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PRK (Photorefractive Keratectomy)
The PRK technique is a method which uses excimer lasers that take away microscopic fractions of corneal tissue on the surface through the emission of a cold beam of ultraviolet light.
After having removed the epithelium or outer surface of the cornea, the laser reshapes the corneal surface by flattening it in cases of (nearsightedness) myopia, bending it in cases of (farsightedness) hyperopia, and reshaping it in astigmatism.
With the PRK technique the tissue is taken away with remarkable precision, impossible for a human hand to perform, and equal to 1/3 of a micron (a thousandth part of a millimeter) for each laser emission, and with a productivity not achievable by any other means.
This characteristic is exploited particularly to “reshape” the central corneal curve in such a way that it is possible to eliminate or reduce the refractive defects such as (nearsightedness) myopia, (farsightedness) hyperopia and astigmatism.
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PRK technique, excimer lasers, myopia correction, hyperopia correction
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Laser intervention procedure:
1. Anesthetic drops are instilled in the eye.
2. The patient is made to lie on a reclining bed, under the laser apparatus.
3. A small speculum is placed to keep the eye open;
4. A part of the thin outer surface of the corneal membrane (epithelium) is removed by a smoothing instrument;
5. The central optic center of the eye is marked out with the eye-tracker, while the patient focuses on a small, red luminous light.
6. Laser treatment proper:
- for nearsightedness the laser flattens the corneal curve bringing back the focus of the image on the retina;
- for farsightedness the laser accentuates the corneal curve, refocusing the image on the retina.
- for astigmatism the laser reshapes the corneal curve refocusing all the multiple focal points in a sole focus point on the retina.
7. Medication with drops and application of a therapeutic contact lens; at times a protective shell or a bandage is applied.
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laser intervention procedure
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Surgery with the PRK technique is performed under topical anesthesia (some eyedrops) and lasts a few minutes (about 2/3 minutes as far as the disepithelization is concerned and about one minute for the laser treatment). The operation is painless; and at times the patient feels a small disturbance because of the lid speculum.
The epithelium manages to cover the corneal ablation once again in 3/4 days during which the eye must remain protected by a special fixed corneal lens. During this time there may be a sensation of burning, or that of a foreign body in the eye, with tearing and photophobia. Drops will have to be administered for a length of time according to the doctor’s prescription. Restoration of vision is progressive and fast, though in the first month there may be glares, and a transitory hypercorrection may cause nearsighted difficulties (for nearsighted defects/myopia defects) or of far vision (for farsighted defects/hyperopia defects). |
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surgery PRK technique, sensation of burning eyes
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Contact Us
For particular needs contact Angelo Appiotti’s Perfect Vision Team, with professionalism and courtesy at your disposal.
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