The hydroblade keratome: Basic principles and microscopic analysis

Purpose. We introduce the operating principles and microscopic tissue effects of new keratome utilizing a small diameter, high speed water jet. Methods. The hand held device is empowered by a CO₂ cartridge which drives a piston to increase the fluid pressure around a sterile water container. The high pressure water is projected from an orifice at a constant speed across a suction template. When the fluid pressure is 1360 atm, beam diameter is 30 μm, and a parallel template without compression is used, the water jet can "cleave" a corneal lamellar flap without adjacent tissue loss or damage. When the fluid pressure is only 200 atm, beam diameter 100 um and a parallel template with compression is used, the water jet can "erode" corneal epithelium from Bowman's layer for rapid epithelial removal. The effect of both cleavage and erosion was tested on freshly enucleated cadaver eyes. Results. There was no hydration, heating or blade-like mechanical effect during both cleaving and erosion. SEM demonstrates lamellar dissections with preservation of interface keratocytes and Bowman's layer with no microirregularities. The detailed preservation is due to the lower relative sectility and differential threshold of these structures to the beam parameters. Conclusion. The hydroblade keratome can operate under both cleaving and erosion mechanisms of tissue separation, and be effectively used for both lamellar flap dissection and rapid epithelial removal with preservation of adjacent structures.