What is Excimer Laser?
Excimer laser is a method used successfully for treatment of refractive defects for over 20 years. Excimer laser is a device which generates an ultraviolet light at 193 nm wavelength using Ar F gas. The laser beam generated by the device eliminates the target tissue with the desired thickness and width.
This results in a permanent change in the cornea layer which corrects myopic, hypermetropic and astigmatic defects. Lasik, Femtolasik Lasek and PRK are various applications of Excimer laser treatment.
What is LASIK? Who is eligible for LASIK treatment?
LASIK is the most commonly used method for treatment of focusing defects. Persons over 18 years of age whose diopter value has remained the same during the last 1 year are eligible for this method. The refractive defect and the structure of the eye must be suitable for Lasik treatment. So, all prospective patients receive a detailed eye examination as well as a series of tests for the cornea layer.
Myopic defects up to 12,0 degrees, hypermetropic defects up to 6 degrees and astigmatic defects can be corrected with LASIK. It is important that the patient stops using contact lenses prior to Lasik treatment. The patients with soft lenses are recommended to stop using their lenses at least one week prior to treatment while this period is at least three weeks for those with hard lenses.
Who isn’t eligible for LASIK?
People with structural corneal defects, keratoconus in particular, people with a cornea thickness below a specific limit, people with severe xerophthalmia, people with diabetes and rheumatic diseases, pregnant and lactating women, people with eye defects such as cataract, glaucoma, infection, etc.
First the cornea layer is anesthetized with 1-2 drop anesthesia. Thus the patient doesn’t feel pain during the operation. A tool known as speculum is placed on the lids to avoid unintended lid movement.
Then, a flat surface is obtained with the vacuum ring and a laceration of nearly 0,12 mm is formed on the cornea with a microkeratom. The fleb formed is lifted and Excimer laser is applied to the cornea layer below. Finally the fleb is placed back and the operation is completed. All these operations are completed within 5 minutes and the patient doesn’t feel pain during the operations.
The eyes are not covered after LASIK application and the patient is advised to rest the eyes during the day of operation. Eye drops are used for the week following the operation. During this period, it’s not recommended to swim, wear make-up or rub eyes severely.
Benefits of LASIK treatment
The most important advantage of LASIK treatment is the comfort of the patient. The LASIK method can even correct higher diopter values effectively in patients whose eye structures are suitable for the method.
Recovery is fast and the patient can experience restored vision within hours following the treatment. Problems such as pain, watering, etc. disappear with 12 hours maximum and the patient can return to work the next day. The eye drops are used for an average of 1 week after the operation.
LASIK is treatment performed on the outermost layer of the eye. So it is unlikely that the inner parts of the eye will be damaged. However, in very rare occasions, there might be some problems during lifting the fleb from the cornea and infections, allergies or failure in correcting the defect can be experienced after the treatment.
These problems vary in direct connection with the doctor performing LASIK treatment and the laser device used. Prior to the Lasik treatment, the quality of the Excimer laser device and FDA approval in particular should be checked. Alcon ALLEGRETTO WAVE® Eye-Q Excimer Laser system used in our hospital operates at 400 Hz and it is one of the fastest laser systems in the world. It can cure 1 diopter defect in less than 2 sec. The laser treatment is carried out safely due to the eye tracker system operating at 400 Hz.
What Are The Refractory (Focusing) Defects?
The eye is an organ which principally resembles a camera. The beams from the outer environment pass through some refractory surfaces such as the cornea (the transparent outermost layer), lens, etc. and focus on the macular area on the retina which is in charge of clear vision. When the beams focus on a different place, this is called a refractory defect.
The refractory defects can be categorized in 3 groups: myopic, hypermetropic and astigmatic. Besides these, presbyopia is the loss of near sight as result of the decrease in focusing feature of the eye lens over 40 years of age. This is not an eye disease but a natural part of the aging process.
The myopia, which can be described as the inability to see far, is result of the beams received by the eye focusing in front of the retina. Most commonly, it develops as a result of the front-rear axis of the eye being longer than usual. It is a structural feature and is frequently genetic.
It usually begins at school age and increases as the process of aging continues. The development of cataract in the older ages may also result in myopia changing the refractory feature of the lanes.
It can be described as the inability to see near clearly. It is a result of the beams received by the eye focusing behind the retina. Unlike myopia, the structure of the eye is smaller than usual. The most frequent causes of the hypermetropia is structural and genetic.
When it is not treated, hypermetropia increases the risk of amblyopia in children. So, all children should have eye examinations prior to school age.
It develops as result of the refractory power of the cornea being different in various meridians. Astigmatism is an eye disease which causes blurred vision at every distance.
It can be structural or develop as result of degenerative diseases, infections and traumas which might cause changes in the cornea.