Refractive surgery is a relatively young area in the treatment of eye diseases. It is based on the principles of refraction of light in such a way as to focus the image directly on the retina. Refraction translates precisely as "refraction." Thus, refractive laser surgery uses the laws of physics from the subsection of optics. The procedure for correcting vision using this method can be applied to almost any person aged 18 to the most advanced years.
Types of myopia and the physics of the correction process
The most common visual defects are myopia and farsightedness. With myopia, a person does not see objects far from himself. With farsightedness, on the contrary, he clearly sees everything that is in the distance, while he is not able to discern what is in front of him, for example, he cannot read. This happens because the lens, which is essentially a lens, focuses the image passing through it, not on the retina, but at the point in front of it - myopia or behind it - hyperopia.
To solve this problem is quite simple - you need to either move the lens to the fundus or move away from it. But to transfer the lens inside the eye is almost impossible, but it is possible, by changing the curvature of the horn frill, press it to the retina or move it away. Almost all vision-correcting operations are based on this principle. They change the bending radius of the front of the cornea.
In this case, the lens shift is made up of microns, but this is enough to restore vision by 100%.
It is clear that other operations are performed in the eyes, for example, a cloudy spot is removed from the cornea or the clouded lens itself changes, but these procedures have no relation to myopia or farsightedness. This is done in order to return vision to a person in principle, since in a severe form of cataracts the eyes see almost nothing.
In which cases the operation is not performed
Refractive surgery affects one of the most delicate and fragile organs of a person, it is clear that there are a number of contraindications for its implementation.
First of all, the procedure cannot be carried out if the patient has any infectious eye diseases, for example, conjunctivitis. Moreover, an operation is performed only if the patient has not suffered from such diseases for 1 year before the procedure. The eye from this point of view should be absolutely healthy.
The operation is not performed if the patient has AIDS or another disease of the immune system. Indeed, after the operation, natural healing should begin, and in the absence or weak immunity this is impossible.
If the patient was forced to take drugs with isotretinoin or amiodarone, the procedure is not performed until all traces of the substances have left the body.
The patient must understand that after the operation, the immune system will be significantly weakened, therefore, all the chronic diseases that he has will certainly manifest themselves. So, often after surgery, the patient shows herpes or a similar disease. It is necessary to bring this information to the patient so that he is ready to undergo appropriate treatment after the operation.
Side effects after surgery
Cataract and refractive surgery are nevertheless penetration into the structure of the human eye. Naturally, after it there are a number of side effects.
After refractive surgery of the cornea, a sensation of the presence of a foreign body arises in the eye. Many patients compare this to the effect of sand in the eyes.
Eyes for several hours or even days are extremely sensitive to light, patients are forced to stay in dark rooms for a long time or go out into the street with dark glasses.
Another side effect is the halo around the light source, many people think that the edges of the window opening or frame are double. After refractive surgery, dry eyes often occur, which leads to physical discomfort.
Surgery complications
Despite the fact that the percentage of complications of refractive surgery is very small, about 1%, but still there may be complications. The patient is notified of this possibility before surgery. Complications include the introduction of an infection into the eye, hyper correction, under correction, irregular astigmatism.
But, as already reported, there are very few such cases and, as a rule, they arise against the background of the fact that the patient himself did not inform the doctors that he had an autoimmune disease or his eyes were infected shortly before the procedure. That is why the condition of the patient before the operation is checked by studying various tests of his blood. Doctors do not often rely on information provided by the patient about themselves.
Laser keratomileusis or LASIK
Modern technologies of cataract and refractive surgery widely use laser equipment. During the procedure, using the LASIK method, a piece of the cornea of the eye is cut out and processed using a femtosecond laser.
Next, the piece returns to its place and is attached using an excimer laser. The flap survives the very next day without visible tissue defects. In this case, the refraction effect occurs and the image is focused on the retina itself, and not in front of or behind it.
This procedure is distinguished by the absence of infection or infectious lesions, pain. Already on the second day, the patient can look at the world with new eyes.
The disadvantages of this method include the following: the cornea of the eye can become so thin that it can no longer withstand intraocular pressure and begins to bend. This, accordingly, will spoil the focus on the fundus, and the person will again see poorly.
This type of operation is used in cases of myopia, hyperopia and astigmatism.
Photorefractive keratectomy surgery - PRK
Refractive eye surgery involves the use of PRK. During the procedure, part of the cells of the cornea is vaporized using a laser, after which a new cornea is formed, but with a different curvature. This procedure takes about 3-4 days, while the patient must wear special lenses that hold the cornea all this time. When it is completely fused and heals, the image is fixed on the fundus, which returns vision to 100% clarity.
This procedure is used on those patients who have a very thin cornea, that is, it is likely that it will stretch under the influence of intraocular pressure. If a sufficiently large area of the cornea is subjected to ablation, then the risk of its partial or complete turbidity increases.
The operation according to the method of intracorneal ring segments - ICKS
The essence of this procedure is the implantation of the artificial part of the cornea of the artificial arcuate strips - intrastromal segments. Previously, similar-shaped strips are cut from the cornea. Implants are able to change the radius of bending of the cornea, which allows you to focus the image at the desired point in the fundus.
This procedure is performed on a patient with not very low vision - from -3 to -1 diopters with myopia. With a change in vision caused by age or other factors, the implants can be changed or removed altogether.
This method is criticized by leading ophthalmologists, since it can cause infection in the eye, there is such an effect as hyper correction or under correction, since it is very difficult to calculate the necessary curvature of the implants.
Installation of phakic intraocular lenses - IOL
Laser correction of the cornea is not equally suitable for all patients. In this case, a special lens is installed directly in front of the lens or behind it. It is implanted under the cornea, so the operation is quite complicated and is not performed in all clinics. At the same time, there remains a high risk of cataracts, glaucoma and other darkening of the lens. Again, there is a high probability of infection in the eye.
Lens extraction
The lens removal operation is performed only at the refractive laser surgery center. Indications for it may be cataracts or hyperopia. During the procedure, the lens is cut out, and an intracorneal lens is installed in its place.
This operation is complicated by the likelihood of retinal detachment or destruction of the posterior lens capsule. That is why it is carried out only in large clinics with modern equipment and professional ophthalmologists. For example, in the center of refractive laser surgery in Yekaterinburg or another large city.
Radial and Astigmatic Keratotomy
This type of operation does not use lasers or other modern techniques. The bending radius of the cornea is changed by making incisions on it with a scalpel. After their healing, the cornea becomes smaller, changes the concentration of the image at the bottom of the eye day. This type of surgery was performed at the dawn of ophthalmology and surgical treatment. Currently, it is used extremely rarely, for a number of contraindications. Also, this type of procedure is prescribed for cataract removal.
Refractive eye surgery is a modern method for solving vision problems. Similar operations are performed for various diseases of the organs of vision. It is important to follow safety measures during the rehabilitation period. You can not abuse alcohol, physically strain. All doctor's prescriptions must be observed, otherwise complications are possible that will require additional treatment. In general, such procedures are always successful, except in some cases, so you should not be afraid.