Central corneal thickness measurements using Orbscan II, Visante, ultrasound, and Pentacam pachymetry after laser in situ keratomileusis for myopia

Abstract

Purpose: To compare corneal pachymetry assessment using 4 measurement methods in eyes after laser in situ keratomileusis (LASIK) for myopia. Setting: Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Hong Kong SAR. Methods: Fifty-two consecutive patients (103 eyes) who had LASIK for the correction of myopia had Orbscan II (Bausch & Lomb), Visante (Carl Zeiss Meditec), Pentacam (Oculus, Inc.), and ultrasound (US) pachymetry (Sonomed, 200P) 6 months after surgery. Data were analyzed using the paired sample t test, Bland-Altman plots, and linear regression. Results: The mean postoperative pachymetry measured by US, Orbscan (0.89 acoustic factor), Pentacam, and Visante pachymetry were 438.2 μm ± 41.18 (SD), 435.17 ± 49.63 μm, 430.66 ± 40.23 μm, and 426.56 ± 41.6 μm, respectively. Compared with the US measurement, Pentacam and Visante measurements significantly underestimated corneal thickness by a mean of 7.54 ± 15.06 μm (P<.01) and 11.64 ± 12.87 μm (P<.01), respectively. There was no statistically significant difference between US and Orbscan measurements. Conclusion: Pentacam and Visante measurements of corneal thickness 6 months after LASIK were significantly less than those obtained using Orbscan and US pachymetry, although all 4 measurement methods showed a high correlation with each other. © 2007 ASCRS and ESCRS.