Composition of the excimer laser-induced plume produced during LASIK refractive surgery

Abstract

Because of concerns about potential hazards to surgical personnel of the plume associated with laser refractive surgery, this study was performed to characterize the composition of such plumes. Filter elements were removed from the smoke evacuator of a VISX S3 excimer laser (filter pore size ~0.3 microns) and from a Mastel Clean Room ( filter pore size ~0.2 microns) used with a LADARVISION excimer laser. The filters from both laser systems captured the laser-induced plumes from multiple, routine, LASIK patient procedures. Some filters were processed for scanning electron microscopy, while others were extracted with methanol and chloroform for biochemical analysis. Both the VISX "Final Air" filter and the Mastel "Clean Room" filter captured material that was not observed in filters that had clean operating room air only passed through them. In the VISX system, air flows through the filter unit parallel to the filter matrix. SEM analysis showed these filters captured discrete particles of 0.3 to 3.0 microns in size. In the Mastel Clean Room unit, air flows orthogonally through the filter, and the filter matrix was heavily layered with captured debris so that individual particles were not readily distinguished. Amino acid analysis and gel electrophoresis of extracted material revealed proteinaceous molecules as large as 5000 molecular weight. Such large molecules in the laser plume are not predicted by the existing theory of photochemical ablation. The presence of relatively large biomolecules may constitute a risk of allergenic reactions in personnel exposed to the plume, and also calls into question the precise mechanism of excimer laser photochemical ablation.