ABSTRACT
PURPOSE: To compare keratocyte density in corneal stromal layers in keratoconus, post-laser in situ keratomileusis (LASIK) keratectasia, uncomplicated post-LASIK cases, and normal unoperated corneas by confocal scan. METHODS: Thirty-one unscarred corneas from 22 patients with keratoconus, 24 clear corneas from 17 cases with post-LASIK keratectasia, 12 corneas from 7 uncomplicated post-LASIK cases, and 26 corneas from 13 normal unoperated cases were evaluated by using confocal scan. None of the cases were contact lens wearers. Keratocyte densities were determined in 3 stromal layers in each cornea and compared with densities in the corresponding layers of normal unoperated corneas. Cell densities in different corneal layers were also compared in each group. RESULTS: In overall, 93 eyes from 59 patients with mean age of 30 +/- 7.3 years were enrolled. There was no difference in mean keratocyte density at 3 stromal layers between keratoconic and normal unoperated corneas. In post-LASIK keratectasia, keratocyte density in the anterior and posterior stromal layers was significantly lower than that in normal unoperated group. In uncomplicated post-LASIK cases, the keratocyte density at 3 stromal layers was lower than that in normal unoperated group. No difference in keratocyte density was found between post-LASIK keratectasia and uncomplicated post-LASIK cases. Furthermore, in post-LASIK keratectasia, there was a meaningful difference in keratocyte density between the anterior and posterior and between the middle and posterior stromal layers; such a difference was not observed in the uncomplicated post-LASIK cases. CONCLUSIONS: Mean keratocyte density in post-LASIK keratectasia and uncomplicated post-LASIK cases was lower than that in normal unoperated group. Given the different distribution of keratocytes between the stromal layers in the 2 LASIK groups, there was a nonhomogenous distribution of keratocytes in stromal layers in post-LASIK keratectasia. A homogenous distribution of keratocytes in uncomplicated post-LASIK cases may be a factor in prevention of corneal ectasia.
