Undergone Laser In Situ Keratomileusis

Purpose: To compare two methods of measuring central cornea thickness (CCT) in eyes that have undergone laser in situ keratomileusis (LASIK). Design: Prospective clinical trial. Methods: The corneal thickness from 104 eyes of 53 consecutive patients undergoing the one-year follow-up after LASIK was measured with both the Pentacam (Oculus, Inc, Wetzlar, Germany) and ultrasonic pachymetry. All patients were examined at one clinical setting, where first Pentacam imaging was performed by one technician and then ultrasound pachymetry was performed by a masked second technician. The results were compared. Results: The average age of the patient population was 38 years (range, 22 to 56 years) of those who underwent the one-year follow-up examination an average of 406 days (range, 264 to 579 days) after LASIK. The mean CCT measurement was 506 ± 29.5 μm (range, 454 to 574 μm) with the Pentacam topographer and 505 ± 31.7 μm (range, 433 to 576 μm) with ultrasound pachymetry. The average difference (Pentacam minus ultrasound) was 1.4 ± 10.4 μm (range, -21.8 to 23.4 μm). Conclusions: The Pentacam's CCT measurement and that of ultrasound pachymetry show good correlation. Pentacam pachymetry may be substituted for ultrasound in the post-LASIK patient.