Surface Metrology and 3-Dimensional Confocal Profiling of Femtosecond Laser and Mechanically Dissected Ultrathin Endothelial Lamellae

Abstract

PURPOSE. To determine the feasibility of confocal profiling in measuring surface roughness and obtaining 3-dimensional reconstructions of mechanically dissected and femtosecond (fs)-laser photodisrupted endothelial lamellae. To determine the predictability of single-pass dissection of ultrathin endothelial lamellae using a novel motor-driven linear microkeratome. METHODS. Thirty (n ¼ 30) human corneas were harvested using a motor-driven linear microkeratome (n ¼ 20); a hand-driven rotatory microkeratome (n ¼ 6); and a 60-kHz fs laser (n ¼ 4). Surface roughness was measured using an optical profiler operated in confocal microscopy mode followed by environmental scanning-electron-microscopy. RESULTS. Mean surface roughness for the fs laser, motor-driven linear microkeratome, and hand-driven rotatory microkeratome measured 1.90 6 0.48 lm, 1.06 6 0.42 lm, and 0.93 6 0.25 lm, respectively. Femtosecond photodisrupted lamellae were significantly rougher than mechanically dissected lamellae (P < 0.001). Mean (6SD) cutting depth with the motordriven linear microkeratome measured: 552 6 11 lm (550-lm head); 505 6 19 lm (550-lm head); 459 6 19 lm (450-lm head); and 392 6 20 lm (400-lm head). CONCLUSIONS. Confocal microscopy allows quantitative surface roughness analysis and 3-dimensional reconstruction of human corneal lamellae. Femtosecond-laser photodisruption at 60 kHz results in rougher surfaces compared with mechanical dissection. The motor-driven linear microkeratome allows single-pass dissection of ultrathin endothelial lamellae with a standard deviation 20 lm