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Dermot
McGrath
Dr Colin told a session of the 7th ESCRS Winter Refractive Surgery meeting that his clinical experiences using the trephine had been very positive, allowing him to obtain reproducible epithelial flaps safely and conveniently. In the traditional Lasek technique developed by the Italian doctor Massimo Camellin MD, the epithelium, or outer layer of the cornea, is cut not with the microkeratome cutting tool used in Lasik, but with the finer blade of a trephine.
Despite these advantages of Lasek, there is a risk that the alcohol solution can irritate or kill the peripheral corneal epithelium and the conjunctival epithelium. Dead cells can also slough off and impede the advance of new cells from the limbus. Alcohol-damaged cells have also been known to release apoptotic cytokines, which can lead to haze and regression.
“We have designed and evaluated a trephine that is fixated onto the eye with suction. After 20 to 30 seconds, we can very easily remove the alcohol without any risk of leakage because it is in a closed cylinder. “The trephine has a pre-calibrated blade length to obtain reproducible superficial keratectomies or keratotomies. It has a safety stop, which means we have only the possibility to turn three-quarters of a circle and we cut always 70 microns,” Dr Colin said. The epithelial flap was easily lifted in all cases and the corneal cut was similar in all procedures without the risk of an excessively deep keratectomy, Dr Colin added. Summing up, Dr Colin said that refractive surgery was moving inexorably towards the concept of customised corneal ablation treatments, but there are still many issues to be resolved on how such customised techniques could best be carried out. “The key issue now is focusing on where will we deliver the treatment. Will it be on the surface of the cornea, using Lasek techniques, with or without topical mitomycin to prevent the risk of haze formation, or will we concentrate our efforts inside the stroma?” he asked. Joseph Colin
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