Morphology of Corneal Epithelium in Eyes With Epithelial Slough During LASIK

Abstract

Abstract: : Purpose: To characterize the morphology of epithelium specimens obtained from eyes that have epithelial slough at the time of LASIK. Comparisons were made to epithelium removed during PRK in other normal eyes. Methods: Corneal epithelium was studied using transmission electron microscopy (TEM) and light microscopy with methylene blue staining in four cases of corneal epithelium slough during LASIK (laser in situ keratomileusis), one case of PRK (photorefractive keratectomy) in an eye that from a patient who had an epithelium defect during LASIK in the opposite eye, two cases of PRK in eyes that had clinical signs of epithelial basement membrane dystrophy (EBMD), and in three normal eyes that had PRK. Results: In the eyes with sloughing during LASIK, as well as in the eye that had PRK associated with EBMD and epithelium slough in the contralateral eye, a thick multi-laminated basement membrane was attached to the basal epithelium (figure B). This was not present in the normal controls (figure A). TEM demonstrated hemidesmosomes in the basal cell layer in all specimens, but at decreased density compared with the normal controls. A normal anchoring fibril system was not identified in the cases with slough or EBMD, but it was in the control PRK cases. Conclusion: A thick multi-laminated basement membrane was consistently present in eyes that had epithelial slough during LASIK and eyes with EBMD that had PRK and epithelial slough in the contralateral eye. In these cases, a smaller number of hemidesmossomes were observed and the anchoring fibril system did not appear normal. The break leading to epithelial slough occurred between the epithelial basement membrane and the anterior corneal stroma in each case. Sub-clinical epithelial basement membrane dystrophy is likely associated with epithelial defects during LASIK and may occur even if appropriate technique and instrumentation is utilized.  

Keywords: refractive surgery • cornea: basic science • wound healing