Abstract:

Objective   To verify the consistency between the results of Pentacam and ultrasonic pachymetry, and between that of Pentacam and traditional corneal topography; to evaluate the influence of surgery type, AD, AD/CT, RBT and IOP on the changes of posterior cornear after excimer laser photorefractive keratectomy by Pentacam. Methods  Choose myopic patients who underwent excimer laser refractive surgery during January 2010 to June 2010 in our hospital. Certain amount was included for each group of analysis. Pentacam, ultrasonic pachymetry, traditional corneal topography and other tests necessary for the surgery like IOP were taken. Patients were divided into the LASIK and LASEK groups according to the type of surgery. For every patient during the surgery, AD and RBT were documented and AD/CT was calculated. 8~12 weeks after the surgery, Pentacam was redone. Results   ① Consistence rate of Pentacam and ultrasonic pachymetry for CCT was 97.62%，and poisson correlation coefficient was 0.96；② Consistence rate of Pentacam and traditional corneal topography for AverK was 100%，and poisson correlation coefficient 0.98； ③ Mean value of posteror cornea elevation for patients underwent LASIK surgery was 2.46μm，while that of patients underwent LASEK was 0.6μm. In both groups forward shift rised with the increase of AD and AD/CT, declined with the increase of RBT, and showed no correlation with IOP. Conclusions   ① Pentacam is consistent with ultrasonic pachymetry for measuring CCT. As a noninvasive novel inventure, Pentacam is suitable for pre-operative tests for excimer laser photorefractive keratectomy. ② For healthy patients, Pentacam could replace traditional corneal topography. More results of the anterior segment of the eye could be got other than K vales by using Pentacam. ③ Minor posteror cornea elevation exists after both LASEK and LASIK. And the former is more subtle. ④ The degree of posteror cornea elevation is in positive relation with AD and AD/CT, negative with RBT, and no relation with IOP.

Key words:  Pentacam rotationg scheimpflug camera; Ultrasonography; Cornea