Comparison of corneal endothelial cell density with two non-contact specular microscopes before and after refractive surgery for the correction of myopia

Abstract

Objective To compare corneal endothelial cell density with two non-contact specular microscopes before and after refractive surgery for myopia. Methods The data of 182 eyes of 91 cases with myopia were selected. All cases were examined with SP-1P and EM-3000 non-contact corneal endothelial microscopes respectively. Among them, 67 eyes of 34 cases with myopia underwent SMILE. The corneal endothelial cell density were measured with two corneal endothelial microscopes 1 week postoperatively. The speculation microscopes measurements was compared with Bland-Altman graphs between the two methods. Results Before surgery, the intraclass correlation coefficients (ICCs) of the mean corneal endothelial cell density were 0.976, 0.961 and the coefficient of variation (CVs) were 0.086, 0.068 for SP-1P and EM-3000 respectively. The 95%confidence intervals of central endothelial cell density were 148.27-209.87 cells/mm2 between SP-1P and EM-3000. One week after SMILE, the ICCs of the mean corneal endothelial cell density were 0.973, 0.879 and the CVs were 0.076, 0.090 for SP-1P and EM-3000 respectively. The 95%confidence intervals of the central endothelial cell density were 225.86-316.84 cells/mm2 between two specular microscopes. The difference of corneal endothelial cell density before and after surgery was statistically significant between the two specular microscopes (P<0.05). Conclusion The measurement of central corneal endothelial cell density before SMILE with SP-1P and EM-3000 are consistent. And the measurements early postoperatively are different. Key words: Myopia; Specular microscope, non-contact; Density, endothelial cell, cornea; Small incision lenticule extraction