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Impressum
Histopathologic findings after LASIK
Philipp W., Speicher L., Göttinger W.
University Eye Clinic Innsbruck, Austria
Objective: Histopathologic findings of human corneas after LASIK
have only sporadically been published. In this paper we present histologic,
immunohistochemical, and electronmicroscopic findings of 5 patients who
underwent keratoplasty due to complications after LASIK.
Methods: Corneal buttons were obtained at the time of penetrating
keratoplasty due to iatrogenic keratectasia (3 cases), and due to irregular
astigmatism (2 cases) after LASIK. Immunohistochemistry was performed
on frozen sections using antibodies against collagen types I,II, III,IV,V,VI,
keratan and dermatan sulfate proteoglycan,against cytokines TGFb, PDGF-AA,-
BB,bFGF,HGF and their receptors.
Results: Histopathologic examination of corneas with keratectasia
showed thinning of the central stroma with a residual thickness of 250m,
260m, and 370m, respectively. Only traces of wound healing with minimal
scar tissue were present at the flap margin where dehiscence of Bowman's
layer was visible. Under the flap beyond the wound margin it was mostly
impossible to detect the interface for certain because the adjacent stroma
had a regular and normal appearance. However, 2 corneas showed an artificial
space between the superficial flap and the posterior residual stroma with
only few collagen lamellae being crossing between these structures. One
cornea after hyperopic LASIK showed significant epithelial thickening
in the paracentral ablation zone. Immunohistochemistry only sporadically
revealed minimally increased staining of dermatan sulfate proteoglycan
at the flap margin. Furthermore, increased staining of HGF was typically
found on keratocytes/fibroblasts at the wound margin.
Conclusions: The results of the present study show that the wound
healing response is generally very poor after LASIK which may result in
significant weakening of the tensile strength of the cornea probably due
to a biomechanically almost ineffective superficial lamella.