EyeWorld China September 2019 Issue

Clinical Pearls of Femtosecond Laser Surgery Prof Rohit Shetty FEMTOSECOND LASER SURGERY Surface Ablation on post-SMILE Patients Prof Chen Yueguo Topography-guided ablation can restore the corneal regularity and is a safe and effective method for complicated SMILE cases. In procedure design before enhancement for SMILE, hyperopic shift and uneven epithelial thickness should be considered. Figure4: Post-operative regressionandepithelial thickening 8 Use of small incision lenticule extraction (SMILE) has shown promising results in treatment of refractive errors such as myopia, hyperopia, presbyopia, and astigmatism. SMILE offers advantages such as the ability to perform flapless LASIK and painless PRK. However, no customized cutting pattern, kappa angle and cyclotorsion compensation, steeper learning curve in lenticule dissection, and difficulty in enhancement procedure decision are some of the disadvantages of SMILE. “According to a report published in 2017, about 3% of patients undergoing SMILE need an enhancement procedure within 1 or 2 years. 4 Post- operative complaints in SMILE patients are due to decentration or small optical zone” explained Prof Chen Yueguo. Prof Chen explained through the case of a 20-year old patient with uneventful bilateral myopic SMILE who presented with glare, halo and double image, since post-operative day one. A topography guided LASEK enhancement was performed 23-months post-SMILE, which resulted in reduction of vertical and horizontal coma and spherical aberration within 2-month after the procedure. However, regression was observed over time, and it was believed to be due to epithelial thickening (Figure 4). In addition, post-operative hyperopic shift resulted in over-correction in the dominant eye. Since mitomycin C was not available, a re- enhancement using wavefront optimized (WFO) Wavelight ® EX500 was performed. A significant improvement in UCVA, BCVA and refraction (6 month post-operative: 1.0+; plano and 8 month post-operative: 1.0; plano) was seen without any symptoms of glare and halo, thus showing that topography guided WFO ablation was successful in restoring irregularity of cornea. Safety, precision, versatility and patient comfort are the greatest advantages of femtosecond laser (FS) and it has since established its place in high precision ophthalmic surgery. “Ease of lifting the flap is one of the strongest advantages of using FS 200” said Prof. Rohit Shetty. Prof. Shetty shared clinical pearls on femtosecond laser surgery (Table 4).