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PRK (Photorefractive Keratectomy) Photorefractive
Keratectomy is currently best prescribed for nearsighted patients. PRK (photorefractive keratectomy), a refractive eye surgery, is similar to LASIK in that both procedures employ a computer-controlled excimer laser to reshape the cornea (the front surface of the eye), in order to change its ability to focus light on the retina of the affected eye. PRK is characterized by a lengthier healing process and more discomfort than LASIK. However, PRK requires less instrumentation and avoids the creation of the flap and its attendant risks. PRK versus LASIK: Comparisons
PRK
is not for everyone. There are a few medical conditions that some people
have that make them poor candidates for this procedure. These conditions
are rare and can be detected during your pre-procedure examination with
what is called a Corneal Map. If a condition exists, it is not wise
to proceed and you will be told. Additionally, a condition brought on by the aging process, called presbyopia, cannot be treated with PRK. Presbyopia is the loss of flexibility of your eye lens. This causes many people to need reading glasses as they get older. However, most people can have PRK. After (these conditions) have been ruled out, there are few impediments to a successful procedure. PRK is approved in the United States for the treatment of -1.00 to -7.00 diopters of myopia. With refinements in software and improvements in ablation profiles, this may increase to up to -10.00 diopters. However, the more tissue removed, the more vigorous the healing response. Therefore, it is more likely that there will be regression of effect and haze and/or scarring. If any of the following conditions apply to you, then you are NOT a good candidate for PRK: •
Pregnancy.
The tests that must be completed before your PRK procedure are: •
Eye History & Examination to determine refractive error,
absence of eye disease and your expectations of the procedure. To make you comfortable and the procedure pain-free, anesthetic drops will be placed in the eye you are having treated. These are repeated a few times over the period of one half hour to make sure your eye is immobile. A speculum is gently placed on your eye to ensure that your eye stays open while the surgeon performs the procedure. There is no discomfort, since the drops placed in your eye prior to the procedure will affect your eye until well after the procedure is completed. The technology varies from clinic to clinic. Depending on the equipment, the surgeon will then place a suction ring on your eye that will hold it steady for the entire procedure. If the first technique is not used, other methods of keeping your eye still will be employed (none of them are painful) and you will be asked to stare straight up at a light in the laser machine. Some machines actually track and follow the pupil. Rather than making cuts in the cornea, the PRK procedure uses an excimer laser to shape an area 5 to 9 millimeters in diameter on the surface of the eye. This process removes only 5-10% of the thickness of the cornea for mild to moderate myopia and up to 30% for extreme myopia - about the thickness of 1 to 3 human hairs. The major advantage of this procedure is that the integrity and the strength of the corneal dome is retained.
Some patients see a dramatic improvement in their vision the first day. For others, vision may be blurry and fluctuate for several weeks to several months. Most patients return to normal activities in 1-3 days. Regular follow-up visits are essential to monitor your progress and ensure that you achieve the best results. A series of follow-up examinations will be scheduled to monitor your progress for up to a year. Normally you will be seen a few days after correction, then for a series of follow-up visits over the next twelve months. Check our news link for recent developements.
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