Laser Eye Surgery 1 Laser Eye Surgery: An alternative to eyeglasses or contact lenses? April N. Cleek East Tennessee State University In partial completion of the requirements of the course Research in Allied Health - ALHE4060 Dr. Masini Fall, 2004 Laser Eye Surgery 2 Abstract Glasses and contact lenses have made an improvement in people’s quality of life by allowing them the vision they other wise wouldn’t have although there are still some limitations with them. People limit their peripheral vision with glasses, because they can’t see outside the scope of the rims. They also can be a bother when it’s raining, or playing physical sports, or swimming. In the 1950’s contact lenses solved some of the inconveniences of glasses, such as self-consciousness, restraints of physical activity, and better peripheral vision. But like anything else it also came with a price—purchase price, maintenance, and time. Still with contact lenses activities such as swimming was still a problem for some and long-term lense wearers could develop an intolerance to them. Then someone had a revelation and decided instead of correcting vision from an external point of view why not correct the problem internally. With that initial thinking and the knowledge of several eye surgeons we now have laser eye surgery to correct nearsightedness, two of those being LASIK, laser in situ Keratomileusis, and PRK, photorefractive keratectomy. Many people still have a fear of laser surgery and will forever live with glasses or contact lenses while others are taking hold of the new technology and embracing life without glasses or contact lenses. I want to look at LASIK and PRK in detail and show how these procedures work and answer the question: Is laser eye surgery a safe alternative to glasses or contacts? Laser Eye Surgery 3 Review of Literature Photorefractive keratectomy (PRK) is an outpatient procedure where the patient is awake and aware through the entire procedure. This process uses an excimer laser to sculpt an area 5-9 mm in diameter on the surface of the cornea. For mild to moderate myopia it only removes about 5-10% of the thickness of the cornea and about 30% for extreme myopia, which is about the thickness of three human hairs. A major benefit of PRK is that its extreme accuracy and specific modifications to the cornea cause little trauma to the eye. The laser used is set at a wavelength of 193 nm thick and can remove a corneal cell layer without damaging adjoining cells. Photorefractive keratectomy is a surgical procedure so it’s outcome cannot be guaranteed. PRK was FDA approved for myopia in 1995, since it is still in the experimental stage, the long term effects are unknown. (www.prk.com 2003) The photorefractive keratectomy procedure is a simple process and takes only a few minutes to perform. Local anesthetic drops are placed in the eye to numb the area, then patient is reclined and a speculum is placed one the eye to keep the eye open. The patient is asked to stare at a light while the doctor performs the correction to the eye. The machine will make a clicking or snapping sound that just means the laser is working and you might smell something similar to burnt hair since the laser is burning or vaporizing the tissue. A contact lens bandage is placed over the cornea to protect it while it heals, usually three days. (www.prk.com 2003) After the procedure, the patient is informed to drink plenty of water, get plenty of rest, stay away from smoky rooms, areas with chemical vapors, and excessively dusty environments. The doctor will prescribe eye drops to help sooth the eye and keep it moistened. Immediately after surgery there will be some discomfort of the eye. The patient may experience sensitivity to light such as halos, hazy, or other unusual light effects. The initial healing time is about 3-5 days Laser Eye Surgery 4 and their vision will stabilize in about 1-2 months with the maximum results in up to 6 months (Caster 1997 p.52). Since most of the fibers in the cornea are in the surface, patients will experience some pain since Photorefractive Keratectomy involves the surface of the cornea (Caster 1997 p.57). Some complications of PRK include infection, delayed surface healing, corneal haze, scarring, and development of astigmatism. Laser in situ Keratomileusis (LASIK) is a bit more involved than PRK. It involves using a special knife and cutting a flap of corneal tissue and removing the targeted tissue and replace the flap. LASIK can be performed for all kinds of nearsightedness. In 1998, 40-45% of refractive surgeries performed across the country were LASIK, which is about 80,000 procedures (Lewis 1998). LASIK is suitable for repairing even the most severe refractive errors and has a faster recovery time than PRK. Most patients see well enough to drive home after the procedure. LASIK has been performed since 1991, but has only been FDA approved since 1999. LASIK is a more comfortable procedure for the patient since recovery time is very rapid. Like with PRK the patient is awake and aware of their surroundings. Anesthetic