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Keratometry for intraocular lens power calculation using Orbscan II in eyes with laser in situ keratomileusis
Arthur C K Cheng1, Dennis S C Lam
1Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, University Eye Center, Hong Kong Eye Hospital, Kowloon, Hong Kong. arthurcheng@cuhk.edu.hk
Purpose:
To compare the results of comeal keratometry after laser in situ keratomileusis (LASIK) obtained by the Gaussian optics formula and the clinical history method.
Methods:
Sixty-one consecutive patients (121 eyes) who had undergone LASIK were recruited in this retrospective case-controlled study. The K-value obtained from the Gaussian optics formula (CalK) based on postoperative corneal topography by Orbscan II (Bausch & Lomb, Rochester, NY) and ultrasound pachymetry was compared with that obtained from the clinical history method (estK). Keratometry measured by these two methods was compared using the paired sample t test and Pearson correlation coefficient.
Results:
A high correlation was noted between K-value obtained by the clinical history method and the Gaussian optics formula (R = 0.97, P < .001). The mean difference between the two methods is 0.13 diopters (P = .06).
Conclusions:
K reading derived from the Gaussian optics formula correlated closely to that obtained from the clinical history method and would be especially useful in patients with no preoperative LASIK treatment data.