Laser Surgery to Correct Myopia: A Shocking Conspiracy in Medicine? Posted by Zhao Chengyuan on 2011-03-04 10:51:18 Li Hua, Ophthalmology Department, Yongchuan Hospital, Chongqing Medical University This article is copyrighted by guokr.com. For commercial use, please contact guokr.com. Original Article Address: http://www.guokr.com/article/9734/ The incidence of myopia is very high in China and around the world, and there are few people who have a strong desire to remove their eyeglasses. Laser surgery to correct myopia offers an option to those who have such a desire. However, there have always been rumors about “myopia surgery causes blindness” and “myopia surgery is a scam”. What are the facts? Rumor: A friend of mine underwent LASIK surgery, and afterward his vision regressed dramatically, and he had a lot of irregular astigmatism, and later went to another hospital for examination, and was finally diagnosed with conical cornea. They are aware of the dangers of the procedure (anyone who knows a little about ophthalmology, let alone a doctor, can understand), but they have risked universal condemnation by deceiving their patients and treating their eyes as guinea pigs. The conical cornea resulting from the implementation of LASIK is now considered to be a terminal disease, which can only be solved by corneal transplantation! Why are there still so many doctors with glasses in many hospital eye centers? Why are they letting go of such a good surgery? It wasn’t until a few months ago that I figured out it was a conspiracy! Myopic surgery is the biggest conspiracy in medicine in recent years! Truth: The incidence of myopia in our country and the world is very high, and there are many people who have a strong desire to get rid of their eyeglasses. Laser surgery to correct myopia offers an alternative for those who wish to do so. However, there are persistent rumors about “myopia surgery causes blindness” and “myopia surgery is a scam”. What is LASIK surgery? LASIK, or Laser in Situ Keratomileusis (LASIK), is a surgical procedure performed on the human cornea. Ideally, the eye focuses incident light onto the retina and we can see clearly. However, in myopia, the focus is in front of the retina. Myopia can be corrected by wearing myopia glasses – concave lenses that diverge the light and move the focus back to the retina. Surgical correction of myopia is achieved by changing the refractive structure of the eye to adjust the focus of light. The cornea provides about 2/3 of the refractive power of the entire eye, and it is by changing the corneal refractive index that LASIK surgery is able to correct myopia. The procedure is not complicated to say the least: first, a flap with a tip about 100-180 microns thick is cut on the surface of the central area of the cornea and flipped up, exposing the corneal stroma under the flap, then a high-energy excimer pulsed laser is used to cauterize a certain thickness of the corneal stroma, and finally the flap is capped back to its original position without any need for suturing. The corneal epithelial cells will be completely repaired within 24-48 hours. Immediately after that, their basement membrane, the anterior elastic layer, is also gradually repaired. http://www.guokr/Common_600.com/article/9734/ The incidence of myopia is very high in our country and throughout the world, and the number of people who have a strong desire to remove their glasses is not small. Laser surgery to correct myopia offers an alternative for those who wish to do so. However, there are persistent rumors about “myopic surgery causes blindness” and “myopic surgery is a scam”. What are the facts? Rumor: A friend of mine underwent LASIK surgery, and afterward his vision regressed dramatically, and he had a lot of irregular astigmatism, and later went to another hospital for examination, and was finally diagnosed with conical cornea. They are aware of the dangers of the procedure (anyone who knows a little about ophthalmology, let alone a doctor, can understand), but they have risked universal condemnation by deceiving their patients and treating their eyes as guinea pigs. The conical cornea resulting from the implementation of LASIK is now considered to be a terminal disease, which can only be solved by corneal transplantation! Why are there still so many doctors with glasses in many hospital eye centers? Why are they letting go of such a good surgery? It wasn’t until a few months ago that I figured out it was a conspiracy! Myopic surgery is the biggest conspiracy in medicine in recent years! Truth: The incidence of myopia in our country and the world is very high, and there are many people who have a strong desire to get rid of their eyeglasses. Laser surgery to correct myopia offers an alternative for those who wish to do so. However, there are persistent rumors about “myopia surgery causes blindness” and “myopia surgery is a scam”. What is LASIK surgery? LASIK, or Laser in Situ Keratomileusis (LASIK), is a surgical procedure performed on the human cornea. Ideally, the eye focuses incident light onto the retina and we can see clearly. However, in myopia, the focus is in front of the retina. Myopia can be corrected by wearing myopia glasses – concave lenses that diverge the light and move the focus back to the retina. Surgical correction of myopia is achieved by changing the refractive structure of the eye to adjust the focus of light. The cornea provides about 2/3 of the refractive power of the entire eye, and it is by changing the corneal refractive index that LASIK surgery is able to correct myopia. The procedure is not complicated to say the least: first, a flap with a tip about 100-180 microns thick is cut on the surface of the central area of the cornea and flipped up, exposing the corneal stroma under the flap, then a high-energy excimer pulsed laser is used to cauterize a certain thickness of the corneal stroma, and finally the flap is capped back to its original position without any need for suturing. The corneal epithelial cells will be completely repaired within 24-48 hours. Immediately afterward their basement membrane, the anterior elastic lamina, is also gradually repaired. Risks of LASIK Surgery The skepticism about LASIK surgery in Internet articles centers on the procedure’s effect on the structure of the cornea and the risk of subsequent conical corneas or even blindness. The short- and long-term results of LASIK have proven to be satisfactory. The incidence of late postoperative refractive instability is less than 1%, and does not deteriorate in the short term as claimed in the Internet articles. However, the higher the