Photorefractive Keratectomy

Laser eye surgery is a fairly new method of surgery which is highly effective and has a great safety record. It can be used for correcting a wide variety of visual problems and in many cases it often remove the patient's need to constantly wear glasses. There's two main methods of laser eye surgery, LASIK (laser-assisted in situ keratomileusis) and Photorefractive keratectomy (PRK). The main differences between the two different types of surgeries, is the way in which the middle layer of the cornea, known as the stroma, is exposed before it is vaporised through the use of a laser. PRK was amongst the first commercially available methods of laser eye surgery and was mainly used to treat low refractive errors. PRK is especially suitable for those with large pupils and thin corneas.

The Procedure

Before the procedure you will need to undergo a thorough eye examination in order to find out which method of vision correction you are best suited to. Depending on the results of the exam your doctor may opt for surgery or an alternative treatment. In order to map out your cornea, Corneal topographers are used to take detailed photographs and produce maps of your eye. The topographer identifies any problems in the roundness of your cornea, especially any flatness or steepness which can cause problems with vision and will need to be altered. Before undergoing the surgery you'll have to inform you doctor about any medical conditions you have that could affect the surgery. There are several medical conditions that will disqualify you as a PRK candidate surgery. Similarly some conditions will require a postponement of surgery to a later date.

The Procedure

PRK is typically performed as an outpatient operation, meaning you will be able to return home on the same day. The procedure itself is fairly quick, with the entire operation taking under 20 minutes. General anaesthetic is not used, meaning you will be awake throughout the procedure although some oral sedatives and anaesthetic eye drops may be given to you to ensure that any discomfort is minimal. And most patients don't feel any pain when undergoing the PRK procedure. To begin with, your surgeon will put the laser into place and fits a retainer on your eyes so that they will remain open. Each eye is operated on individually but, due to the anaesthetic drops this won't be uncomfortable. A suction ring is usually used in order to keep pressure on the eye and to help it remain immobile throughout the procedure.

Rather than making cuts in the cornea as in other methods, the tissue is removed from your eyes through use of an excimer laser. A clicking noise will occur throughout the procedure and this indicates when the laser pulses are emitted and it's common to smell an acidic odour as the tissues in your eye are being removed. The process removes a tiny amount of tissue, about the thickness of a couple of human hairs. This helps to keep the strength of the corneal dome intact and through appropriate sculpting, can be used to treat myopia, (shortsightedness) hyperopia (longsightedness) and astigmatism. Once the procedure is finished on one eye, it's typical for you to be asked to rest for a while before the other eye is operated on. And in some cases the second eye can be operated on over a week later.

After surgery

Following surgery, it's important to follow any aftercare advice that you're given. It's commonly recommended that you avoid rubbing your eyes, rest and make sure to take your prescription medications diligently. Your eyes are in a highly vulnerable state following surgery so it's highly important that you take care following the procedure. It's recommended that you have someone drive you home after surgery and that you get ample rest at home. Although you may be able to resume your day to day activities very quickly, it's commonly advised that you take a week off in order to rest your eyes and promote healing. You should also avoid any strenuous exercise for at least a week afterward as this can put unnecessary strain on your eyes which may cause trauma and interefere with the healing process. It's normal to have a number of follow up visits with your surgeon in order to monitor your progress and check for any complications. You may need to wear a special bandage contact lens and apply anti-inflammatory or anti-biotic eye drops for a few weeks after the surgery.

Many patients achieve crystal clear, twenty-twenty vision by using PRK although in a minority of cases results may not be as dramatic. You may still need to wear glasses or contact lenses after the laser correction although your prescription levels should be much better than before the surgery.

The Risks

Although the overwhelming majority of laser correction surgeries are performed safely, as with all surgical procedures, there is a risk of complications arising. These can include excessive tearing, infections or swelling. There's also the slight risk that the outer tissue layer of the cornea will grow back in abnormal way. If the amount of tissue removed was not enough then the results of the surgery may not provide the improvement in vision you were expecting and this is known as under correction. Those who are nearsighted are also at a greater risk of under correction. In order to fix this type of problem, another surgical procedure may be required. Similarly, if too much tissue is removed then your vision can become over-corrected although this is much more difficult to fix than under correction. If an uneven amount of tissue is removed from the eye then it may lead to astigmatism. This occurs when your eye moves too much during surgery and may require further surgery to correct.

Important notice