drops are placed in the eye and a speculum is placed on the eye to ensure that the eye stays open. A suction plate is placed on the eye to hold it stationary. A device will flatten the cornea to create a flap with uniform thickness. The flap is lifted to expose the inner layer of the cornea, which the surgeon will reshape to desired level. The flap is then floated back into position where the natural suction of the eye will keep the flap in place. The patient will wear eye shields for four nights to ensure safety while sleeping. There is less corneal scarring long term with LASIK as compared to PRK, although there is a risk of the hinged flap slipping and healing off center. (www.lasik1.com 2004) Laser Eye Surgery 5 Risks that are involved with PRK and LASIK can be minimal but there have been a few instances of severe eye injury requiring corneal transplant (Lewis 1998). A patient can experience infection and delayed healing which is a 0.1% chance with PRK and even smaller with LASIK. It will cause the patient added discomfort and longer healing process. There is a risk of over correction or under correction since it is almost impossible to predict how your eyes will respond to the laser surgery. With over correction the patient will become farsighted which will require a need for glasses or contacts (which was the reason for the surgery). An under correction will leave the patient still nearsighted but improved from the before vision. The patient will either continue to wear glasses or contacts or go back for “touch-up” or enhancement surgery. Corneal haze is part of the normal healing process in PRK, and is much less significant in LASIK. The halo effect, which can interfere with night driving, is an optical effect that is noticed in dim light. Two risks involved with LASIK but not PRK are flap damage or loss or distorted flap. The flap can come off entirely but can be replaced after the laser treatment or in the distorted flap it can heal irregularly creating a distorted corneal shape. (Lewis 1998) In the Journal of Refractive Surgery, JC Hill discussed an informal survey of 200 patients who had undergone the LASIK procedure. The survey looked at the degree of satisfaction of the patient, the use of glasses after surgery, and any symptoms of light sensitivity. The reported results from this survey were that 95% of patients never wore glasses for distance after surgery, but about 24.5% used reading glasses, which was related to age and presbyopia, the inability for an aging eye to focus on nearby objects. Light sensitivity wasn’t changed in about 73% of the patients and night vision wasn’t a problem for 76% of patients, although 24% said their night vision was worse. Out of the two hundred surveyed one hundred ninety five patients were Laser Eye Surgery 6 satisfied with their surgery and one hundred ninety seven would have the procedure again. Base on these numbers I’d say LASIK is a good procedure, but this is just one survey. (Hill 2002) In an issue of Ophthalmology they discussed an issue of long-term eye irritation associated with LASIK. A study was performed on 48 people who underwent LASIK for myopia, 14 males and 34 females. Through this study they found that after LASIK the surface of the eye was desensitized and it disrupted tear production causing ongoing eye irritation. The lead author of the study, Lisa Battat, M.D., stated, “The cause has not been established, but it may be due to sensitization of the traumatized sensory nerves by inflammatory enzymes released during wound healing” (AAO 2001). The study further reported that fluctuating vision improved after blinking or the use of preservative-free artificial tears. An eight-year follow-up study of PRK for myopia patients was printed in the Journal of Refractive Surgery. This study looked at 55 patients who had undergone PRK. The results of the study showed that changes in myopic regression stabilized in all of the myopic patients within 12 months. Only 13% of the eyes experienced a residual trace of corneal haze after PRK. This study stated that there were no late complications during the eight-year time period. The conclusion drawn from this study was that PRK was a safe and stable surgical procedure in this group of patients. (Pietala, et al 2004) Another study shows that PRK remains stable 12 years after the surgical procedure. A British study is the first study to follow up with PRK surgery patients for more than 10 years after the procedure. The study looked at 68 patients who underwent the procedure in 1990 in the United Kingdom. The study noted a small amount of regression in the first year after the procedure, but stability had stabilized when checked at 6 and 12 years. After 12 years, 94% of the patients had maintained best corrected visual acuity. Lead author of the study said that new Laser Eye Surgery 7 developments of PRK are likely to yield better results than LASIK, while preserving the integrity of the cornea. This study showed that 51% of patients were very happy with their PRK results and only 15% were dissatisfied. The