The alternative to wearing glasses or contact lenses is gaining popularity
Today, with the help of laser vision correction, performed according to different methods, almost everyone can correct myopia or hyperopia. However, despite the great progress in medicine, laser eye surgery is still associated with high costs and certain risks.
Laser eye surgery techniques
Usually, in eye microsurgery, the so-called excimer (gas) laser is used, which operates on electronic transitions of special molecules that exist only with excess energy compared to the ground state. The first such lasers were distinguished by a significant damaging effect on the cornea. The wide profile of their beam and its heterogeneity caused a sufficiently high heating of the corneal tissue, which entailed burns and corneal opacities. New generation lasers have been modernized. Nowadays, with their help, the refractive power of the eye is changed, which consists in the ability of the latter to “collect in a beam” the incident light rays and is measured in diopters. In people with normal vision, the refractive power of the eye is about 65 diopters. If the figure turns out to be more than the indicated one, it indicates that a person has such a disease as hyperopia; if less, the patient suffers from myopia.
Let’s consider the main methods of laser correction.
LASIK – laser keratomileusis
Today, LASIK laser correction is one of the most commonly used in eye surgery. It is always performed on an outpatient basis. First, the doctor uses a special device – a microkeratome – to create a flap from the surface layers of the corneal tissue with a thickness of 130–150 microns, and then folds it up, giving the laser beam access to the deeper layers of the cornea.
Eye after exposure to a laser beam (surgery to correct visual acuity). The corneal layer is detached and folded back.
Then the laser beam is used directly, acting on the deeper layers. A thin flap is folded back and fixed with collagen – the cornea’s own substance. The chances of successful restoration of good vision will be if the patient’s deviation from the normal refractive power of the eye does not exceed the following values: with myopia -10 diopters, with hyperopia: +4 diopters, with astigmatism up to – 4 diopters.
Photorefractive keratectomy (PRK)
Photorefractive keratectomy is the oldest method of laser vision correction. The first correction using PRK was carried out in Berlin in 1985. Currently, this method is used extremely rarely; as a rule, it is used to treat patients whose refractive power of the eye differs only slightly from normal. The technology of photorefractive keratectomy is a non-contact effect of an excimer laser on the surface layers of the cornea, without affecting the internal structures of the eye. In this case, the newly formed surface of the cornea actually remains open, which leads to severe pain that does not subside for several days, as well as a rather slow healing process.
LASEK – laser epithelial keratomileusis
This new laser vision correction technology is a combination of the aforementioned PRK and LASIK methods. The first LASEK procedure was performed in 1996 by Dimitar Azor (Massachusetts). The operation is performed on the surface layer of the cornea called the epithelium; the thickness of the surface affected by the laser is much thinner (0.05 mm) than with LASIK. However, after surgery, the patient needs to wear contact lenses for several days as a protective “dressing” to prevent injury to delicate, thin tissue. The main advantage of laser epithelial keratomileusis over the LASIK method is that LASEK allows surgery even with a rather thin cornea of the eye.
Phototherapeutic keratectomy (FTC)
This method is used, as a rule, for recurrent destructive processes of the cornea, the presence of superficial scars on the cornea, or progressive corneal degeneration. After local anesthesia, a small part of the cornea (or all of its layers) is removed using heat-generating laser beams and the surface is sanded.
The operation is performed on an outpatient basis. The rehabilitation period involves the constant use of antibiotics, eye drops or ointments. For six months, the patient must have with him the so-called tear fluid substitutes.
Retinal detachment, cracks in it, vascular lesions and some types of tumors can be treated with laser coagulation. The retina, figuratively speaking, is “welded” to its base. A crack or damaged area is burned out with a laser beam, thereby stopping the progression of the disease. Laser-treated sites heal within 1.5-2 weeks from the date of the operation.
During laser vision correction, the patient’s eye is treated with a special syringe.
Laser coagulation is the only and no alternative method for pathological changes in the retinal tissues. After surgery, blood circulation and nutrient flow are usually improved, which can cure many vascular diseases of the eye. Retinal laser treatment is usually performed on an outpatient basis. The patient is instilled with special drops to dilate the pupil and numb the cornea. After they begin to act, the operated person “loses” normal vision for several hours, seeing only vague outlines of objects in front of him. In addition, the eyes become more susceptible to light stimuli, therefore, the patient is not recommended to drive during the day.
Photodynamic therapy (PDT)
With the development of the “wet” form of age-related macular degeneration (AMD), when visual acuity is completely or partially lost in a small area of the retina, photodynamic therapy (PDT) under certain conditions can slow down the development of the disease.
Before the actual treatment begins, the patient is given an injection of Verteporfin, which gradually builds up on the vessel walls. Irradiation with a weak laser beam of a certain color activates Verteporfin that has entered the retina, destroying all neoplasms and affected vessels without harm to neighboring tissues.
After surgery, the patient must take care to protect the eyes from direct sunlight, as new, unwanted activation of Verteporfin can damage the retina.
Laser vision correction cannot be done: people under the age of 18; when changing the refractive power of the eye (“floating” diopters) over the past one or two years; during pregnancy and lactation; with eye diseases such as cataracts, glaucoma or chronic corneal diseases; with immune diseases and diabetes mellitus.
The cost of the procedure
Today, the cost of laser vision correction performed using the LASIK, LASEK and PRK methods in private clinics in Moscow ranges from 40,000 to 120,000 rubles (for an operation on both eyes). This amount, as a rule, includes a specialist consultation, initial and repeated examination, and the operation itself. Separately, the patient will have to pay for additional funds – eye drops, ointments, lenses and bandages.
Risks and complications
Laser vision correction can have serious side effects. Until now, scientists have not been able to make a final verdict regarding the conditions for the occurrence of temporary or permanent diseases after microsurgical intervention. Most often, patients face the following risks and complications:
– Dry eyes;
– Ptosis – drooping of the upper eyelid;
– Inability to distinguish objects well at dusk;
– Increased sensitivity to glare and glare;
– Double eyes, dizziness, big difference between the refractive power of the right and left eyes;
– The need for repeated surgery or vision correction with glasses or contact lenses;
– Clouding of the lens, leading to a decrease in vision (mainly occurs when using the methods LASEK, PRK and FTK);
– The appearance of superficial scars on the cornea;
– “Activation” of the herpes virus;
– Keratectasia – bulging of the cornea of the eye at the site of scar tissue formation, leading to constant fluctuations in visual acuity;
– Infection in the cornea.
Photo from www.dpa.de