NORMAL HUMAN CORNEAL CELL-POPULATIONS EVALUATED BY IN-VIVO SCANNING SLIT CONFOCAL MICROSCOPY

Purpose. To analyze cellular populations in healthy human corneas. Met hods. The study group consisted of 58 eyes of 45 patients with normal corneas. The age distribution was 45 +/- 17 years (mean +/- SD; range, 20-84). Scanning slit confocal microscopy of the central corneas was performed. The images were analyzed visually for cell morphology, and the densities and areas of cells were measured. Results, No statistica lly significant differences were measured in cell densities or cell ar eas of any corneal layer between female and male patients (p = 0.22-0. 50) nor between right and left eyes (p = 0.16-0.45). The area of super ficial epithelial cells was 913 +/- 326 mu m(2) (mean +/- SD; range, 5 18-2,112), and the superficial epithelial cell density was 1,213 +/- 3 70 cells/mm(2) (mean +/- SD; range, 473-1,929). The area of basal epit helial cells was 177 +/- 19 mu m(2) (mean +/- SD; range, 138-242), and the basal epithelial cell density was 5,699 +/- 604 cells/mm(2) (mean +/- SD; range, 4,1357 +/- 7,267). The average apparent keratocyte den sity was 1,058 +/- 217 cells/mm(2) (mean +/- SD; range, 604-1,599) in the anterior stroma, and 771 +/- 135 cells/mm2 (mean +/- SD; range, 49 3-1,145) in the posterior stroma. The difference in apparent keratocyt e densities between the anterior and posterior stroma was statisticall y significant (p < 0.001). The average endothelial cell area was 334 /- 51 mu m(2) (range, 273-553), and the cell density was 3,055 +/- 386 cells/mm(2) (mean +/- SD; range, 1,809-3,668). The endothelial cell d ensity had a negative, statistically significant correlation with age (r = -0.68, p < 0.001). The densities of the other corneal cell layers did not have a statistically significant correlation with age. Conclu sion. In vivo scanning slit confocal microscopy is a useful tool for s tudying corneal cell populations. Central corneal cell densities were found to decrease significantly with age only in the endothelium. For the first time in human corneas using in vivo confocal microscopy, thi s study statistically confirms a higher apparent number of keratocytes in the anterior stroma than in the posterior stroma.