The chance of having a vision-reducing complication has been documented in a number of clinical studies to be less than 1%. There have been no reported cases of blindness resulting from PRK or LASIK.
While only a very small number of patients experience a complication, all patients have certain expectations. It is vital to make sure that those expectations are realistic, before proceeding with PRK or LASIK.
The most common expectation is to become free of glasses and contact lenses. While it is true that all patients who undergo laser vision correction significantly reduce their dependence on glasses and contacts, most patients will eventually require reading glasses, and some may even require a thin pair of glasses for critical distance activities such as night driving. It is best for you to think of laser vision correction as a procedure that reduces your dependence on glasses or contacts.
UNDER-CORRECTION AND OVER-CORRECTION
There are two phases to your procedure: the surgical phase and the healing phase. Both are equally important to your outcome. The speed of visual recovery, the quality and sharpness of your vision, and your final outcome will be determined by your healing pattern, pre-operative prescription, ocular findings and corneal shape. Typically, distance vision clears first, followed by reading vision.
The more severe your initial prescription, the more correction you will need, the more healing you will require, and the greater the chance you will not be fully corrected in just one procedure. Enhancement procedures usually are performed a minimum of one to four months after the initial LASIK procedure, and a minimum of four to six months after the initial PRK procedure. We estimate that about 10% of patients require a second procedure to enhance their final results. On the other hand, some patients experience an overresponse or over-correction, leaving them somewhat farsighted. In FDA trials, less than 1 % of PRK patients experienced signiflcant over-correction or undercorrection,
Infection rarely occurs since patients receive antibiotic drops both before and after the procedure. Following your prescribed eye drop regimen is very important. Most minor infections are treated easily, but should be treated quickly. The risk of infection is greatest 48 to 72 hours following the procedure. In FDA trials, less than I% of PRK patients experienced infection.
Healing haze is a term for the collagen protein that develops on the surface of your eye following PRK. Almost everyone develops trace amounts of haze. It is invisible to the naked eye and usually patients are not even aware that they have haze. Healing haze clears gradually over the months following your procedure, and can be reduced by using antiinflammatory eye drops. Patients with a history of keloid formation, poor healing, or with high prescriptions, are at greater risk for healing haze and are best treated with LASIK. In FDA trials, less than 1% of PRK patients experienced haze.
Even before having laser vision correction, many people experience poor night vision or night glare such as haloes and starbursts. Night glare is common immediately following the procedure and lasts for about three or four months.
If you treat one eye at a time, or are extremely nearsighted with large pupils, you may notice night glare for a longer period. By the time both of your eyes are treated, or six months have passed, night glare tends to decrease to minimal levels. Some patients may benefit from glasses when driving at night. In FDA trials, this condition occurred in less than 4% of PRK patients. The risk is significantly reduced with LASIK.
LOSS OF BEST CORRECTED VISION
A small number of patients experience a slight loss of visual sharpness following laser vision correction. You may lose the ability to read the bottom few lines of the eye chart which you could read with your glasses before the procedure. In many cases, sharpness improves over a period of six to 12 months. In some instances, patients’ natural vision following the procedure is actually better than their pre-procedure best-corrected vision was. In FDA trials, less than I% of PRK patients experienced a loss of best corrected vision.
CORNEAL FLAP RISKS
While LASIK offers a faster recovery, this procedure does have specific risks due to the creation of a corneal flap. A corneal flap which is irregular, too short, or too thin, can prevent the procedure from being completed. In such a case, the corneal flap is closed, and the eye allowed to heal. Three to six months later, the procedure can be performed.
As long as the corneal flap heals smoothly, patients can achieve an excellent result. However if irregularities in the flap persist, a loss of best-corrected vision may result.
Other corneal flap risks include displacement of the flap and epithelial ingrowth. Epithelial ingrowth means that epithelial cells grow beneath the corneal flap prior to the sealing of the corneal flap margins. Although most cases do not require any treatment, severe epithelial ingrowth can disrupt corneal flap integrity. It is usually treated within one month by lifting the flap and cleaning the area.
PAIN OR DISCOMFORT
There is no pain during the actual PRK and LASIK procedures, but some irritation or discomfort may be experienced after surgery. PRK patients may experience some irritation, sensitivity to light, and watering or swelling of their eyes for a few days following the procedure. For LASIK patients, irritation, if any, usually lasts only for a few hours. A relatively small number of PRK patients experience severe discomfort, which usually can be treated with medication.
Actual outcome data for LASIK is not available because it is currently under investigation by the FDA. Ask your eye doctor for the latest information.