What is a femtosecond laser? 1, femtosecond laser is a laser that operates in the form of pulses, the duration is very short, only a few femtoseconds, 1 femtosecond is 10-15 seconds, that is, one trillionth of a second, it is thousands of times shorter than the shortest pulse obtained using electronic methods, effective treatment of myopia, is the shortest pulse available to mankind under experimental conditions. This is the first feature of the femtosecond laser. The first feature of the femtosecond laser is that it is the shortest pulse available to humans under experimental conditions. The third feature of the femtosecond laser is that it can focus to an area of space smaller than the diameter of a hair, making the electromagnetic field several times stronger than the force of the nucleus on its surrounding electrons. It helps us to treat myopia disease. 3. The huge power emitted by the femtosecond laser in an instant is greater than the total power of the world’s electricity generation, which is already in use, and scientists predict that the femtosecond laser will play an important role in generating new energy sources for the next century. The two main principles of femtosecond laser myopia surgery The femtosecond laser is a magical light with a wavelength of 1053nm, and its various advantages have been successfully used in various fields, and eye surgery is no exception. But what exactly is the principle of femtosecond laser to correct myopia? There are two principles of femtosecond laser surgery, one is the light transmission principle and the other is the light blasting principle. First, look at the light transmission principle of femtosecond laser surgery: Before the surgery, the surgeon enters the patient’s basic information data and surgical data into the computer (including the depth of laser focus, which is the distance from the bottom of the cone lens to the laser focus point; the diameter of the corneal flap, the size and width of the tip; the energy of laser cutting, etc.). During surgery, the surgeon operates the femtosecond laser machine and uses the cone lens to hold the cornea in place, thus maintaining the precise distance from the laser head to the laser focus point in the corneal tissue. The depth of laser focus, which is the distance from the bottom of the cone lens to the laser focus point, is where the femtosecond laser machine delivers laser pulses in the pattern set by the surgeon to make various targeted cuts in the cornea. Briefly, what impresses us most about the light transmission principle of the femtosecond laser is the precise directionality and exact positioning of the light transmission. Next, let’s look at the photobursting principle of femtosecond laser surgery: The laser pulses are focused into the corneal tissue to produce photobursting; each pulse of photobursting produces a micro-ion, and each micro-ion, evaporates approximately 1 micron of corneal tissue; the evaporated corneal tissue produces extended blisters and CO2 bubbles, which are absorbed by the corneal tissue and the corneal tissue is thus separated. The computer-controlled optical delivery system generates thousands of laser pulses, which are focused at the same depth in a dense, equal-width, equal-spacing fence-wall grating pattern, producing a light burst that forms a layer of tiny diameter bubbles in the corneal tissue, causing the corneal tissue to separate and form the corresponding separation surface, the cutting surface of the femtosecond laser. This cutting pattern is used to form the horizontal separation surface and the vertical surface. The laser pulses can also be focused at any angle and in any range of stacking in the corneal tissue, forming tissue separations of different angles and ranges. Therefore, the femtosecond laser can be used for lamellar cutting of the cornea in corneal transplantation and lasik surgery to create fine implants and flaps; and for spot sculpting of the cornea in corneal stromal ring implantation surgery to create tunnels. These are the two main principles of femtosecond laser myopia correction surgery, and it is its amazing advantages that make femtosecond laser myopia correction more excellent. The full femtosecond laser is an important breakthrough in the previous refractive surgery, and was made as a trend in refractive surgery at the ESCRS meeting a few years ago. Femtosecond lenticule extraction is a technique in which the laser is precisely positioned in the corneal stroma, and the lens is removed from the corneal stroma to change the refractive power of the cornea. The majority of femtosecond lasers used in LASIK can only create a corneal flap and must be used in combination with an excimer to achieve the treatment goal. The all-femtosecond laser is a laser system that cuts an interface of a specific diameter and curvature at a relatively deep level of the cornea, and then cuts an interface of a specific curvature with a slightly larger diameter at a relatively shallow level of the cornea, with the two interfaces intersecting at the periphery to form a convex lens-shaped corneal lamina in the interlayer. The removal of the created interlayer is equivalent to applying the principle of excimer laser cutting. The newest surgical modality, “flex,” is called femtosecond laser corneal stromal lenticule excision, which is a 10-15 second pulsed laser procedure. Based on the FLEX technique, a more minimally invasive refractive surgery technique has emerged using the femtosecond laser, known as small incision lenticule extraction (SMILE), or commonly known as Smile surgery. Femtosecond laser small incision lenticule extraction is a technique that allows the creation of a corneal flap and the removal of the lenticule using a small incision without the need to create a flap. It can reduce the damage to corneal nerve fibers, reduce the impact on corneal biomechanics, and improve the quality of vision.