RELEASE OF CALCITONIN-GENE-RELATED PEPTIDE IN TEARS AFTER EXCIMER-LASER PHOTOREFRACTIVE KERATECTOMY

BACKGROUND: Sensory nerves known to affect corneal healing are damaged to a variable degree after photorefractive keratectomy (PRK). To sear ch for nerve-bound factors involved in corneal healing, we monitored t ear fluid calcitonin gene-related peptide (CGRP) levels of six human e yes undergoing PRK. METHODS: CGRP concentrations were determined using an immunoassay. RESULTS: Normal human tear fluid contains CGRP. The m ean CGRP concentration was slightly increased postoperatively, despite a marked tear fluid hypersecretion. Consequently, an almost tenfold i ncrease in release of CGRP in tears was observed on days 1 and 2 after PRK. Values measured on day 7 had returned to a normal level. CONCLUS ION: The observed postoperative increase in release of CGRP in tears m ay have an impact on the healing of PRK wounds. Extensive neural damag e following deep photoablations may impair healing and should probably be avoided.