study also found no corneal thinning and no late regression or complications. (Rajan 2004) An article in the Ocular Surgery News talked with a panel of doctors about PRK and LASIK and discussed reasons for choosing one or the other. Dr Michael Knorz, MD thought that LASIK had become so popular since it is a relative painless surgery and vision recovery time is rapid. However he did go on to say that there isn’t a great deal of difference in the longterm visual outcomes of the two procedures. Dr Niels Ehlers, MD performed a study comparing LASIK and PRK for one year, looking at optical aberrations during that time. He found no clear winner between the two surgeries; PRK patients experienced more pain and a longer recovery time whereas there are potential flap complications with LASIK. The ocular aberrations were about the same for PRK and LASIK. His advice was for surgeons to use the technique they were most comfortable with performing. (Gonzalez 2003) Method In researching the outcomes of LASIK and PRK I would go to some area eye centers such as TLC Laser Eye Center and look at the number of patients who have had LASIK or PRK and compare their vision before to surgery to their vision after the surgery and at their check-up six months later. I would also get them to fill out a questionnaire asking them questions concerning their vision and effects of the surgery. I would take these results and look at them closely observing all their comments post surgery. I would use the classic and follow-up design method and plot out the results from the surgeries over a certain period of time. I would look at these designs carefully Laser Eye Surgery 8 and come to a conclusion as to which procedure is the safest and has the least amount of post surgery effects. Conclusion Today’s society is turning toward laser eye surgery as an alternative to glasses or contact lenses. Is this a safe alternative? I looked into two commonly performed procedures, LASIK and PRK, to see how safe the procedure is. From my research I’ve learned that no one has gone blind from these procedures, which is one major concern of the surgery. Studies have shown that long-term effects of the procedure are good up to 12 years, which seems pretty good to me! There are some risks involved with both procedures, but like any other surgical procedure these risks are minimal. I found many sources that agreed with having one of the procedures and very few that disagreed with the procedures. Anyone considering one of these procedures should research into several facilities and the surgeon performing the procedure and not rely solely on affordability. After researching into both procedures I don’t see much difference in the procedures found many doctors who said it is basically preference of doctor and patient in agreement. I believe, after this research I will have one of the procedures done to correct my vision in the near future. Laser Eye Surgery 9 References American Academy of Ophthalmology. (2001, July 2). LASIK patients at risk for long-term eye irritation, study says. [Press release posted on World Wide Web]. Retrieved October 23, 2004 from the World Wide Web: http://www.aao.org./aao/news/release/070201.cfm American Academy of Ophthalmology. (2004, October 5). PRK study finds vision stable after 12 years. [Press release posted on World Wide Web]. Retrieved September 9, 2004 from the World Wide Web: http://www.aao.org./aao/news/release/20041005.cfm Caster, Andrew I., MD, FACS. (1997). The eye laser miracle (The complete guide to better vision). New York: Ballantine Books. Gonzalez, Jeanne Michelle. (2003, April). LASIK, LASEK, PRK: The choice is yours. Ocular Surgery News Europe/Asia-Pacific Edition. Retrieved October 23, 2004 from the World Wide Web: http://www.osnsupersite.com/ Hill, John C., Md, FRCS. (2002, July/August). An informal satisfaction survey of 200 patients after Laser in situ Keratomileusis. Journal of Refractive Surgery, 18(4). Retrieved November 2, 2004 from the World Wide Web: www.journalofrefractivesurgery.com/showAbst.asp?thing=3326 Lewis, Carol. (1998, July/August). Laser eye surgery: Is it worth looking into? FDA Consumer Magazine. Retrieved September 23, 2004 from World Wide Web: http://www.FDA.gov/fdac/features/1998/498_eye.html McFadden, Murray, MD. (2003, August 28). Laser eye surgery-LASIK & PRK. Retrieved September 25, 2004 from the World Wide Web: http://www.prk.com/ Pietila, Juhani, MD, Makinen, Petri, MD, Pajari, Tero, MD, Suominen, Sakari, MD, KeskiNisula, Juno, MD, Sipila, Kalle, MD, et al. (2004, March/April). Eight year follow up of Laser Eye Surgery 10 PRK for Myopia. Journal of Refractive Surgery, 20. Retrieved October 19, 2004 from the World Wide Web: http://www.journalofrefractivesurgery.com/showAbst.asp?thing=7750 Refractive Source. (2003 May 27). Straight info of refractive surgery. Retrieved October 19, 2004 from World Wide Web: http://www.refractivesource.com Slade, Stpehen G., MD, Baker, Richard N., OD, Brockman, Dorothy Kay. (2000). The complete book of laser eye surgery. Naperville, IL: Source Books Inc.