EyeWorld India September 2016 Issue

September 2016 56 EWAP refractive consecutive chart review study were 16 eyes of eight subjects with hyperopia after RK who had undergone femtosecond laser- assisted LASIK. When each of these patients was treated, femtosecond power was increased and more spots placed to make it easier to lift the flap, Dr. Rush reported. In all cases the femtosecond flap was successfully created. “We didn’t have any cases of vertical gas breakthrough or epithelial ingrowth. Our refractive outcomes were similar to what you would expect to see in a virgin eye.” Clinical possibilities Dr. Rush is hopeful about what this means clinically. “Just by modulating the settings, we can come up with a good approach to offer patients the great outcomes of LASIK rather than resorting to another refractive technique like PRK or doing another surgery altogether like a refractive lensectomy,” he said. For those looking to create femtosecond flaps for such patients, Dr. Rush advised making these as deep as possible. “That adds more structural integrity to the flap, and it makes it less likely to open up in an RK incision,” he said. In addition, the power setting is key because you don’t want any tissue bridges remaining when you lift the flap. If there are any issues with the flap, Dr. Rush stressed the need for caution. “If ever an RK incision is open or you get vertical gas breakthrough, we don’t recommend proceeding with the treatment because we think it’s a big risk for developing epithelial ingrowth,” he said. If the flap doesn’t seem to cut right, he urged practitioners to refrain from trying Views from Asia-Pacific Hungwon TCHAH, MD Asan Medical Center, University of Ulsan 388-1 Pungnab-dong, Sonapa-fu, Seoul, South Korea Fax no. +82-2-4706440 hwtchah@amc.seoul.kr I t is well known that there is progressive hyperopic shift after radial keratotomy due to mid-peripheral bulging and subsequent central flattening of the cornea. And several attempts to correct progressive residual hyperopia with hyperopic LASIK have been tried. However, most attempts did not show good results because of flap complications, such as flap laceration along prior RK lines, flap necrosis, flap dehiscence, irregular astigmatism, and epithelial ingrowth. 1,2 In the early 2000s, the mechanical microkeratome was used for H-LASIK of residual hyperopia in post-RK patients. Then, since the mid 2000s, the mechanical microkeratome flap has been replaced by the femtosecond laser flap. The flap complications with the femtosecond laser flap H-LASIK seemed to be less frequent compared with mechanical microkeratome flap H-LASIK, but still significant numbers of cases of flap complications were reported. 3-5 Recently, the favorable results of the femto flap H-LASIK in post-RK patients were reported. Several studies showed that there was less frequent flap lacerations, and even when the flap lacerated, the laceration was only limited to its periphery, with minimal epithelial ingrowth that was self resolving. It was, probably, because of the better quality of the femtosecond laser, thus, making clean flap making, controlled the thickness of the flap and minimal manipulation of the flap. 6-8 Dr. Rush’s report is very promising. He reported that LASIK flaps were able to be successfully created in 100% pf post-RK patients, although his experience was limited to a small number, just 16 cases. He adjusted the laser settings, increased laser power, and decreased spot separation to make a clean separation of the flap from the bed without tissue bridge and to avoid gas breakage through previous RK lines. He also used a thicker flap. It seems that he clearly demonstrated how to make a clean flap in case of complicated corneal surface such as in the post-RK cornea. The modification of the laser settings, increased laser energy and decreased spot separation, and careful manipulation of the flap may be key factors to prevent flap laceration. However, one thing to remember is that more energy, more inflammation. So, there might be higher chance of having DLK or other types of inflammation after the procedure, which might need stronger anti-inflammatory eyedrops, such as steroids. One last thing to remember is that additional H-LASIK in the post-RK cornea, which is already compromised in its integrity from RK, could further damage its integrity, inducing ectasia. 9 It can happen even 10 years later. Long-term follow-up of these patients may be needed to evaluate its effect on corneal ectasia. Therefore, a rather careful and conservative approach to the post-RK patient seems to still be the mainstream approach. References 1. Francesconi CM, Nose RA, Nose W. Hyperopic laser-assisted in situ keratomileusis for radial keratotomy induced hyperopia. Ophthalmology . 2002;109:602-5. 2. Lyle WA, Jin GJ. Laser in situ keratomileusis for consecutive hyperopia after myopic LASIK and radial keratotomy. J Cataract Refract Surg . 2003;29:879-88. 3. Munoz G, Albarran-Diego C, Sakla HF, et al. Femtosecond laser in situ keratomileusis after radial keratotomy. J Cataract Refract Surg . 2006;32:1270-5. 4. Munoz G, Albarran-Diego C, Sakla HF, et al. Femtosecond laser in situ keratomileusis for consecutive hyperopia after radial keratotomy. J Cataract Refract Surg . 2007;33:1183-9. 5. Perente I, Utine CA, Cakir H, et al. Complicated flap creation with femtosecond laser after radial keratotomy. Cornea . 2007;26:1138-40. 6. Leccisotti A, Fields SV. Femtosecond-assisted laser in situ keratomileusis for consecutive hyperopia after radial keratotomy. J Cataract Refract Surg . 2015;41:1594-601. 7. Rush SW, Rush RB. One-Year Outcomes of Femtosecond Laser-Assisted LASIK Following Previous Radial Keratotomy. J Refract Surg . 2016;32:15-9. 8. Rush SW, Rush RB. Femtosecond Laser Flap Creation for Laser In Situ Keratomileusis in the Setting of Previous Radial Keratotomy. Asia Pac J Ophthalmol (Phila) . 2015;4:283-5. 9. Phelps PO, Tran AQ, Nehls SM. Complication Following Radial Keratotomy and LASIK. Ophthalmology . 2015;122:1172. Editors’ note: Dr. Tchah declared no relevant financial interests. Femtosecond - from page 55