At the end of the leaflet, you will find an animation film about the treatment. With the LASIK method, laser treatment is performed in a deeper layer of the cornea. With high corrections, the flattening of the cornea is not applied to the surface (as with PRK, LASEK), but slightly more in-depth into the tissue.
To this end, a thin layer of corneal tissue (a “flap”) is firstly cut loose with a micro kratom or with a laser (Intralase). The flap is still attached to the cornea on one side.
In LASIK, there is a thicker flap, consisting of the epithelium (the superficial layer) and stroma (middle layer of the cornea). It is in contrast to PRK / LASEK, where only the epithelial layer is removed.
The operation procedure
The following steps are taken:
- The eye is pre-anesthetized with eye drops, after which the eye and the environment are disinfected. The face is partially covered with a sterile cloth.
- You sit on a treatment table with the eye under the laser system. An eyelid spreader is placed between the eyelids to keep the eye open so that you cannot blink.
- The device (keratoma) with the knife and a suction ring is focused on the eyeball. The suction ring temporarily increases the eye pressure, which prevents sight for a moment.
- The keratoma blade then cuts a thin layer of corneal tissue (cheese slicing method), with the end still attached to the cornea. The flap can also be made without cutting with a knife, namely with a femtosecond laser (LASIK-Intralase).
- The flap is put aside, and the laser treatment takes place. The tissue flap remains attached to a hinge, and the underlying tissue (stroma) is treated with an excimer laser.
- Using laser pulses, microscopic amounts of corneal tissue are evaporated according to a pre-calculated pattern. The excimer laser adjusts the shape of the cornea precisely for a few seconds. It gives the cornea the desired curvature, with which the deviation is corrected. The central part of the cornea is flattened.
- A microscopic amount of tissue is evaporated under the flap with new laser pulses. During the laser treatment, you must continue to follow the light, and this keeps the laser well centered. The eye deviation is corrected in steps of 0.25 diopters (as is the case with glasses or contact lens strength).
- In myopia (myopia), the central part of the cornea is flattened, making the cornea flatter. With hyperopia (farsightedness), the edges of the cornea are flattened, making the cornea steeper.
- By using an eye tracker, the laser beam continues to follow the eye exactly, even with the slightest eye movement.
- After the laser treatment, the flap is returned to its original position. The flap sucks directly and reattaches to the cornea without the need for stitches. You can then flash again.
- You will be given antibiotic drops.
- Both eyes can be treated in one day.
The eyesight has already recovered reasonably on the first day after treatment, although it can sometimes take several days to weeks before the cornea is completely clear. Checks take place after 1 week and after that, depending on the wound healing. In the first weeks, a slight irritation (sand grain feeling) is experienced because the wound healing of the superficial layer of the cornea has yet to take place.
The replaced cornea flap takes some time to recover. Therefore, rubbing in the eyes is not allowed during the recovery process, and you will receive goggles for the first nights.
With LASIK, lower and medium strengths of myopia (-1.00 to -10.00 diopters), cylindrical deviations (up to 5.00 diopters), and farsightedness (up to +4.00 diopters) can be corrected. More corneal tissue must be removed when the correction of substantial eye defects is necessary. If this were done on the outside of the cornea, such as with PRK, the chance of disturbing scar formation would increase greatly.
For larger eye corrections, the flattening of the cornea is therefore not applied to the surface, but slightly deeper into the cornea tissue, as with the LASIK. It turns out that this treatment reduces the risk of disturbing scars. It must be determined in advance whether the cornea is thick enough to allow sufficient flattening. For example, the cornea must be> 460 µm thick.
The LASIK is no longer suitable if the strengths are too high. Higher strengths can be better treated with artificial lens implantation.
Advantages and disadvantages LASIK
The advantages of the LASIK method compared to the PRK / LASEK method are:
- Less pain after treatment.
- Faster recovery of vision.
- Less chance of scarring (haze).
- LASIK can be applied at slightly higher strengths (-1.00 to -10.00 diopters). Then at PRK (-1.00 to -8.00 diopters).
Disadvantages of the LASIK
- The operation has more of an “operation-like” character.
- Complications when making a corneal flap.
- Flap complications after surgery.
- The cornea must be at least 460 µm thick. Otherwise, LASIK is not possible.
The final results (correction of spectacle power, vision without glasses) of the above techniques are comparable to the PRK / LASEK method. Each method has its advantages and disadvantages. The results depend on the degree of myopia (myopia) or farsightedness (hyperopia). The strength is expressed in D (diopter), the eyesight (vision) as a percentage. Examples:
- for myopia (myopia) down to -6.00 D:, this is the ideal strength for a LASIK laser treatment. Approximately 90% of people achieve an uncorrected vision (without glasses correction) of ≥ 100%. In 90% -100% of the treated eyes, an uncorrected vision of ≥ 50% is achieved. At approximately 90%, the spectacle strength achieved after the laser treatment is ≤ 0.50 D.
- with moderate myopia (myopia) between -6.00 and -10.00 D: the higher myopia, the less the results. About 30% -50% of the treated eyes achieve a vision of ≥100%, about 50-100% of the eyes achieve a vision of ≥ 50% At higher strengths, the results are poor, and laser treatment is not recommended. A Phase Intraocular lens implantation is a more suitable treatment in this category of patients.
- In myopia with astigmatism (cylindrical deviation): in about 50-90% of the treated eyes, and uncorrected vision (without glasses correction) of ≥ 100% is achieved.
- Correction of hyperopia (farsightedness) of <+3.50 D: approximately 30-70% achieves a vision of ≥ 100%. About 40-90% achieve a vision of ≥ 50% (depending on the degree of farsightedness, from 0.50 D to 3.50 D). The results are less good than with myopic eyes and depending on the degree of foresight.
- Correction of hyperopia (from +3.00 to +5.00 D): only 10-20% achieve a vision of ≥ 100%, 45-90% achieve a vision of ≥ 50%. Due to the poor results in patients with higher farsightedness than +3.0 to +3.50 D, laser treatment is therefore not recommended.
About 95% of the patients appear to be satisfied after a primary LASIK treatment ( article: LASIK world literature review 2009 ). The reasons for dissatisfaction include:
- the unrealized result (laser removal of the spectacle strength),
- halos and glare,
- dry eyes, and