preoperative myopia, the higher the chance of postoperative complications of visual impairment. The incidence of persistent corneal thinning (swelling and deterioration to so-called cone cornea) after surgery is also less than 1% (references 4-6 report rates of 0.04%, 0.2%, and 0.6%, respectively), and is not a “ticking time bomb” in the body, as claimed in the article. Corneal thickness remaining after LASIK is the key to minimizing the chance of postoperative visual impairment complications. Corneal thickness has been shown to be a major factor in corneal strength. The thicker the residual corneal stroma, the lower the risk of developing conical corneas. In an animal experiment with cat eyes, researchers divided the eyes into four groups for LASIK and PRK (excimer laser keratomileusis). Postoperative measurements of the amount of anterior protrusion on the posterior surface of the cornea confirmed that the thinness of the remaining corneal stroma was the main cause of postoperative anterior protrusion on the posterior surface of the cornea to form a conical cornea as compared to a corneal flap. Currently, the international limit is 250 micrometers, but there is no experimental data to confirm whether conical corneas will definitely occur below this limit, or whether conical corneas will definitely not occur above this limit. Some scholars have studied the safety value of the thickness of the residual corneal stromal bed after LASIK and the stabilization time of the postoperative posterior corneal surface curvature, and found that the central part of the posterior surface of the cornea had different degrees of forward expansion in the early postoperative period after LASIK, and the trend of anterior expansion was more obvious in the corneal stromal bed of the thinner patients, and the posterior surface curvature stabilized in the thicker patients within 1 year or the more obvious the return of the postoperative corneal surface curvature. In all cases, the difference between the postoperative curvature of the posterior surface of the cornea at 2 years after surgery and that at 1 year after surgery was not significant. It is clear that as long as the eye is adequately prepared for surgery, the eye meets the surgical criteria, and sufficient corneal stroma is preserved during surgery, the posterior surface curvature of the cornea will stabilize or even recover over time, and there is no risk of the cornea becoming thinner and thinner, resulting in blindness. Pre-operative evaluation is important to minimize risk Like all other surgeries, LASIK has its own indications and contraindications. Before performing the surgery, the surgeon will conduct a thorough evaluation of the patient’s physical condition. Often, the surgery itself takes as little as ten minutes, while the preoperative examination can take hours or even days. Only eyes that are eligible for surgery can benefit from LASIK while minimizing the risks. Patients undergoing the procedure should have had stable myopia for at least two years, and correction of up to 600 degrees of myopia is more desirable than high myopia. Generally, it is best to be no younger than 21 years of age. Patients with autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, dry syndrome, etc., are not suitable for LASIK. Pregnant and breastfeeding women are not eligible for the procedure. Corneal thickness should be measured prior to surgery. Normal corneal thickness should be between 490 microns and 650 microns. The diameter of the pupil should not be too large, as it is prone to glare and other problems after surgery. In addition, other ocular disorders such as infection and glaucoma should be ruled out. In conclusion, prudent evaluation and strict control of the indications for surgery are the prerequisites for surgical safety. The allegation that “Chinese ophthalmologists are treating patients’ eyes as test subjects by applying LASIK to a wide range of clinical conditions” is unfair. In fact, from Trokel’s animal experiments in 1983 to the first PRK surgery in 1988, excimer laser corneal refractive surgery has been carried out for 23 years. That’s not a short time for a class of surgery. And as any surgery is constantly evolving, so is refractive surgery. In 1995, the FDA approved the use of excimer lasers for myopia correction. LASIK today is not what it was 15 years ago, and there have been significant advances in the effectiveness and safety of the procedure. Laser myopia surgery is also performed in other countries. It is estimated that in 2003 alone, 1.1 million people in the United States underwent LASIK. As for the question, “Why do doctors wear glasses when they don’t do LASIK themselves?” This question is not really surprising. Just as plastic surgeons don’t all need eyelids, nose jobs, breast augmentation and chin reduction, and nut vendors don’t eat chestnuts three times a day, needs come first. Besides, there are doctors who do go for LASIK. Conclusion: Rumor busting. As a surgical procedure, LASIK does carry some risks. A good evaluation before surgery is the key to obtaining the desired results and minimizing the complications of postoperative visual impairment. References: [1] Du Zhiyu, Wu Ningling, Wu Dayong, et al. Analysis of the safety value of corneal stromal bed thickness after excimer laser in situ keratomileusis. Chinese Journal of Ophthalmology, 2004,40:741-744.[2] Li Zhaoxia, Xie Lixin, Hu Longji, et al. Experimental study on the effect of corneal flap and subflap thickness on corneal strength after excimer laser in situ keratomileusis. Chinese Journal of Ophthalmology, 2003,39:150-155[3] Steven E. Wilson. Use of Lasers for VisionCorrection of Nearsightedness and Farsightedness. N Engl J Med 2004;351:470-475 .[4] Randleman JB, Russell B, Ward MA, et al. Risk factors and prognosis for corneal ectasia after LASIK. Ophthalmology 2003; 110:267C275.[5] Rad AS, Jabbarvand M, Saifi N. Progressive keratectasia after laser in situ keratomileusis. J Refract Surg 2004;20:S718CS722.[6] Pallikaris IG,Kymionis GD, Astyrakakis NI. Corneal ectasiainduced by laser in situ keratomileusis. J Cataract Refract Surg 2001;27:1796C1802. original article: scientific squirrel club article “Laser surgery to correct myopia: a medical scam of the century? The Reviewed and authorized by the original authorSpecial thanks to: Golden Grape RumorsOriginally published: A Shocking Conspiracy in Medicine – Myopia SurgeryThis article is copyrighted to guokr.com. For commercial use, please contact guokr.com. Original article at http://www.guokr.com/article/9734/本文版权属于果壳网 (guokr.com). For commercial use, please contact gookr.com.