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LASIK and PRK |
What are PRK and LASIK?
The two most common laser refractive procedures you may have heard about are PRK and LASIK. Both are laser refractive procedures that correct myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. Both use the excimer laser to reshape the cornea and are highly effective. PRK or photorefractive keratectomy is a procedure by which the laser is used to resculpt the surface shape of the cornea or front window of the eye. It is especially good at treating low to moderate near-sightedness or farsightedness, as well as astigmatism. LASIK or laser assisted in-situ keratomileusis is similar to PRK except that the laser energy is applied just under the surface. A thin flap is created and lifted, and then the laser procedure is performed beneath the flap. The advantage of LASIK over PRK is that rather than having to wait 3-5 days for the surface skin to heal, the cut edge of the flap takes about 1 day to heal. Patients often notice quicker visual recovery, but the end visual result is usually about the same with both procedures. The exception is when treating higher levels of nearsightedness where PRK can sometimes result in slightly more scarring. In these cases, LASIK can provide a better visual result. The disadvantage of LASIK is the added risk of creating and having a flap. The vast majority of patients do fine, but problems with making the flap or with the healing of the flap can occur. Overall these risks are felt to be quite small. |
What to expect from LASIK
The actual procedure takes 10-15 minutes to perform. An anesthetic drop is used to numb the eye. Patients may experience a sense of pressure as the flap is created, but there is no pain associated with the actual laser procedure. After surgery, most notice a foreign body sensation once the anesthetic drops have worn off. Usually by the next morning, most experience a noticeable improvement in the way the eye feels and sees. You will be asked to use eyedrops through the initial healing process and to protect the eye from contaminants and eye rubbing for the first 1-2 weeks. |
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A LASIK flap |
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How well will I see after surgery?
Some patients notice some improvement in their vision immediately after the procedure, but most notice that their vision is blurred. About 80-90% of the visual recovery occurs within the first several days after the procedure. For most, the visual recovery is complete by 1-3 months after the procedure. In various studies, over 90% achieve at least 20/40 or better vision without correction after LASIK. This is legal driving vision and is vision good enough for most sports and most activities. If you ended up 20/40, you might choose to have a thin pair of glasses for night driving or for watching a movie from the back of the theater. |
Will I need reading glasses after LASIK?
Young children possess an amazing ability to focus up close. As we get older, we gradually lose this ability, and by about 40 years of age, many people begin to need reading glasses to see near objects clearly. Many nearsighted individuals have the advantage of being able to take off their glasses to read or see close objects. If the near-sightedness is eliminated with LASIK and if the patient is over the age of 40, then reading glasses will probably be needed. One way to get around this is to purposely leave one eye a little under-corrected or a little nearsighted. This is called monovision since one eye is focused at distance and the other eye is focused at near. Most active people have difficulty if there is too much of a difference between the two eyes, but a small difference is often very well tolerated. This gives one the advantage of being able to read big print on menus at restaurants or to select items off of a grocery shelf without being so dependent on reading glasses. |
How safe is laser vision correction?
Overall, the procedure is quite safe, and the majority of patients do quite well. The wavelength of the excimer laser is such that the laser can only treat the surface and cannot penetrate tissues or harm the internal structures of the eye. The excimer laser is also an extraordinarily precise laser, and if the eye were made out of plastic, we could probably provide a perfect result close to 100% of the time. However the eye is made of living tissue that can heal and remodel, and as different people heal differently, each person will have a slightly different result from the same laser procedure. This creates the possibility of under and over corrections. A small under or over correction will often not be noticeable to you, and a significant one can usually be touched up with the laser. There is a small chance of complications during the procedure. At the time of the procedure if the corneal flap that is created is not ideal, the procedure can be aborted and can usually be reattempted several months later. During the healing process for any flap, problems such as epithelial cell ingrowth or inflammation of the flap can arise. These can also usually be treated. Mild irregularity in the corneal surface may cause blurring of vision, which may correct itself over time or require repositioning of the flap. While the surface skin is healing in, there is a risk for infection. You will be on antibiotic drops, and as long as you do not get something contaminated into the eye such as tap water, the risk of infection is very low. |
Who is a good candidate for LASIK?
LASIK can be used to treat nearsightedness, farsightedness, and astigmatism and to decrease, if not eliminate, a patient's dependence on glasses or contact lenses. Patients who have reasonable expectations from the procedure and who understand that any surgical procedure always has certain risks associated with it are the best candidates for the procedure. Patients may not be candidates if they have certain corneal diseases or collagen vascular diseases, such as rheumatoid arthritis, or significant problems with wound healing. Individuals who are pregnant or nursing are not candidates. Lastly, it is important that your refraction or prescription for glasses or contact lenses is stable and not constantly changing. |
How do I know if I am a good candidate?
Anyone interested in pursuing laser refractive surgery needs a complete evaluation to determine if he or she is a good candidate for the procedure. Often at this visit you are given further information about the surgery and have the opportunity to have your questions answered as well as view the facility. Since LASIK is a permanent surgery, it requires careful consideration, understanding, and planning by you and your physician. |
NEOS wishes to thank: Yunhee Lee, M., MPH for providing this refractive surgery material. |
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Refractive Surgery Education for the Public |
Commentary by Paul Pender, MD |
The website eyesurgeryeducation.com is the product of the Eye Surgery Education Council of the American Society of Cataract and Refractive Surgery. It is the best source of information on LASIK for the public that I have found. The Medical Board is nationally recognized for quality care in cataract and refractive surgery. The section on patient expectations is well-written, given the quest for super vision by the public. The improvement in visual acuity and the reduction of complaints of glare thanks to wavefront guided treatments are discussed. There is no section on Conductive Keratoplasty (CK). Potential candidates for CK should view the website refractec.com. |
What would I want to know if I were considering LASIK or CK?
• Does my exam include all of the elements mentioned?
• Do I have the opportunity to discuss the risks and benefits with the surgeon who is going to do the case?
• Who will be responsible for my post-operative care?
• What are my chances of achieving my goals of excellent uncorrected vision for particular tasks?
• How often, and under what conditions, might I expect to have to resort to glasses for things I do every day?
• Can I safely undergo an enhancement if I do not achieve my goals with my initial surgery?
These are the questions I encounter as a surgeon, and I believe that they must be addressed to optimize the outcomes we seek in terms of the improvement of vision and patient satisfaction. |
I found it interesting that there is a disclaimer for both eye care professionals and for the public. The content of the website is neither a substitute for proper training in surgery, nor a replacement for medical advice. The online world has become fast-paced and at times overwhelming with the extent of information available. What the refractive surgery candidate really needs to know about his or her candidacy can only be obtained through a thorough eye examination and a frank discussion with the surgeon responsible for caring for the patient.
The views expressed are those of the author. |
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