Two Kinds of Laser Femtosecond Myopia Surgery: Full Femtosecond and Half Femtosecond
Femtosecond is a measure of the duration of a standard, and a femtosecond is only a quarter of a trillionth of a second. Even the light in a vacuum of 300,000 kilometers per second can only travel 300 nanometers within a femtosecond time. Laser femtosecond technology is widely used in chemical engineering, physics, biomedicine, etc. It is a hot spot in the field of scientific research.
The "luxurious" femtosecond technology is difficult to directly relate to the daily life of the general public. To say that it is most likely to come into contact with the femtosecond technology, it is necessary to apply the laser femtosecond technology to vision correction. Laser femtosecond technology "grinds" the curvature of the cornea, and then adjusts the refractive power of the cornea to achieve vision correction.
Laser femtosecond technology can accurately open the molecular chain of the eye tissue and create a more uniform and smooth corneal flap. Compared with mechanical corneal lamellar knife, femtosecond laser is used to make corneal flap in LASIK myopia surgery. Its biggest advantage is that it can produce very precise corneal flap thickness with its accuracy (average fluctuation in: 10 to 15 μm) is 3 times the accuracy of lamellar knife (average fluctuation of 30 to 45 μm), but the probability of corneal flap complications is actually tens of thousands of times lower. The laser femtosecond corneal refractive surgery does not destroy the tear circulation, which greatly reduces the incidence of postoperative dry eye.
At present, there are two types of laser surgery in the market: "full femtosecond" laser correction and "half femtosecond" laser correction.
Traditional full-laser femtosecond technology is also commonly referred to as "half femtosecond." Earlier LASIK myopic surgery used a mechanical knife to make corneal flaps, while “half femtoseconds” used lasers to replace mechanical scalpels and achieved great improvement in accuracy. The effect of femtosecond laser LASIK myopia surgery is far better than that of ordinary LASIK myopia surgery, and the recovery period after surgery is greatly reduced. "Half femtosecond" has been verified by accumulating cases in the past decade. It is a relatively stable and mature laser surgery.
Compared to "half femtoseconds", "full femtosecond" technology is currently the most novel technology. Only one laser femtosecond device is needed for the entire operation, which is more simplified in operation, the incision is smaller, and the flap does not need to be cut. However, compared with the traditional "half femtosecond", the disadvantages of full femtosecond are also very obvious. The range of full-femtosecond light zones is narrow, with a regular range of 6.0mm and a maximum light zone of only 6.5mm. It is for this reason that the range of full femtosecond treatment is greatly constrained and can generally only be used to treat 800-1000 degrees of myopia. In order to achieve "valve-free", full femtoseconds require two layers of laser light on the cornea, which results in more corneal loss.
The application of laser femtosecond technology in vision correction is a direct manifestation of technological progress for the benefit of the general public. With the innovation of technology and application of laser femtoseconds, our lives will surely be changed more.