Femtosecond laser is a pulsed laser with a very short duration (1 femtosecond = 10-15 seconds), the shortest pulse available to man under experimental conditions. It can be focused to an area of space smaller than the diameter of a hair and is used for microfabrication. Cutting with a femtosecond laser has almost no heat transfer. Used for refractive surgery, it can reduce tissue damage and leave no surgical sequelae. 1. How does the femtosecond laser work for corneal surgery? The femtosecond laser works on the principle of photodetonation. The laser pulses are focused into the corneal tissue, producing a photodetonation effect. Each pulse of light blast produces one micro-ion; for each micro-ion, about 1 micron of corneal tissue is evaporated; the evaporated corneal tissue produces extended blisters and CO2 bubbles, which are absorbed by the corneal tissue and the corneal tissue is thus separated. Femtosecond laser pulses can be stacked and focused at any angle and in any range in the corneal tissue, creating tissue separation at different angles and ranges, so the femtosecond laser can be used for lamellar cutting of the cornea during corneal transplantation and LASIK surgery to create fine implants and flaps. 2. What are the main advantages of femtosecond laser compared to corneal lamellar knife? The main advantages of the femtosecond laser are: (1) significantly reduced surgical risk; (2) embedded flap for more accurate repositioning; (3) avoidance of medical infection; (4) better post-operative visual quality; (5) 100 times greater accuracy; (6) wider range of correction. 3.For which refractive patients is the femtosecond laser suitable? All patients who are suitable for LASIK surgery can receive this surgery, there are five types of people who cannot do traditional LASIK surgery can choose femtosecond all-laser surgery, its scope has been expanded, mainly the following: (1) the previous thin cornea, high myopia and can not do LASIK surgery, 10% of patients can do femtosecond laser flap LASIK surgery. (2) Femtosecond laser can also be done in people who previously could not have a flap made with a mechanical metal knife because of small eye fissures, small corneal diameters, and flat corneas. (3) Femtosecond laser is also the first choice for augmentation surgery after undercorrection or overcorrection after regular LASIK. (4) It is the most suitable procedure for patients who are afraid of cutting the cornea with a traditional mechanical corneal lamellar knife. (5) For those who require high surgical results, femtosecond laser is also recommended.