PRK refractive surgery > Photorefractive keratectomy > Correction and recovery

The photorefractive keratectomy (PRK) is a laser procedure used to correct a low and intermediate short-sightedness and astigmatism. In some special cases it could be used also to correct a higher shortsightedness. The method of PRK refractive eye surgery was used for the first time in 1987 in Western Berlin. When correcting shortsightedness by laser we have to remove the central area of the stroma and this leads to a desired change in the incurvation of the cornea by photoablation with the help of excimer laser. This enables to focus the rays of light again on the retina. When correcting astigmatism, the laser balances irregular incurvation of the cornea by removing the tissue. The procedure is carried out only after the removal of epithelium of the cornea.

During photorefractive keratectomy the patient is lying down. The surface of the eye is perfectly anaesthetized by drops and together with its surroundings it is covered by sterile gauze. During the operation the patient is completely conscious. The patient's task is to fix the eye during the operation as best as he can. The position of the eye is closely monitored by the automatic system (so-called eye - tracker) which is a constituent of the laser device. When small movements occur it adjusts the direction of the laser rays so they will fall on the right place (on the patient´s optical axis).

During the first phase of photorefractive keratectomy the surface layer of epithelium is removed. The upper soft layer of the cornea – the epithelium has a great ability to regenerate. Before the application of laser light it is carefully removed by a surgeon from the place of future treatment. By laser procedure a thin layer of the stroma of the cornea is removed as well. In couple of days after the PRK eye surgery the layer of epithelium regenerates spontaneously and renews perfectly a smooth and lustrous surface of the cornea. The microlayer of stroma, which has been removed by laser, does not regenerate and keeps the new incurvation of the cornea. The laser usually removes around 5-15% of the thickness of the corneal stroma. The structural integrity of the eye is fully preserved. A laser ray thanks to its wavelength does not traverse through the cornea and therefore it does not affect any tissues inside the eye.

After necessary layer of the stroma is removed by laser the surgeon overlays the surface of the eye by a contact lens that protects the eye during the first days of healing. The lens remains in the eye during the day and night for the period of four days.

The time of application of the laser energy is usually shorter than one minute and the duration of whole PRK laser eye surgery of one eye lasts from 5 to 10 minutes. The renewal of sight after the photorefractive keratectomy to the level of fine vision takes a couple of days. The patient is able to see a few minutes after the operation but his vision is blurred. To get the fine vision again the renewal of the surface epithelial layer is necessary. The epithelium heals within 3 to 4 days. Smooth and lustrous surface of the eye after 4 days enables a clear vision. In first couple of days after the PRK surgery the majority of people experience some specific problems related to healing of the surface of the eye.

The examples of such problems are the excessive lachrymation, reddening of the eye and a smaller or greater feeling of cutting or burning of the eye. Some patients experience a real pain during the first post-operative day. During fist days after the PRK laser eye surgery the antibiotic drops and drops which affect the process of healing are used. During the next week after the operation some patients can experience a mild feeling of dry eyes, shattering of light and lowered sharpness of vision in semidarkness conditions and the feeling of circles around bright lights during the night. The problems are more common and more serious in the cases of patients with wide pupil.

The complete stabilization of sight occurs usually during second and fourth month after the photorefractive keratectomy. During this time patients use drops which contribute to a positive reconstruction of the tissue of the cornea. The result of the PRK procedure is to some level influenced by the character of inner healing (the reconstruction) of the tissue of the cornea during the period after procedure. The character and rate of healing are to some degree individually variable. When dealing with lower diopters the influence of individual character of healing can be practically neglected. In the cases of a really serious disorder it can cause a deviation of several diopters from an original intention. In most of the cases it is possible to achieve a satisfying result after one photorefractive keratectomy procedure. In some of the cases it is possible to fine-tune the resulting vision by additional procedure.