In-vivo tissue response to free electron laser

Purpose:We analyzed the effect of energy and rate of cutting on the in vivo ocular response to 2.94 mu m wavelength Free Electron Laser (FEL) incision of the cornea. We were interested in the difference between our clinical observations of the initial laser lesion and the ocular response using the biomicroscope versus optical coherence tomographs. We were also interested in the difference between these clinical in vivo data and our findings from light micrographs of fixed tissue. Methods: Corneas were incised with FEL at 2.94 mu m wavelength and either 2.5 or 3.5 mJ/1.4 mu sec. the rate of movement of the laser beam across tissue ranged from 0.2 mm/sec to 1.2 mm/sec. Eyes were examined for two hours postoperatively using optical coherence tomography (OCT) and compared to the clinical slit lamp examination and to light microscopic examination of fixed tissue sections. Results: OCT revealed a dramatic fibrin response directly correlated to the slow sweep of the FEL beam across the tissue (longer duration of tissue exposure to the laser beam). The OCT was better than examination at: the slit lamp at demonstrating sites of fibrin attachments.