Danish Medical Bulletin - No. 3. September 2004. Vol. 51 Page 300.

ABSTRACT OF PhD DISSERTATION

Characterization of
corneal wound repair
after laser in situ keratomileusis

Anders Ivarsen

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This PhD dissertation has been accepted by the Faculty of Health Sciences at the University of Aarhus, and defended on May 19, 2004.

Official opponents: Jan Ulrik Prause, Rudolf Guthoff, Germany, and Jesper Hjortdal.

Tutors: Torben Møller-Pedersen and Niels Ehlers.

Correspondence: Holme Parkvej 363, DK-8270 Højbjerg.

Dan Med Bull 2004;51:300.

ABSTRACT

The PhD dissertation consists of five papers and one review, and is based on studies performed at the Department of Ophthalmology, Aarhus University Hospital.

Within the last decade, excimer laser keratorefractive surgery has become a popular alternative to spectacles or contact lenses for the correction of myopia. By removing tissue with an excimer laser (photoablation), the anterior corneal surface can be reshaped, causing predictable changes in the corneal refractive power. In laser in situ keratomileusis (LASIK), the photoablation is performed in the corneal mid-stroma, below a hinged tissue-flap. Post-operative problems include a gradual loss of the refractive effect (regression), and complications related to the LASIK-flap. The corneal wound repair seems to play a role for development of these complications. However, the dynamic changes in the post-LASIK wound repair are largely unknown.

The PhD dissertation characterizes the wound repair in the corneal centre and at the flap margin after LASIK in rabbits using in vivo confocal microscopy and immunofluorescence histology. Evaluated parameters include temporal changes in corneal thickness, reflectivity, and morphology, as well as histological changes in selected structural proteins and growth factors.

In the central cornea, LASIK induced a minimal wound healing response, without TGF- β signalling or myofibroblast transformation. The total corneal rethickening (regression) measured approx. 20% of the total photoablation depth, and was due to stromal regrowth and minor epithelial hyperplasia. Interestingly, the induction of a major anterior keratocyte loss (by epithelial debridement) did not intensify the central corneal wound repair. In contrast to the few morphological changes in the central cornea, fibrosis was detected in a narrow band peripheral to the flap edge. The lateral extension of this peripheral fibrotic wound repair was sharply delimited by the incisional gap in the epithelial basement membrane. In all animals numerous reflecting particles were detected at the LASIK interface and were demonstrated to consist of plastic fragments generated by the microkeratome during surgery.

The present observations of dynamic changes in corneal wound repair after LASIK contribute to the understanding of post-LASIK complications.
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