Operation on the eyes of PRK

Photorefractive keratectomy is the first technology for correcting vision with the help of a laser. The invention and introduction of it was already in the 80s of the last century. Since that time, the original technique has undergone changes and improvements, but in some cases PRK is still the only available method of laser vision correction.

What it is

The cornea is a transparent lens that covers the front of the eye and has mainly a protective function. Its thickness in the center is mm, and at the edges reaches 1 mm.The diameter varies within 1 cm, having a difference in horizontal and vertical dimensions of approximately 6 mm.

The core substance of the cornea (stroma) consists of transparent connective fibers and is bounded on both sides by two membranes. Outside, it is consistently covered with Bowman's membrane and epithelium, from the inside - Descemet's membrane and endothelium.

Since the cornea has the shape of a lens, one of its functions is light refractive, and it is on this property that the essence of laser vision correction is based.By changing the thickness and curvature of the cornea with a laser, surgeons try to change the refractive properties of a natural lens in one direction or another.Thus, a correction is possible:

• Myopia (range from to Dptr);
• Farsightedness (up to +3 D);
• Astigmatism (from to Dptr).

Features of the procedure

Since the stroma is the most voluminous corneal layer, the corrective effect affects it to a greater extent.However, to reach it, it is necessary to overcome two surface layers (epithelium and Bowman's shell), and it is the methods of achieving the inner layer of the cornea that distinguish the original and improved techniques PRK:

• M KFRK.Mechanical removal of surface layers is carried out with a special trowel (chamfer). This method is the very first development for KGF operations, but in some cases is the only acceptable way to effect correction;
• Trans FRK.Removal of the epithelium is performed with the help of a laser, which is a more gentle technique. The latest generation of excimer lasers made it possible to perform the most accurate removal of surface layers having different thicknesses. At the same time, due to software, there is a transition from de-epithelialization to the main refractive step;
• Lasek.The main difference of the method consists in removing the surface layer of the cornea after preliminary special treatment with alcohol and saline solution. As a result, the epithelium binds to the Bowman membrane, and the surface layer is easily removed with a spatula, and at the end of the operation it returns to its place. The main advantage of the technique is a significant reduction in the trauma and timing of adaptation in the postoperative period;
• Epi-Lasik.The difference from the previous technique consists in using a more perfect instrument for separating the epithelium. A special tool called epicardium is called, it allows to separate the epithelial layer along the natural interface of corneal layers. Thus, the risk of complications is reduced: incomplete cut or flap loss;
• Magek.Modification of previous techniques, the main difference of which is the application of Mitomycin C to the stroma of the cornea after the main stage of PRK. The period of drug exposure is 30-60 seconds, after which the operation is completed according to the set program. The main importance of the drug is a reduction in the risk of corneal opacity after surgery. The technique is used, as a rule, for severe myopia.

Each of the techniques has certain merits and demerits, and the final decision on the preferred mode of action is carried out by the refractive surgeon. He can take into account all the nuances of the diagnosis and physiological structure of the eye in each specific case and correlate them with the capabilities of the clinic.

Preparation of the patient

Conducting PRK includes 3 main stages: the preparatory, the actual operation and the period of adaptation.For each of them, the patient should receive as much information as possible from the refractive surgeon to the timing of the exercise, the advantages of the recommended method, and the degree of complications.

The preparatory period includes the following activities:

• Delivery of tests in the order specified by the doctor(necessary blood tests no later than a month before the operation, fluorography - within a year);
• The conclusion of the therapist(and if necessary - narrow-profile specialists) about the state of health. PRK is not performed during periods of acute illness or exacerbation of chronic pathologies;
• If the patient uses contact lenses, they should stop wearing them: hard - 14 days before surgery, soft - for 7 days;
• The operation does not allow the use of cosmetics, as well as the application of a cream or a special mask. The skin should be cleaned to avoid infection;
• During the procedure, the patient is recommended to use loose cotton clothes, which will help to ensure maximum psycho-emotional comfort in the operating room.

If you take any medications or feel an ailment before the operation, be sure to Tell the surgeon that any deviations in health can affect the result of the laser correction.

The phased process of

On the day of the operation, it is forbidden to use any cosmetics or perfumes. It is recommended to take with you a change of shoes, and in clothes to give preference to forms with a fastener in front or an open collar. It is also necessary to have an identity document and sunglasses.

