Photorefractive Keratectomy
Photorefractive Keratectomy, or PRK, is a laser eye surgery to correct a person's vision who suffers from nearsightedness (myopia), farsightedness (hyperopia) or astigmatism. Similar to LASIK, it utilizes an Excimer laser to permanently change the shape of the cornea. One of the predominate differences between PRK and LASIK is the way in which the lasers are used. LASIK first cuts a flap out of the top layer of the cornea and then corrects the cornea with the Excimer laser; because this flap never fully heals, it is potentially susceptible to later damage, although that is a rare instance. PRK and LASEK utilize a different methodology for this operation. In the case of PRK, the flap is not made, thusly the cornea's structural integrity is more intact, but the process is more painful and takes longer to heal than LASIK surgery.
PRK has been approved by the FDA for myopia since 1995 and for hyperopia since 1998.
Contents
Process of Photorefractive Keratectomy
Photorefractive Keratectomy involves, much like LASIK, the reshaping of the cornea. Unlike LASIK which involves removing the inner tissue of the cornea, PRK applies laser energy to change the surface of the cornea. Before surgery you will need to have a careful review of your health and eye history. Then you will need to have a refraction to measure your actual prescription. This will need to be performed with eye drops; in order to get the best measurements. The shape of the surface of your eyes will be mapped using an instrument called a corneal topographer. Finally the thickness of your cornea will be measured using an instrument called a pachymeter.
On your day of surgery, a technician will clean the area around your eyes with a hygienic but gentle cleansing pad. The technician will place a series of drops into your eyes in order to get them ready for your treatment. Some of these drops, antibiotic drops, will prevent germs from entering your eye and therefore help to prevent any possibility of infection. Other drops will be placed in your eyes to lightly numb the cornea so that you are comfortable during your treatment. After you recline on the bed-like chair under the laser, an eyelid holder called a speculum, is gently placed between your eyelids to remind you not to blink. Next the epithelium, a thin, protective layer that covers the cornea, is removed. Since you have had numbing drops placed in your eyes, this will not be uncomfortable, but will feel like a slight pressure around your eyes. The surgeon will instruct you to look at a small light during your procedure. Don't worry if you cannot stay perfectly steady-just do your best. Today's laser technology uses a tracking system which will actually follow your eye movements if you can hold pretty still during your procedure. To correct nearsightedness, farsightedness or astigmatism, your surgeon will use an Excimer laser.
Eligibility
People are best suited for Photorefractive Keratectomy are people with moderate levels of myopia or hyperopia who have corneal abnormalities that make them not best suited for LASIK. However PRK may also be used for people with high prescription levels and for active military personnel.
- Better for thin corneas
- Good for low to high levels of myopia,hyperopia and/or astigmatism
- Good for people in military service
Disadvantages
- Longer healing time
- Longer time for results
Photorefractive Keratectomy is a less used procedure due to LASIK. However, it is still the procedure used when LASIK is not the best choice due to eye irregularities. As with all laser surgery, there is always a risk and side effects like light sensitivity and halos may not go away. It is important to talk with your eye care doctor about the risks in your specific case.
Related Topics
For more information
- EyeCareSource.com's Photorefractive Karatectomy article
- Wikipedia.org's Photorefractive Karatectomy article
