In response to the special requirements of summer high school students’ examinations and military inspections, especially the femtosecond laser surgery that many parents and students are particularly concerned about, we have compiled the following frequently asked questions, which we hope will be helpful to you. Q: What is “femtosecond”? A: “Femtosecond” is a kind of laser that operates in the form of pulse, and the duration is very short, 1 femtosecond is one ten billionth of a second, which is thousands of times shorter than the shortest pulse obtained by using the method of electronics, and it is the shortest pulse that human beings can obtain under the experimental conditions at present. This is the first characteristic of femtosecond laser. The second characteristic is that it has a very high instantaneous power, which can reach one trillion watts, which is a hundred times more than the total power generated in the world at present. The third characteristic is that it can be focused into a region of space smaller than the diameter of a hair, making the strength of the electromagnetic field several times higher than the force of the nucleus of an atom on its surrounding electrons. In the medical field, the femtosecond laser can be used as an ultra-precision surgical knife, which has been successfully applied in the field of ophthalmology. Therefore, myopic laser surgery utilizing femtosecond is more precise and safer. Q: Is femtosecond laser surgery safe? A: Compared with the previous surgical methods, the biggest advantage of femtosecond laser surgery is that it can make corneal flap with very high accuracy, and its accuracy (average fluctuation: 10-15um) is 3 times higher than that of laminar knife (average fluctuation: 30-45um), and the probability of the actual occurrence of corneal flap complication is even tens of thousands of times lower. In addition, the negative pressure of the suction ring used to create a corneal flap with the femtosecond laser (approximately 35 mmHg) is significantly lower than the negative pressure used to create a corneal flap with the mechanical corneal laminator (approximately 65 mmHg). Therefore, femtosecond laser surgery, which can greatly improve the safety of quasi-surgery, is a great boon, especially for patients with thin corneas, large corneal curvature variability, and high myopia. Q: What is the most serious complication that occurs in femtosecond laser surgery? A: Femtosecond laser surgery, because it eliminates the need for a mechanical blade to make a corneal flap, can eliminate almost all serious complications caused by flap making. From the results of nearly 300,000 femtosecond LASIK surgeries performed so far, no serious complications related to the surgery have been found. Q: How long has femtosecond laser surgery been performed? A: Femtosecond laser has been certified by FDA since 2002, and our center spent millions of dollars to introduce femtosecond equipment in 2011. Since the center was established in 1997, more than 60,000 surgeries have been successfully performed. Q: Will there be any glare or double vision after femtosecond laser surgery? A: Femtosecond laser surgery uses laser to make corneal flap without blades, it can make corneal flap with very precise thickness and smoother surface, and it is almost impossible for the flap to shift, free or broken. Therefore, the occurrence of glare and double vision after surgery can be greatly reduced. However, the occurrence of glare and double vision after surgery is not only related to the corneal flap, but also related to the smoothness of the excimer laser corneal cutting surface, the size of the higher order wavefront aberration after surgery, the size of the pupil and other factors. After femtosecond laser surgery, there is also the possibility of glare and double image, because the corneal flap is smoother, so the occurrence of glare and other phenomena after surgery will be less. Q: Is there any pain during femtosecond laser surgery? A: Compared with conventional excimer laser surgery, femtosecond laser surgery is mainly different in the production of corneal flap, and the laser cutting after the flap is completed is the same. The surgery is carried out under surface anesthesia, i.e. only two eye drops are needed during the surgery. There is a transient black haze and swelling sensation when the corneal flap is made, and no obvious pain. Q: Why is femtosecond laser surgery so expensive? A: The cost of femtosecond laser surgery is$12,800 -$14,800 (for both eyes), which is indeed quite expensive compared to the conventional excimer laser surgery of$4,800 -$8,800 (for both eyes). This is due to technological advances, the realization of the entire “knife-free” surgery, the cost of the instruments and equipment required. Whether in terms of the accuracy and smoothness of the corneal flap, or the patient’s postoperative satisfaction, femtosecond laser surgery is worth every penny.