The PRK operation is carried out in the following order:

• An anesthetic of the operated eye is made with the help of drops;
• An eyelash extender is installed on the operated eye, preventing the movement of the eyelids;
• After this, the patient, on the instructions of the doctor, concentrates attention on the luminous point inside the device. If necessary, the eye is fixed with a special vacuum ring;
• The epithelium is removed at the site, which will be adjusted;
• Under the control of the refractive surgeon, the laser forms the cornea with the required parameters;
• After the procedure, the surface of the eye is treated with a disinfectant, anti-inflammatory drugs are instilled and a temporary lens is inserted.

Wearing a temporary lens protects the operated eye from possible external influences, and also reduces possible unpleasant sensations in the postoperative period. If correction is necessary for both eyes, the operations are performed alternately, first on one, and later on on the other.

Postoperative period

The operation lasts on average no longer than 10 minutes, after which the patient within 3-4 days can experience uncomfortable sensations: pain, photophobia, lacrimation, sensation of sand in the eyes.It is in these few days that the main restoration of eye tissues takes place. The strength of discomfort in this case depends on the surgeon's choice of PRK and the individual pain threshold of the patient. At this time, the instillation of anti-inflammatory and analgesic drugs is prescribed.

It is mandatory to be examined by a specialist the next day after the operation and in the future - on the advice of a doctor. If necessary, a sick leave sheet is issued for up to 4 weeks.

The complete process of corneal restoration can take up to 6 months.In this case, the probability of complete recovery of vision is high (up to 80% of cases).In some cases, vision is restored to, which is also a very good result, since it allows you to dispense with everyday life without glasses and contact lenses.

The list of possible complications includes:

• Infectious processes (from which the healthy eyes are not insured);
• Optical effects arising around bright light sources at night (halos, distortions);
• Temporary opacity of the cornea (haze).

To exclude the risk of complications, follow all the recommendations of the doctor, and in the preparation period try To get on consultation to several experts to make a correct opinion about the most suitable for you method.

Recommendations for caring for the patient

The most critical period is the first 3-4 days after surgery, when the epithelium of the cornea is restored and it is most vulnerable to external influences.It is recommended at this time to wear sunglasses, limit the location on the street, and (as directed by the doctor) wearing temporary contact lenses.

It is necessary to exclude or limit situations that cause damage to the epithelium:

• Visiting baths, saunas, swimming pools;
• Being on the beach;
• The use of alcohol, hormonal drugs, vitamin or immunostimulating agents.

Some preventive measures must be followed:

• Evasion from the possibility of infectious diseases, exacerbation of chronic pathologies, pregnancy (as a condition requiring mobilization of all body resources);
• Restriction of physical exertion and overstrain specifically the eye;
• Compliance with a specific diet(the exclusion of spicy and salty foods, fried and smoked, containing carcinogens and supplements).

Restoration of vision is gradual, so do not wait for a miracle right after the operation. At best, at this time, vision can reach preoperative days using glasses or lenses.

Reviews of people

If we compare the methods of FRC and Lasik, then, judging by the reviews, the first method of carrying out the operation is much more painful in the first few days. However, its advantage lies in the fact that it is applicable for practically any thickness and shape of the cornea, While the Lasik technique does not require a too thin shell, because only its temporary removal.And this is not feasible at a thickness below the required parameters.

In the network, there is enough feedback with both positive and negative evaluations of the effectiveness of laser vision correction. To establish the truth, try to get to the reception to experts, and not to merchants.And to ensure the correctness of the recommended method, get the advice of more than one specialist, but several. This will increase the reliability of the diagnosis.

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conclusions

Photorefractive keratectomy is a method of laser correction of vision, which changes the cornea of ​​the eyes. Due to this, positive changes in visual acuity can be achieved with nearsightedness, farsightedness, and astigmatism.

Operation PRK has several undoubted advantages: a high percentage of cure, a "knife-free" surgery technique, a minimal complication, and the possibility of an outpatient postoperative period.

Today, various methods of PRK are among the most advanced technologies and allow you to perform eye correction in a wide range of vision abnormalities in a variety of age categories.

Also read about conservative methods of cataract treatment and what drugs can be taken during this disease.