The free electron laser: a system capable of determining the gold standardin laser vision correction

Introduction. In laser vision correction surgery, lasers are generally util ized based on their beam-tissue interactions and corneal absorption charact eristics. Therefore, the free electron laser, with its ability to provide b road wavelength tunability, is a unique research tool for investigating wav elengths of possible corneal ablation, Methods. Mark III free electron lase r wavelengths between 2.94 and 6.7 mu m were delivered in serial 0.1 mu m i ntervals to corneas of freshly enucleated porcine globes. Collateral damage , ablation depth, and ablation diameter were measured in histologic section s. Results. The least collateral damage (12-13 mu m) was demonstrated at th ree wavelengths: 6.0, 6.1 (amide I), and 6.3 mu m. Minimal collateral damag e (15 mu m) was noted at 2.94 mu m (OH-stretch) and at 6.2 mu m. Slightly g reater collateral damage was noted at 6.45 mu m (amide II), as well as at t he 5.5-5.7 mu m range, but this was still substantially less than the colla teral damage noted at the other wavelengths tested. Conclusions. Our result s suggest that select mid-infrared wavelengths have potential for keratoref ractive surgery and warrant additional study. Further, the free electron la ser's ability to allow parameter adjustment in the farultraviolet spectrum may provide unprecedented insights toward establishing the gold-standard pa rameters for laser vision correction surgery. (C) 1999 Elsevier Science B.V . All rights reserved.