EyeWorld Korea June 2019 Issue

22 EWAP JUNE 2019 experience in the surgical technique at a Zeiss-Approved training centre, which in his case was in India. In reviewing his first 200 eyes, Dr. Hamid used a control group of femtosecond LASIK (Femto-LASIK) eyes for comparison, matching the two groups as closely as possible. They compared unaided distance visual acuity (UDVA) and near visual acuity, spherical refraction, and fluorescein tear breakup time. Patient satisfaction data also were collected. There was no statistically significant difference in UDVA be- tween the two groups, with 94.3% (199/211) of LASIK eyes and 95.9% (116/121) of SMILE eyes achieving 20/20 or better binocular UDVA at 3 months. SMILE also was comparable to LASIK in terms of predictability and ocular surface performance, with 87.9% (391/445) of LASIK eyes and 90.4% (197/218) of SMILE eyes achieving spherical equivalent refraction within 0.5 D. Reported patient satisfaction was high in both groups. There was no statistically significant difference in tear breakup time. These results demonstrate that ZEISS’s structured training program can produce excellent visual results within a safe and ethical environ- ment, Dr. Hamid concluded. Patient selection Following Dr. Hamid, S.K. Sundar- amoorthy, MD , detailed his process for selecting candidates for SMILE. As with any refractive proce- dure, Dr. Sundaramoorthy said that patient selection is essential for success with SMILE. Careful patient selection ensures that the procedure achieves results-based patient satis- faction and stable refractive correc- tion while preventing complications and excluding unsuitable patients. SMILE is the first choice for very active and busy patients who travel for business, want to return to work early, do not want to risk flap displacement, and generally prefer a treatment that provides the chance to have less impact on their lifestyle. SMILE, based on a flapless surgical principle, has to potential to be well suited for patients who engage in extreme or contact sports, are in the military or law enforce- ment, or those who work as com- puter professionals or professional night drivers, Dr. Sundaramoorthy said. It seems to be ideal to know pa- tients well and to understand their visual needs and whether the attain- able level of satisfaction is accept- able to them, Dr. Sundaramoorthy said. Patients should be educated about the benefits as well as the risks and side effects of the proce- dure, Dr. Sundaramoorthy said. Dr. Sundaramoorthy selects patients who are 18 years old with a stable refraction for 1 year and with an acceptable yearly change of < 0.50 D that can be verified with old prescriptions. He also consid- ers whether a patient has a family history of myopic complications. Other considerations are systemic conditions such as anxiety, uncon- trolled diabetes, skin or autoim- mune diseases, the use of drugs, and phobias. Pregnancy and nursing should be verified—he recommends waiting two menstrual cycles after delivery or 1 month after nursing is stopped. The eye’s anatomy and condi- tion should be carefully evaluated in terms of the brow and nose, set of orbit, palpebral fissure, and the presence of lid abnormalities or pterygium. The cornea should be evaluated for size and thickness, scars, dystrophy, and infections, and the patient should be evaluated for chronic allergic conjunctivitis, cataract or subluxation, glaucoma, and retinal pathologies, Dr. Sundar- amoorthy said. Dr. Sundaramoorthy selects patients whose mesopic pupils are < 6 mm; have a cycloplegic versus manifest refraction < 0.75 D; have an angle kappa < 5˚; have HOA – RMS 0.3 μm; and have a vertical coma < 0.15 μm. Dry eye and contact lens warp- age should be managed before the procedure. Exclude patients with suspicious or early keratoconus, forme fruste keratoconus, a family history of corneal pathology, or pellucid marginal degeneration, Dr. Sundaramoorthy advised. Corneal thickness should allow caps of around 110 to 120 μm and a residual stromal thickness of a minimum 250 μm. SMILE vs. transPRK Deng Yingping, MD , conducted a comparative analysis of the visual results following the treatment of low to moderate myopia with SMILE versus transPRK. The two procedures represent corneal stroma and surface refractive surgery, re- spectively, highlighting the devel- opment toward greater comfort, safety, and accuracy, with further improvement in visual acuity and reduction of complications. The comparative analysis was a prospective case-controlled study on 