Ultrastructure of the lamellar corneal wound after laser in situ keratomileusis in human eye.

A 30-year-old patient with keratoconus, a stable refraction, and normal central corneal thickness had laser in situ keratomileusis (LASIK). Six months later, she had uneventful penetrating keratoplasty for keratectasia. The lamellar LASIK interface could not be clearly identified by light microscopy. The corneal wound site did not stain for methyl metalloproteinase 1 or 2. Both the corneal flap undersurface and the stromal bed were devoid of interconnections and cells. Throughout the lamellar incision, including the laser-ablated zone, the surface was smooth on scanning electron microscopy. The collagen fibrils on both sides of the incision remained well aligned with one another, indicating good flap apposition. Under higher magnification transmission electron microscopy, some collagen fragments were found in the interface, especially adjacent to the hinge. The diameter of the collagen fibrils along the lamellar wound were identical to those farther from the incision. The absence of bridging collagen fibrils and cells between the flap undersurface and the stromal bed confirms the clinically known lack of wound repair at the interface and explains the easy separation of the flap from the stromal bed months after LASIK and the possible formation of an interface fluid pocket.