EyeWorld Asia-Pacific September 2017 Issue

September 2017 EWAP FEATURE 17 Views from Asia-Pacific Cordelia CHAN, MD Consultant Eye Surgeon, Eye Surgeons @ Novena, Mount Elizabeth Novena Specialist Centre, Singapore Visiting Senior Consultant, Singapore National Eye Centre, Singapore 11 Third Hospital Avenue, Singapore 168751 LASIK: Now better than ever LASIK technology has evolved over the years, and we are now looking at a mature technology that is safe, efficacious, predictable, stable, and with an extremely high level of patient satisfaction. In a 2016 publication by Price et al. in Ophthalmology , they concluded that current LASIK technology resulted in higher levels of patient satisfaction than contact lens wear. How has LASIK become better? Improvements in excimer laser technology The first and second generation excimer lasers have been replaced with more advanced flying- and variable-spot lasers, with compensation for fluence projection and reflection errors. The newer lasers have better eye-tracking mechanisms, improved ablation profiles with larger optical zones, are less tissue hungry, and provide options for aspheric, wavefront-guided and topography-guided treatments. The result is improved efficacy and predictability, less regression, less induction of higher-order aberrations and fewer night vision disturbances. The femtosecond laser for flap creation The advent of the femtosecond laser for flap creation was a milestone in LASIK evolution. Although many of us LASIK surgeons enjoyed years of good outcomes with the mechanical microkeratome, the femtosecond laser made LASIK safer and more predictable. Key advantages afforded by the femtosecond laser include better flap thickness predictability, the ability to create planar, thinner and customizable flaps, more adherent and stable flaps, and most importantly fewer and less devastating intraoperative complications. Improved topography, tomography, and other screening systems The safety of LASIK has been further enhanced by the heightened ability to identify patients at risk of post-LASIK ectasia, which is a rare but devastating postoperative complication. Improved topography and tomography screening systems, a better understanding of corneal biomechanics and its assessment and the development of several risk scoring systems have helped identify patients “at risk” of ectasia. How good is LASIK compared to other refractive surgical procedures? Surface ablation procedures (PRK, LASEK, and epiLASIK) are associated with good outcomes. However, postoperative pain, the risk of haze, limited use in high myopic and astigmatic treatments and an overall increased “downtime” are the main disadvantages. Phakic intraocular lenses (i.e. implantable contact lenses (ICLs)) give excellent vision, but the risks involved with an intraocular procedure should never be underestimated. Small incision lenticule extraction (SMILE) is probably LASIK’s biggest competitor, but until the issue of delayed visual recovery is addressed, SMILE will not surpass LASIK in terms of efficacy and popularity. Besides, in SMILE, wavefront- or topography-guided treatments are not possible, and the current platform does not provide cyclotorsion compensation. Conclusions Advances in excimer and femtosecond laser technology coupled with improved diagnostics for patient selection have improved LASIK outcomes to the high standards afforded by the procedure today. LASIK has been and will continue to be the refractive surgical procedure of choice in my practice. References 1. Price MO, Price DA, Bucci FA Jr, Durrie DS, Bond WI, Price FW Jr. Three-year longitudinal survey comparing visual satisfaction with LASIK and contact lenses. Ophthalmology 2016;123:1659-55. 2. Yuen LH, Chan WK, Koh J, Mehta JS, Tan DT, SingLASIK Research Group. A 10-year prospective audit of LASIK outcomes for myopia in 37,932 eyes at a single institution in Asia. Ophthalmology 1010;117:1236-44. 3. Sandoval HP, Donnenfeld ED, Kohnen T, Lindstrom RL, Potvin R, Tremblay DM, Solomon KD. Modern laser in situ keratomileusis outcomes. J Cataract Refract Surg . 2016; 42:1224-34. 4. Agca A, Demirok A, Yildirim Y, Demircan A, Yasa D, Yesilkaya C, Perente I, Taskapili M. Refractive lenticule extraction (ReLEx) through a small incision (SMILE) for correction of myopia and myopic astigmatism: current perspectives. Clin Ophthalmol . 2016; 10:1905-12. Editors’ note: Dr. Chan is a consultant for Alcon (Fort Worth, Texas), Johnson & Johnson Vision (Santa Ana, California), Nidek (Gamagori, Japan), and Santen (Osaka, Japan). WANG Zheng, MD Professor of Ophthalmology, Aier School of Ophthalmology, Central South University 191 Huanshi Dong Road, Guangzhou, China Tel. no. +86-20-66289988 gzstwang@gmail.com S ince first reported in 1991 , LASIK has been the most performed , most satisfactory , and most studied among all elective surgeries in the past 26 years. During this time , LASIK has evolved tremendously. As mentioned in the article , technologies such as customized ablation , active eye tracking with iris registration , and wavefront-optimized ablation profiles have pushed LASIK results to a new limit. In the meantime , patients ’ expectations have also been raised. In addition to good visual acuity , nowadays patients desire fast recovery , minimal discomfort , and good night vision. Many studies have shown that the satisfaction rate is very high. However , considering the large patient population , the 3-5% unhappy rate will translate to a big number. The adverse events are often exaggerated by negative press and this can cause an impact on the patients’ confidence in refractive surgery. There ’ s still room for further advances. Preoperative screening is an important part of LASIK. More sophisticated diagnostic technology may help further reduce the risk of LASIK. For example, by using corneal tomography incorporated into biomechanical examinations , it is likely that preclinical keratoconus is screened out earlier, before any topographical abnormalities are detected. Topography-guided LASIK in virgin eyes has shown superior results, with many patients seeing better than their best- corrected before surgery, and having better night vision. All-femto laser small incision lenticule extraction (SMILE) is gaining popularity in recent years. Over 320,000 SMILE procedures have been done in China alone. This novel procedure is “flapless”, so there won’t be problems with flap dislocation after surgery. However, it can still have complications similar to flap-related ones in LASIK, such as diffuse lamellar keratitis, central toxic keratopathy, epithelial ingrowth, and interface fluid syndrome. Other issues include relatively slower recovery and centration and torsional errors during docking. The theoretical biomechanical advantage is yet to be verified by more clinical data. Currently, there’s no topography- or wavefront-guided treatment abailable with SMILE. So there’s long way to go until SMILE is perfected. Although modern LASIK has been very safe and effective, the pursuit is not over, and will never be. I believe LASIK will continue to be the mainstream of refractive surgery for a while. Is SMILE the future? Maybe. More clinical studies are needed, of course. So are the advances in femtosecond laser technology itself. Editors’ note: Dr. Wang declared no relevant financial interests. continued on page 18 “ Although modern LASIK has been very safe and effective, the pursuit is not over, and will never be. ” - Wang Zheng, MD