Keratectasia after laser in situ keratomileusis. Clinicopathological case report.

PURPOSE: To describe the morphological features of a prominent ectasia of the cornea after laser in situ keratomileusis (LASIK).

METHODS: The morphology of the ectatic corneas was examined using corneal topography, light microscopy and transmission electron microscopy in 2 cases who underwent penetrating keratoplasty due to poor visual acuity induced by progressive corneal ectasia after LASIK.

RESULTS: On topographic examination, the apex of the corneal surface was observed within the central 3-mm zone, and the smallest thickness was 0.116 and 0.271 mm in each case. On histological examination, the epithelial layer became thinner and detached easily. Bowman's membrane was broken down and folded. An irregular arrangement of the stromal lamellae with fibroblastic keratocytes was found. The fulled fiber cell, a transformed epithelial cell, was visible in a plane on Bowman's layer in the central region. In contrast, the corneal endothelium was intact, and no abnormality was found in both cases.

CONCLUSION: On morphological examination of 2 cases with corneal ectasia, a forward protrusion of both the anterior and posterior corneal surfaces occurred, and epithelial detachment, Bowman's membrane breakage and folding and irregular lamellae were found. The 2 cases had greatly thinned and protruding corneas, yet there was no abnormality in the corneal endothelium.