Lasik

Information about LASIK

What is LASIK?

Laser in-situ keratomileusis (LASIK) is a laser surgical procedure for correcting vision problems. The principle of all laser eye procedures is to change the curvature of the cornea in order to increase or decrease the refractive power of the eye and thus compensate for the respective visual impairment.

In LASIK, the surgeon first partially separates a thin layer from the cornea using a highly developed micro-scalpel, the microkeratome, and folds it over. In order to change the refractive power of the eye, in a second step, corneal tissue is removed from the exposed inner corneal layer using the excimer laser.

To correct nearsightedness, the tissue is flattened in the middle. This reduces the curvature of the cornea. In the case of farsightedness, the cornea is removed in a ring around the middle, thus achieving a stronger corneal curvature. The surgeon then places the folded corneal layer back on top. Femto-LASIK is a newer form of LASIK. The microkeratome is replaced by the femtosecond laser.

Who is the procedure suitable for?

LASIK can be used to correct short-sightedness, long-sightedness or astigmatism. However, the operation is not suitable for every patient. For the operation, the cornea must be sufficiently thick overall, but also under the incision. The greater the refractive error, the more tissue must be removed to correct the refractive error. Once the refractive error reaches a certain degree, the operation is no longer possible.

The Refractive Surgery Commission of the German Ophthalmological Society and the Professional Association of Ophthalmologists in Germany has issued the following recommendations for the use of LASIK:

LASIK can be used for short-sightedness up to -8 diopters, for astigmatism up to 5 diopters and for long-sightedness up to +3 diopters. An operation is also possible if the patient is also suffering from presbyopia. One eye is then adjusted to distance vision. The other eye is corrected so that near vision is optimal.

LASIK can be used to a limited extent for short-sightedness up to -10 diopters, for astigmatism up to 6 diopters and for long-sightedness up to +4 diopters. The Refractive Surgery Commission defines this limit range: the procedure can be used, but the results are increasingly poor and the side effects more frequent; comprehensive patient information is necessary.

The operation must not be performed in cases of chronic, progressive corneal diseases, cataracts, glaucoma with severe restriction of the field of vision, exudative macular degeneration and a form of corneal protrusion (keratoconus forme fruste).

How does LASIK surgery work?

Before the operation, the patient may be given a mild sedative. The eye is numbed with eye drops containing a local anesthetic and held open with an eyelid speculum. The surgeon uses a microkeratome to cut a 0.1 to 0.15 millimeter flat layer from the cornea. In one place, the corneal layer remains connected to the rest of the cornea. The piece of cornea (flap) is folded to the side.

The excimer laser is then used. The patient's values were entered into the device before the procedure. The laser is set so that the corneal tissue is removed according to the values. After the laser has removed the tissue, the surgeon folds the flap back. The corneal layer grows back on its own. The entire procedure usually takes less than 10 minutes per eye.

What is the healing process like after the operation?
In the first few hours after the operation, the eye may burn and the patient's vision may be blurred. However, the next day, vision is already significantly better.

In the first few weeks, vision may deteriorate slightly again as the pit in the cornea partially fills up with corneal epithelium. After about six weeks, vision is usually restored. It may be necessary to undergo another operation if vision has changed too much.

What are the risks?

Patients often suffer from increased dryness of the eyes temporarily. Vision at dusk may also be impaired: patients see halos around light sources and shadows.

Mistakes are very rare when cutting the cornea. Also very rare are detachment of the top layer (epithelium) of the cornea, wrinkling of the anterior corneal lamella during wound healing, weakening and bulging of the cornea, inflammation or infection with severe scarring.

Complications are more likely if major corrections are necessary. Complications occur more frequently with farsightedness than with nearsightedness. LASIK is therefore only recommended for farsightedness up to +3 diopters.
What alternative laser surgical procedures are there?

As an alternative to LASIK, surface treatments (PRK, trans-PRK, LASEK, EPI-LASIK) or refractive lenticule extraction (REFLEX) are possible.

In surface treatments, the doctor uses the excimer laser to remove the surface of the cornea to correct the visual impairment. While the epithelium is removed in PRK, trans-PRK or LASEK, in EPI-LASIK, which is the most commonly used procedure today, the surgeon simply pushes the epithelium aside and then places it back over the defect. To protect the cornea, a contact lens is inserted for a few days, under which the superficial wound heals in a few days. Surface treatments are the cheapest laser surgical procedures. The disadvantage, however, is that vision is usually limited in the first week after the operation. There may also be slight pain.

During refractive lenticule extraction (RELEX), a tissue disc is removed from the inside of the cornea using the femtosecond laser to correct the refractive error. The surgical method is recommended for myopia up to -8 diopters, limited to -10 diopters, and for astigmatism up to 5 diopters. With RELEX FLEX, a tissue disc is created using a double cut with the femtosecond laser. The doctor lifts the upper corneal lamella, removes the tissue disc and folds the lamella back again. It grows back on its own. With RELEX SMILE, the tissue disc is removed through two side openings.
Which doctors and clinics are LASIK specialists?
Surgical correction of vision problems is best done in an eye clinic that specializes in laser eye surgery. Modern refractive surgery procedures now have a high level of quality. The specialized ophthalmologist examines the eye thoroughly, explains the patient and recommends a suitable method depending on the degree of vision problems. Bonn University Hospital is one of the best hospitals in Germany.