Background
People with normal vision have the cornea curved in such a way that all the light rays entering the eye are directed toward the retina – the part where light rays are sent to the brain to be interpreted into images. The light rays meet at the right point in the retina so that the image can be formed clearly.
Eye conditions like farsightedness (hyperopia), nearsightedness (myopia) and astigmatism occur because the cornea is too flat, curved or irregular, causing the light rays to meet at the wrong distance from the retina. These conditions are usually chronic, requiring eyeglasses or contact lenses to clarify the vision. If you have any of these eye conditions and you want to improve your vision while decreasing your need for contact lenses or glasses, refractive surgery may be a good option for you.
The most common procedures performed to correct such refractive conditions are LASIK and PRK, where the shape of your cornea – the clear, curved disc at the front of your eye – is altered to fix the curvature and thereby improve your vision.
What are LASIK and PRK?
LASIK (Laser-assisted in situ Keratomileusis) and PRK (Photorefractive keratectomy) are procedures where the curvature of the cornea is restructured to correct your vision. If you are nearsighted, your cornea is too curved, causing the image to appear blurry because the light rays meet before the retina. If you are farsighted, your cornea may be too flat, causing the image to form behind the retina. LASIK or PRK can make your cornea more curved or flat, depending on what your condition requires. If you have astigmatism, some areas of your cornea may be irregularly curved, causing light rays to hit the cornea at multiple points, resulting to blurry vision. LASIK or PRK can also correct astigmatism.
In a LASIK procedure, your ophthalmologist uses either a laser or a blade on your cornea to create a thin flap of tissue. This flap is then lifted so that the computer-controlled laser can easily access the inner corneal layers (the stroma). The laser carefully performs the needed reshaping of the cornea to correct your vision, and then the flap is put back over the cornea to heal in a few days.
PRK has the same outcome as LASIK, the only difference being the way the laser gains access to the inner corneal layer. In PRK, instead of creating a flap, the topmost outer layer of the cornea (the epithelium) is removed to expose the inner layers. Then, like in LASIK, a laser reshapes the cornea to correct the eye condition. The cornea is then allowed to heal and a soft contact lens “bandage” is put over the eye for a few days, promoting re-growth of the outer corneal layer.
Wavefront-guided LASIK is an advancement of the traditional LASIK procedure where specific irregularities in a patient’s eye are also corrected. These irregularities, called higher-order aberrations, may cause symptoms like increased sensitivity to lights, halos, blurry vision and difficulty seeing at night. Wavefront-guided LASIK performs special mapping of the eye to determine any irregularities, so that the LASIK procedure can also correct any higher order aberrations in addition to reshaping the cornea to improve vision.
What Can I Expect Before, During and After My Surgery Day?
If you decide that LASIK or PRK may be a good option for your condition, your ophthalmologist will have to schedule an initial or baseline evaluation to see which procedure is more appropriate for you. PRK is more appropriate in particular patients whose corneas are thinner or for those whom corneal flap complications are a concern.
If you wear contact lenses, you will be advised to stop wearing them a few weeks before your evaluation (around 2 to 4 weeks depending on the type that you use) because they can change the shape of the cornea up to a few weeks after you stop using them. You should also inform your ophthalmologist about any eye conditions in the past or present, and about any eye medications that you have taken or may be taking. Then, your ophthalmologist will walk you through the benefits and risks of the procedure and what to expect during the actual surgery.
On the day of your surgery, you may be given medicines to help you relax. Then, eye drops will be applied to your eye for you not to feel any pain during the procedure. You will lie on your back on a special table below the laser system that performs the procedure, and a lid speculum will be used to keep your eyelids open. You may experience some discomfort and dim vision while LASIK or PRK is being performed, and having blurry vision throughout the procedure is a normal occurrence.
The surgery usually takes less than 10 minutes to perform. After the procedure, an itching or burning sensation in your eyes may be expected. Blurry vision, glare, and halo vision may be normal for a period, too. The surgery is performed on an outpatient basis with no need to stay overnight. In fact, most people leave for home only minutes after having the procedure done. However, it is important that someone else drives you home since the medication given to you can affect your ability to drive.
For LASIK, most people experience clear vision the day after the procedure, for some even immediately after. For a number of patients, it might take a few weeks for vision to completely clear up, and any blurred vision and light sensitivity may be expected. Patients who have undergone PRK may take a few days more before vision is stabilized, because it takes at least four days for the cornea’s epithelial layer to re-grow.
The ophthalmologist will schedule a follow-up visit within a day or two after surgery to ensure that the healing process is going as planned. Meanwhile, there will be eye medications to prevent infection and inflammation.
LASIK or PRK can significantly enhance the quality of life of someone who is dependent on glasses or contact lenses to see. Schedule your appointment today to find out if you are a good candidate!
If you think you are a good candidate for LASIK or PRK, your eye doctor will be happy to discuss any questions and concerns about the procedures. Contact your ophthalmologist today to schedule an appointment!