Laser eye surgery

PRK - Photoreactive keratectomy is a laser procedure used to correct low and moderate myopia (short-sightedness) and astigmatism using an excimer laser.

• During this operation the epithelial layer of the cornea is first mechanically removed (the epithelium itself regenerates within a few days after the operation).
• Subsequently, part of the cornea is removed so that the light entering the eye is focused exactly on the retina and the image we are watching is sharp.
• To protect the eye a contact lens is inserted at the end of the operation (it is worn until the corneal epithelium heals).

It is a type of an eye surgery in which a laser was used for the first time and was performed in 1987. It is especially suitable for patients with a very thin cornea.

The disadvantages of the operation are some pain, watery eyes and sensitivity to light (photophobia) with a recovery time of about 5 days.

With this procedure the risk of developing dry eye syndrome (an eye that has few tears and needs drops regularly) remains and the improvement of vision is only after a few weeks.

Because of these disadvantages and risks, more modern methods of laser treatment - LASEK and LASIK - have been introduced.

LASIK (Laser in-situ keratomileusis) is a laser surgery for the correction of myopia (short-sightedness), hyperopia (long-sightedness) and astigmatism (dioptric disorders). Both types of lasers are used in this operation.

• During this operation the corneal lamella is first folded back (using a femtosecond laser - a thin part of the cornea is cut and folded back).
• The deeper layers of the cornea are then adjusted as needed (flattened in nearsighted patients or curved in farsighted patients). An excimer laser is used, which performs the so-called photoablation of the stromal bed.
• At the end of the operation, the lamella is returned to the eye. It will heal on its own within 12 hours.

The advantage of the operation is the return of sight after a few hours after the operation.

Several modifications of LASIK operations are available, such as: iLASIK, FemtoLASIK, Z-LASIK, EpiLASIK.

This method is not suitable for patients with too thin corneas and severe hypermyopia (long-sightedness).

LASEK (laser assisted epithelial keratomileusis) is a laser eye surgery suitable for myopia (short-sightedness), hypermetropia (farsightedness) and astigmatism, combining the advantages of PRK and LASIK. It is more tissue-sparing and therefore also suitable for patients with thinner corneas.

• The corneal epithelium is not cut but separated by the action of alcohol.
• It continues with treatment of the cornea (laser photoablation) with an excimer laser.
• At the end of the operation the corneal epithelium is returned to its original place and the eye is covered with a protective-lens that is worn for a few days (3 - 4 days until the epithelium heals).

SMILE or RELEX SMILE is a method in which the cornea is treated with a femtosecond laser and this cut part of the cornea is removed by using a small arc-shaped incision, which has the shape of a smile    ͜   (hence SMILE).

The advantage is that this operation does not create a lamella of cornea as in other surgeries and is therefore applicable to patients with thinner corneas. The procedure is almost painless. The disadvantage is the higher price of the procedure.

It is suitable for patients with myopia and astigmatism.

Corrective laser operations are intended to correct dioptric errors (myopia, hypermetropia and astigmatism) in eyes that do not suffer from any other eye disease (for example: cataracts, glaucoma).

Before the surgery an examination of the patient is necessary:

• The eyesight (visus, vision) is examined to determine the dioptric error of the eye. The anterior segment of the eye is also examined - eyelids, tear film, cornea, iris and lens, conjunctiva.
• Then the retina and optic nerve are examined. It is important to measure the intraocular pressure.
• Corneal topography - the device makes a 3D map of the refractive error of the cornea.

The eye must be dialted during the examination (mydriasis) - the vision will be therefore worsen for about 4 hours (you can see only dimly) and after the examination it is necessary to arrange taking you home. It is not possible to operate on dilated eyes with a laser, so you will need a new appointment for the laser operation.

The examination as such takes around 1.5 - 2 hours. Your ophthalmologist will inform you about all kinds of examinations.

If an operation is planned, it is necessary not to wear contact lenses for at least 5 days before the procedure and replace them with glasses so that the cornea is not irritated.

• On the day of the operation, the surface of the eye is numbed using anesthetic drops.
• Protection of the eye during surgery against involuntary movements is performed using an automatic system (eye-tracker) and the laser therefore turns itself off.
• The procedure takes about 5 - 15 minutes per eye.

After laser operations the patient can see immediately, but the image may be blurred. Vision is usually corrected within 7 days and the results with correction are visible within 1 month.

The sauna, swimming pool and heavier physical activity can be performed after one month from the operation.

After the procedure, the patient may experience pain (burning and cutting of the eyes), sensitivity to light, dryness of the eyes or - on the contrary - tearing, redness of the eye. These symptoms tend to go away on their own within a few days.

The operation is performed on patients after the age of 18 (ideally 18 - 45 years).

The dioptric error of the eye must be stable (diopters have not changed for at least 1 year), without diseases of the retina and cornea (e.g. corneal scars).

The operation is not suitable for patients with severe diabetes, immune diseases, rheumatic diseases, pacemakers.

The procedure must be postponed in a case of acute eye infections, during pregnancy and breastfeeding.

Sight is the most important sensory organ of a person and therefore it is necessary to learn about the possible risks of laser operations before the operation.

The most common complications are:

• Dry eyes - laser operation causes a temporary decrease in tear production.
• Increased light sensitivity, pain, redness of the eye.
• Infection.
• Superficial scarring or excessive thinning of the cornea.
• Regression - the problems with sight appear again.
• Blurred vision - for a few days after surgery.
• Vision loss or vision decrease are very rare complications.

Inform yourself about the risks in advance with your eye doctor - ophthalmologist.