Refractive surgery
What does refractive surgery mean?
Refractive surgery includes surgical procedures that change the refractive power of the eye and correct existing ametropia.
In this surgery, the curvature of the cornea of the eye is changed in one operation in such a way that the image of the object to be seen falls directly on the retina and thus the image of the object arrives in focus on the retina. Microsurgical techniques are used. This means that the operations take place under the microscope using a laser. Due to the rapidly advancing development of laser technology in the last 25 years, these operations are only possible today. Surgery is safe, bloodless, and effective as long as proper procedures are followed.
A prerequisite for a successful operation is that the patient does not have any corneal or other systemic diseases. The patient should be between 21 and 65 years old. The following errors can be corrected with this surgery:
Congenital or acquired astigmatism (astigmatism), e.g. B. after a cataract operation, an accident, etc.
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Myopia
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myopia
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Presbyopia under certain conditions
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Presbyopia under certain conditions
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Myopia associated with astigmatism
The techniques of refractive surgery
Lasik is the most commonly used treatment method in refractive surgery today. In certain cases, however, surface treatment (Lasek / PRK) can also be the better method for the patient to achieve a lasting improvement in vision. The choice of the right method must be decided by the doctor.
The Lasek process
With the surface treatment (Lasek or PRK), the uppermost layer of the cornea (epithelium) is first removed mechanically. Then the center of the cornea is ground down with an excimer laser in such a way that the ametropia is corrected. The superficial wound closes itself within a few days as the epithelium forms again.
This surface treatment is used in the following cases:
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In patients with a thin layer of the cornea
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In patients with dry eyes
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In patients who engage in intense contact sports
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Or even if there is another ophthalmological indication
With surface treatment (PRK / Lasek) long-sightedness, short-sightedness and astigmatism are corrected. The epithelium (the top layer of the cornea) is removed and the ametropia is corrected using an excimer laser. A therapeutic contact lens is then inserted to fix the epithelium and promote the healing process.
The surface treatment is a gentle treatment method and achieves a good quality of vision. Despite a relatively low corneal thickness, a high level of ametropia can be corrected. This method is suitable for people who practice martial arts.
It is the oldest procedure and the side effects are significant. After the operation, the eye will hurt for three to four days and a painkiller will need to be prescribed. Overcorrection is possible for one to two months, which interferes with reading. In addition, a veil may appear in front of the eye, which spontaneously disappears after a few months.
The LASIK procedure
(LASIK is an acronym for Laser In Situ Keratomileusis)
In the LASIK procedure, an approx. 90-160 µm thick lamella of the cornea is folded over like a lid. The lamella is cut with a microkeratome. Recently, a femtosecond laser can also be used here. After the corneal flap has been opened, an excimer laser is used to grind down the inner cornea in such a way that the ametropia is compensated. After this process, the corneal lamella is folded back and pressed. Since it sucks in by itself, it does not have to be sewn on.
This method is commonly used today. It offers advantages for the patient, but it is more difficult for the doctor. An advantage for the patient is that it is not painful. After the operation, there is slight impairment for two to three days and vision is slightly blurred in the first week after the operation. The permanent result can be seen quickly, there is no overcorrection and reading is possible immediately. Wrinkles may appear on the corneal lamella in the first few days. This is remedied by moistening the slat and then laying it back again without wrinkles. Rubbing the eyes can cause the upper corneal flap to shift. Should an epithelium form between the two layers of the cornea, a repeat operation is required. Work can usually be resumed a week after the procedure. If something is not optimal, a painless correction can be made after 3 to 6 months.
The advantages of LASIK surgeries are:
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LASIK surgery is performed on an outpatient basis
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The LASIK operation takes 10-15 minutes in total
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Healing is quick
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The corneal surface is preserved and is only folded, therefore a very good healing process
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No post-operative pain anaesthesia required
Intraocular implantation
In intracular implantation, an artificial lens (ICL) is placed over the eye’s own lens. The artificial lens is attached between the iris and the lens or on the iris. The procedure is comparable to cataract surgery. Corrections of short-sightedness from -8 to -23 dioptres and short-sightedness from +5 to +15 dioptres are hereby possible.
What results can you expect?
The results depend on the starting position. Myopia of up to -8 dioptres can be optimally corrected with the precision of the laser excimer process. In addition, other techniques are more appropriate. Correcting astigmatism (corneal curvature) provides less accurate results. Surgery with an excimer laser of up to +5 dioptres is possible in the case of hyperopia, but the tendency to regression is high. Higher dioptres should be corrected with an intraocular implantation. If the patient also suffers from presbyopia and other factors, it is not always appropriate to completely correct the ametropia.
Are the achievements permanent?
If the ametropia of the patient is stable, i.e. has not increased in the last 2 years, stable results can be expected from the operation. This is one reason why patients under the age of 21 and patients whose ametropia is not stable should not undergo surgery. Presbyopia can already begin at the age of 45. The reduction in the elasticity of the lens then makes it difficult to focus near vision. This loss of accommodation cannot be corrected with refractive surgery.
The difference in vision before and after surgery is amazing.
How does a refractive surgery work?
The procedure is performed on an outpatient basis under a microscope. After preparation, the procedure takes about half an hour and is performed under local anesthesia. During the procedure, the patient will feel the instrument, which prevents the eye from moving. However, he will not feel any pain. After the procedure, the patient can go home without a bandage. Pain in the operated eye may occur after the procedure. Tablets and drops help against the pain. The pain disappears within the first three days.
With the LASIK method, vision is restored quickly. Expect inconvenience for around 3 days. Fluctuations in vision between morning and evening are not uncommon.
With PRK, a longer period of about a week for recovery of distance vision can be expected. Near vision recovery will take longer.
Depending on the procedure and the activity performed, the inability to work can last from 3 to 10 days. After the procedure, the patient can usually do without his glasses.
After the operation, drops that have been prescribed must be instilled into the eye several times. Physical exertion after the operation should be avoided. You should also avoid makeup and visit public pools to avoid risk of eye infection.
Choosing the right surgical procedure
In order to obtain the most accurate knowledge of the eye and its refractive power, a series of examinations must be carried out. This is the only way to choose the right method for the operation.
The LASIK procedure is currently used routinely. PRK must only be used if the cornea is not strong enough or the refractive error is less than 2 dioptres. In the case of severe ametropia, intraocular implantation is used. Combined methods can also be used in the case of severe short-sightedness or long-sightedness in connection with extreme astigmatism. If necessary, both eyes are usually operated on in one session. However, other arrangements can also be made with the doctor.