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[The microtrephine: experimental experiences, initial clinical application].

INTRODUCTION
In some diseases of the cornea, histopathological or microbiological evaluation of a stromal samples is essential. On the other hand one of the main aims in the therapy is to keep the cornea clear and without scars. Until now bioptic techniques were not suitable for both aims, getting a sample with minimal damage of the cornea. There was a lack of a method for corneal biopsy which is clinically easily applicable.


MATERIAL
We developed a new instrument for taking corneal biopsies. It is a microtrephine with 160 microns diameter rotating with 30,000 Rpm. It takes biopsies of corneal epithelium and stroma as solid cylinders. The biopsy is non traumatic, safe and repeatable. Biopsies were taken until now on 32 alkali burnt rabbit corneas, 8 enucleated human corneas and 5 patients.


RESULTS
157 biopsies were taken until now. In 75% a sample could be gained. The perforation rate was 0.63% in rabbits. No perforation occurred until now in human corneas. Preparations of light-, scanning- and transmission electron microscopy are presented in this paper for demonstrating examples of application. Microbiological preparations of corneal infiltrates were sterile up to now, representing sterile technique with this new instrument. Herpes simplex PCR was positive in one out of six stromal biopsies from one cornea in supposed herpes keratitis.


CONCLUSION
With the microtrephine samples of the corneal stroma can be taken with high precision. A wide variety of routine diagnostics including repeated measurements on stromal samples of a single cornea are possible now. Early bioptic diagnostics of corneal diseases can be achieved now.