Let's talk today about what a femtosecond laser is. What are the basic principles of his work and how does he help correct vision?
Theory of Bohr
When at the beginning of the nineteenth century, science reached such a level that it was able to look into the structure of the atom, a new direction arose - quantum physics. The first task was to determine how and why small electrons do not fall on the heavy nucleus of an atom. The previous theory, based on Maxwell's equations, argued that any moving charge emits a field, therefore, loses momentum. Thus, an electron that moves in an orbit around a nucleus must continuously radiate and ultimately fall onto the nucleus. Bohr suggested that electrons can be in an atom only at certain distances from the center, and the transition from one level to another is accompanied by either emission or absorption of energy. This theory was subsequently explained in the framework of quantum physics. The presence of stationary electronic levels opened the way for such an invention as a laser (including a femtosecond).
The theoretical basis of the laser
As soon as scientists understood the structure of the atom, they wanted to learn how to control the state of the electron. Under ordinary conditions, an electron, which for some reason is at a high level of the atom, tends to fill the lower levels if they are free. During the transition, energy is emitted in the form of a quantum of light or a photon. But the transition between any two levels gives rise to different quanta of light. But if many electrons pass simultaneously from a higher level to a lower one, then a flux of many identical photons will appear. The applications of this stream are endless. For example, a femtosecond laser removes a cataract. A level with the so-called inverse population was found in the yttrium-doped ruby: when the electrons are more likely to gather at a high level, and then all together go to a lower level. The main components of the laser are as follows:
- working fluid (a substance in which there is a level with inverse population);
- pumping (a source that “induces” electrons to accumulate at an inverse level);
- a resonator in the form of two parallel mirrors (they concentrate only those photons that are generated in one direction, and all the others are scattered).
The resulting pulse can be continuous or discrete. A femtosecond laser, for example, is of the second type.
Micro, Nano, Femto
All of these consoles represent part of the whole. Milli is one thousandth of something, such as a meter. That is, a millimeter is 10 -3 meters. The prefix femto- means that something weighs or stretches 10 -15 times less than a certain unit. Accordingly, a femtosecond laser has a very short pulse. And in every second fits 10 15 pieces of pulses. Why is such an unimaginably small quantity needed? The fact is that the laser power depends on how long the electrons accumulate at the inverse level. With continuous generation, the laser power cannot be high. But the shorter each pulse, the higher the output. Many processes take much longer, and for the final goal, such a short impulse is not noticeable. The host system seems to be a continuous laser. In this case, the coherence and power of the output beam is much higher.
Cataract
Cataracts are a clouding of the lens. A person who develops such a visual impairment may not know about it: with the development of cataracts on the edge of the pupil, vision is not impaired. But if clouding occurs in the center of the lens, then we can’t not notice the loss of vision. The main causes of this change in the eye are four:
- harmful radiation in large doses;
- head or eye injury;
- diabetes;
- severe stress.
The physical reason is the same - the protein contained in the lens of the eye begins to degrade, collapse. This process is called protein denaturation. In the case of the lens, destruction is irreversible. Previously, white-eyed old people were completely dependent on their relatives, since they were actually blind. However, now this disease is being successfully treated.
Treatment of cataracts with surgery
Traditionally, treatment refers to such interference in the human body that does not violate its integrity: a sore throat is treated with pills and hot tea, a cut finger with ointments and a bandage.
But in this case, the treatment is radical - an operation. Usually this word means wounds, stitches that take a long time to heal, pain and loss of a normal lifestyle. In the case of cataracts, surgery is not necessary, because the incision is usually very small, 2-3 mm, no blood vessels are cut, local anesthesia.
Stages of the operation:
- The eyeball is anesthetized with special drops.
- The iris of the eye is incised (incision no more than 3 mm long).
- A special device is inserted into the lens.
- The device turns the old lens into an emulsion.
- The emulsion is sucked off.
- A new artificial soft lens is introduced.
- The device is removed from the eye.
The procedure lasts no more than 15 minutes, after which a person can already go home himself.
It is at the stage of transformation of the old lens into an emulsion that a femtosecond laser is used. Ophthalmology also knows another example of the use of lasers - correction of myopia and astigmatism. But this is a completely different story.
Laser benefits for cataracts
Immediately we call one significant drawback - this method is quite expensive. However, in all other respects, it is better than previous methods. According to the reviews, the tissue surrounding the lens is less damaged, the conversion to emulsion is faster, the size of the resulting particles is smaller if a femtosecond laser is used in the operation. Reviews about this operation are extremely positive both from patients and from doctors.
We have already mentioned that with the help of lasers, myopia is also corrected. However, until recently, different equipment was used for this operation and treatment of cataracts. The main thing for the patient is the quality of the operation, but the clinic that provides such services would like to spend not so much money on devices. In this case, the Victus femtosecond laser will help out: it can be used to do three different operations. In this case, you just need to change the settings.