Femtoseconds can also be called femtoseconds, which is a unit of measurement for marking the length of time. Taking 1 second as a reference, 1 femtosecond is only one quadrillionth of a second. It can be seen that femtoseconds represent a very short time. Even if light can fly 300,000 kilometers per second in a vacuum, it can only travel 300 nanometers in 1 femtosecond. At present, laser pointer femtosecond technology, one of the high and new technologies, has been widely used in scientific research, chemical engineering, physics, biomedicine and other fields, opening up a hot spot for scientific research and industry.
Basic principles of laser correction surgery
However, the femtosecond laser technology that sounds so “tall” is really difficult to directly relate to the daily life of the public. The most accessible one is the application of laser femtosecond technology in vision correction. The laser femtosecond technology is used to grind the curvature of the cornea, and then adjust the refractive power of the cornea to achieve the purpose of correcting vision. This is the basic principle of general femtosecond laser vision correction.
At present, there are many myopia correction surgery methods that have been carried out, which can be roughly divided into two categories: one is corneal blue laser pointer surgery, and the other is lens implantation. Among all types of myopia correction surgery, corneal laser surgery is the most frequently used. The frequently mentioned excimer laser (LASIK), half femtosecond, and full femtosecond are actually different stages of corneal laser surgery equipment and technology development. Regardless of the stage, the basic principle is to achieve the goal by cutting the cornea.
Excimer laser treatment of myopia was first used in clinical practice by American doctors in 1985. It has developed rapidly in recent years and was introduced to China in the early 1990s. By using laser engraver femtosecond technology, the molecular chains of eye tissue can be opened precisely to create a more uniform and smooth corneal flap. Compared with the previous mechanical lamellar knives, the femtosecond laser used in LASIK myopia surgery has a very big advantage.
That is to say, it can produce a very precise corneal flap thickness, and its accuracy (average fluctuation: 10～15um) is 3 times that of lamellar knife (average fluctuation: 30～45um), but the actual occurrence of corneal flap complications The probability of the disease is tens of thousands of times lower. In addition, laser femtosecond corneal refractive surgery does not disrupt the tear circulation, which greatly reduces the incidence of postoperative dry eye.