EyeWorld Asia-Pacific June 2014 Issue

52 EWAP rEfrActivE June 2014 Views from Asia-Pacific Cordelia CHAN, MD Head and Senior Consultant, Refractive Surgery Service, Singapore National Eye Centre 11 Third Hospital Avenue, Singapore 168751 cordelia_chan@snec.com.sg P hotorefractive keratectomy (PRK) took a back seat when laser in-situ keratomileusis (LASIK) emerged to take the refractive world by storm more than a decade and a half ago. The faster visual recovery afforded by LASIK coupled with minimal postoperative discomfort and absence of haze made it popular among both refractive surgeons and patients. Over time, surgeons found that PRK still had a major role to play in excimer laser cornea refractive surgery. Improved methodsof epithelial removal generated “new” procedures like LASEK (epithelium removal with alcohol) and EpiLASIK (epithelium removal by an automated mechanical cleaver), all collectively termed “advanced surface ablations”. These are excellent alternatives to LASIK, especially for patients found unsuitable for LASIK due to a variety of reasons. LASIK is still my preferred choice of laser vision correction, with its faster visual rehabilitation, excellent efficacy and predictability even for higher myopic treatments and astigmatism, and great patient satisfaction. With femtosecond lasers creating these LASIK flaps, better flap thickness predictability, more stable and adherent flaps and less epithelial ingrowth make LASIK safer than before. However, post- LASIK keratectasia is still a bugbear for all refractive surgeons, and in patients with thin corneas or suspicious topographies, surface ablation procedures would be the treatment of choice. Corneal haze is a major consideration in all surface ablation procedures, especially in Asian eyes, which tend to scar more readily. I routinely use mitomycin-C 0.02% for 30 seconds to 1 minute for all my cases, even in low myopic treatments. The upper limit of refractive correction for my cases would be a spherical equivalent of –8.00 DS, as higher corrections are at higher risk of haze. Postoperative pain is also an issue for some patients, but a controlled and tidy removal of the epithelium, a well-fitting bandage contact lens and appropriate oral analgesics have lessened the pain many patients experience after PRK, LASEK or EpiLASIK. Both LASIK and surface ablations will continue to play a major role in laser vision correction. At the end of the day, careful patient selection, proper counseling and management of patient expectations are crucial to the success of any refractive surgical procedure. Editors’ note: Dr. Chan has no financial interests related to her comments. Sri GANESH, MD Chairman, Nethradhama Hospitals Pvt. Ltd. 256/14 Kanakapura Main Road, 7th Block Jayanagar, Bangalore – 560082 Tel. no. +91-80-26088000 Fax no. +91-80-26633770 chairman@nethradhama.org B oth PRK and LASIK are being routinely used to treat myopia and myopic astigmatism. LASIK was the most popular technique because of its wow factor, stability, comfort, and faster healing, but there has been a resurgence of PRK and surface ablation due to the rare but serious complications of corneal post-LASIK ectasia and flap complications. PRK has seen a resurgence in popularity due to many factors such as small Gaussian beam profile in high-speed lasers, which give smooth ablations, and the use of mitomycin Cwhich have reduced the incidence of haze. Also, PRK is technically a much easier procedure to perform and less demanding surgically than LASIK. In our practice, we use both techniques and select the procedure depending upon corneal topography and thickness, myopic error, the condition of the epithelium and surface, and patient activity. For patients with lower myopia (< 5 D spherical equivalent), thinner or borderline corneal thickness, basement membrane dystrophies or epithelial irregularities, and whose activities involve contact sports, we prefer to do PRK over LASIK. Our preferred technique of surface ablation is trans PRK, where the laser (Schwind Amaris) ablates the epithelium and stroma in one go, followed by application of 0.02%Mitomycin C for 20 seconds routinely. This technique is very easy to perform even by novice surgeons and residents and has a very low risk of complications with good clinical outcomes. We also compared trans PRK and alcohol assisted PRK (LASEK) in the contralateral eyes of the same patient. In this randomized , prospective clinical study, 52 eyes of 26 patients with low myopia were treated contralaterally with T-PRK and A-PRK and followed up for 6 months. The time taken for performing T-PRK was almost half of that with A-PRK, with a faster epithelial healing in the T-PRK eyes. Pain score, visual acuity, contrast sensitivity, glare, halos were similar and minimal in both groups. Though the visual and refractive outcomes were comparable between the two techniques, T-PRK is faster and easier to performwith surgical skill, faster epithelial healing, and an all-laser single-step procedure. The main drawbacks of surface ablation today are pain factor, longer use of postoperative steroids with their attendant risks, and the occasional incidence of haze and regression. PRK scores over LASIK in being a safer procedure while being easier to perform. Editors’ note: Dr. Ganesh has no financial interests related to his comments.