Abstract
Purpose: :
To evaluate the changes of endothelial cell density and central corneal thickness following Lasik refractive surgery for myopic correction.
Methods: :
A retrospective review of patient records from refractive procedures performed over a three year period (2004-2007) in a single center was performed to identify uncomplicated cases of Lasik myopic correction with adequate data and minimum follow up of 10 months. Measurements of central corneal thickness (CCT in microns), endothelial cell density (CD in cells per square mm), polymegethism as co-efficiency of cell variation (CV) and pleomorphism as percentage of hexagonality (6A) performed with the Konan specular microscope SP 9000 were evaluated. Data from the eye with the highest refractive error from each patient preoperatively, at 4 and 8 months postoperatively were statistically analyzed to identify a possible effect of the refractive procedure.
Results: :
We identified 96 eligible patients (44 male, 52 female) with mean age 29 years.There was a significant mean decrease in CD (123,47 cells/sq mm, P=0.001) and CCT (37,32 microns, P<0.001) values postoperatively. There were no significant differences in the decrease of CD and CCT for correction bellow or above 6 diopters (P=0,72 and P=0,77 respectively) and on the 2 follow up measurements (P=0,57 and P=0,65 respectively).Polymegethism (CV>40) was found preoperatively in 18/96 (18.8%) and postoperatively in 10/96 (10.4%) cases. Pleomorphism (6A<50%) was found preoperatively in 20/96 (20.8%) and postoperatively in 29/96 (30.4%) cases.There were no significant changes in CV (P=0.152) and 6A (P=0.152). CD was negatively associated with pachymetry and CV, lower values of CD correlated with higher values in pachymetry and CV (P<0.001 and P=0.032, respectively).
Conclusions: :
This retrospective analysis suggests that myopic Lasik refractive surgery produces a significant decrease in endothelial cell count and pachymetry, the later being less than anticipated by stroma ablation. These changes do not result in significant polymegethism, are not strongly influenced by the refractive error and do not progress significantly after the 4th postoperative month. Our findings may pose a need for routine preoperative endotheliometry in cases of refractive surgery.
Keywords: cornea: endothelium • refractive surgery: LASIK • refractive surgery: complications