Atomic force microscopic study of the human cornea following excimer laserkeratectomy

The aim cf this study was to examine the corneal surface structures with a new investigative method, the atomic force microscope following 193 nm exci mer laser photoablation. Fresh human corneas were irradiated in vitro with an increasing number of impulses emitted by a 193 nm ArF laboratory excimer laser in order to produce either smooth flat surfaces or stair-like format ions within the cornea. The corneas were investigated in a Topometrix(R) at omic force microscope in their native state. For comparison, three corneas were fixed with glutaraldehyde and processed for scanning electron microsco py. Atomic force microscopy and scanning electron microscopy revealed the same surface characteristics of photoablated corneas, though the preparation for scanning electron microscopy induced considerable shrinkage of the tissues . The layers of the cornea could be distinguished from each other and deepe r ablations of the stroma produced a rougher surface. On the lateral walls of ablated stairs small droplets of ejected material could be seen with sca nning electron microscope. Atomic force microscope produces three-dimensional images of the scanned na tive corneal surfaces and it could be a valuable tool to investigate the co rneal smoothness. Our investigations have provided similar results as those obtained with scanning electron microscopy showing that the laser-ablated corneal surface remains relatively smooth. We suggest that the formation of condense droplets of ejected materials is based on hydrodynamic motions in duced by boiling water solutions. (C) 2000 Academic Press.