47 SMILE cases (94 eyes) and 22 transPRK cases (44 eyes). Uncorrected distance visual acu- ity, best corrected distance visual acuity, spherical refraction, con- trast sensitivity, HOAs, modulation transfer function (MTF), and Strehl ratio were evaluated, and patients were administered the Quality of Life Impact of Refractive Correction Questionnaire. There was no statistically significant difference between the two groups in terms of uncorrected visual acuity, refraction, and HOAs, but a statistically significant differ- ence was seen for the MTF (total MTF of 0.54 ± 0.11 with SMILE and 0.43 ± 0.11 with transPRK, P<0.05), Strehl ratio (total SR of 0.14 ± 0.05 with SMILE and 0.11±0.08 with transPRK, P<0.05), contrast sensi- tivity (P<0.05), and visual quality rating scale (P<0.05). Predictive modeling in SMILE I s there a way to predict whether a cornea with a normal-looking to- pography will have normal healing or progress to ectasia after refractive surgery? Predictive modeling can help determine whether a patient is suitable for a particular refractive procedure, Rohit Shetty, MD , said. Research on biomechanics after various refractive procedures has been done previously. To produce their prediction model, Dr. Shetty and a group of mathematicians looked at every component of the procedure. In each of the study’s 25 participants, Dr. Shetty performed LASIK in one eye and SMILE in the other. They paused each procedure after the initial flap cut and cap cut for 4 hours and evaluated the corne- al biomechanics at the end of that time period before proceeding with flap lift and ablation and lenticule removal. Patients were followed up at 1, 7, and 30 days after the procedure. In LASIK eyes, the flap cut caused corneal biomechanical changes in 37% of the indices. In contrast, in SMILE eyes, the cap cut caused changes in only 13% of the indices. This indicates that, as expected in theory, there is a large change in corneal biomechanics just with the creation of a flap. Dr. Shetty’s study provides data for the contribution of the flap or cap cut and ablation separately. It also demonstrates a significant difference in biomechanics after the flap cut but not after cap cut and allows for a better understanding of the improved biomechanics report- ed in SMILE, in turn allowing for better predictive modeling. Clinical outcomes of SMILE after retinal detachment surgery Sung Min Kim, MD , Nunemiso Eye Clinic, Seoul, South Korea, said that various complications can occur during any refractive proce- dure due to high suction pressure. These range from relatively mild complications such as conjunctival hemorrhage to disastrous unilateral simultaneous retinal detachment during laser cutting. However, SMILE is known to be much safer because of the curved contact lens used by the VisuMax femtosecond laser, with only low suction needed to immobilize the eye, allowing lower, more stable pressures during the procedure. To evaluate this, Dr. Kim and colleagues conducted a study on the long-term clinical outcomes of SMILE after previous retinal detach- ment surgery. They also evaluated the safety of the low and stable suction system used in SMILE. They performed a simple case review of two eyes in two subjects who had undergone scleral buckling and cryotherapy prior to SMILE, evaluating results up to 6 months. The second case was evaluated as having a moderate risk of ectasia, hence SMILE Xtra (OFF Label) was performed. Based on these cases, Dr. Kim concluded that SMILE and SMILE Xtra (OFF Label) did not aggravate postoperative retinal status. With proper use, the low and stable suc- tion system used in SMILE allows for a safe procedure for patients with previous scleral buckling and cryotherapy. Scleral buckling and cryotherapy prior to SMILE and SMILE Xtra (OFF Label) did not affect long-term clinical results. Dr. Kim and his colleagues be- lieve that a surgical history of scleral buckling is irrelevant to the visual and refractive outcomes of SMILE. SMILE and SMILE Xtra (OFF Label) may be safe and effective modalities to correct myopia and myopic astig- matism in patients with previous retinal detachment surgery. SMILE, LASEK, LASEK-CXL for thin corneas LASIK is effective for the correction of myopia and has an excellent ability to correct refractive error. However, there is a risk of ectasia in patients with thin corneas because of insufficient residual stroma after surgery. Thus, a central corneal Shaping Tomorrow’s Vision: SMILE and SMILE Some More Supplement to EyeWorld Asia-Pacific June 2019