Photodisruption with ultrashort laser pulses for intrastromal refractive surgery

摘要

Focusing of femosecond laser pulses into transparent media, such as corneal tissue, leads to an optical breakdown via nonlinear absorption and cutting effects inside the tissue. Due to these nonlinear absorption processes, nearly all kinds of material can be processed by the laser, even inside the bulk of the material. The corresponding energy threshold for achieving such a cutting effect is lowered for fis pulses by several orders of magnitude as compared with ps or ns pulses. Thus, mechanical and thermal effects on the surrounding tissue can be reduced to a minimum. Based on these small side effects, precision in the mum range at cutting in biological tissue, especially in transparent corneal samples of the eye, can be achieved. Therefore, corneal flaps and lenticules for refractive surgery were created in ex vivo and in vivo eyes. The treated eyes showed the possibility of highly precise dissection and, in the case of living tissue, mild woundhealing reactions comparable to what is known from common laser procedures. Moreover, the use of the fs laser offers new possibilities in the cutting Geometry that can be useful in fields of keratoplasty. [References: 13]