1. Corneal Endothelial Cell Changes After LASIK Using a Femtosecond Laser Minoru Tomita, MD, PhD, Masaru Aoyama, MD, Minoru Tomita, MD, PhD, Masaru Aoyama, MD, Tadayuki Nakamura, MD, Nobuo Nakamura, MD, PhD, Tadahiko Tsuru, MD, PhD Shinagawa Lasik Center, Tokyo, Japan Shinagawa Lasik Center, Tokyo, Japan Shinagawa LASIK Center

2. Purpose LASIK with Femtosecond Laser (FS laser) has been widely performed all over the world. However, the influence of the LASIK with FS Laser on the corneal endothelial cell density (ECD) has not been fully reported yet. In this study, we examined the changes of ECD after LASIK. In addition, we reported the effects of anterior chamber gas bubble (AC-bubble) formed during FS laser operations on ECD. Shinagawa LASIK Center

3. Subjects and Methods: 441 eyes of 225 patients who underwent Intra-LASIK using Intralase FS60 ® (American Medical Optics) were enrolled. The preoperative and postoperative (3 months) ECD was examined by NONCON ROBO FA-3509 ® (KONAN), and pre/post-operative ECD was statistically studied. Pre/post-operative visual acuity and refractive power were also examined. ALLGRETTO WAVE Eye-Q ® 400 Hz (WAVELIGHT) was used for Excimer Laser ablations.

4. Shinagawa LASIK Center Preoperative Data Patients ages: 32.3±7.04 years (Mean±SD) Patients ages: 32.3±7.04 years (Mean±SD) Number of ECD ： 2942±124 cells/mm 2 Postoperative Data 3 Months Postoperative Effective coefficient ： 0.99, Safety coefficient ： 1.05 Mean UCVA: 20/25, Mean BSCVA: 20/12.5 Sphere: -5.00±2.23D, Cylinder: -1.09±0.93D Mean UCVA: 20/12.5, Mean BSCVA: 20/12.5 Sphere: -0.13±0.59D, Cylinder: -0.51±0.32D

5. Shinagawa LASIK Center Correction Formula for the Post-Operative ECD * Power of Figure ： R=1+(1/n)(t 1 ·∆K+∆t·K 2 ) ∆t= t 1 - t 2 ∆K= K 1 -K 2 CD =1/R 2 Uosato et al ： J.Cataract Refract Surg 29:1543-1545: 2003. K: the refractive power of the cornea, n: the refractive index of cornea t: the central thickness of the cornea, CD: the changes of cell density R: the postoperative/preoperative magnification ratio of the image

6. Shinagawa LASIK Center Mean Postoperative (3 Months) ECD After Correction = 2927±117 cells/mm 2 = 2927±117 cells/mm 2 Change of Preoperative/Postoperative ECD -16±102 cells/mm2 Preoperative ECD – Postoperative ECD with compensation with compensation = = Decreased by approx. 0.53%

7. Shinagawa LASIK Center Previous Reports on ECD Changes After LASIK Simoroj et al: J Refractive Surg 2003;19:S237-240. ＊ Mean reduction rate of ECD at 1 year after LASIK: 1.54%. ＊ Mean reduction rate of ECD at 3 months: 1%. Jones et al: Am J Ophthalmology 1998;125:465-471.

8. Shinagawa LASIK Center 1.The mean reduced rate after LASIK with FS Laser was 0.53%. No significant differences on ECD values between Preoperative and Postoperative( with compensated) (t-test: P>0.05) Discussions 2. Although previous findings using microkeratome reported approx. 1.0 - 1.5% decrease in ECD, Intralase using FS Laser has less reduction rate, thus confirmed as a safer method.

9. Shinagawa LASIK Center Aberration of gas bubbles into Anterior Chamber (AC-bubble) Lifshitz T et al. J cataract Refract Surg. 2005: 31: 2227-9. As for the cases with the small corneal diameter, when the laser crosses over the blood vessel around the cornea peripherals, gas gets mixed into anterior chamber.

10. Effects of AC-bubble on ECD 24 eyes of 18 patients who developed AC-bubble during flap preparation with Intralase FS60 were examined. The Preoperative/Postoperative (3 months) ECD was statistically compared. Subjects and Methods Shinagawa LASIK Center We also examined whether AC-bubbles make ECD changes.

11. Comparison of ＥＣＤ (cells/mm 2 ) and AC-bubble AC-bubble(-) AC-bubble (+) Preoperative ECD (cells/mm 2 ) Preoperative ECD (cells/mm 2 ) Postoperative (3 months) ECD (cells/mm 2 ) Postoperative (3 months) ECD (cells/mm 2 ) 2942±124 (n= 441 ) 2927±117 (n= 441 ) 2920±130 (n= 24 ) 2901±120 (n=24 ) No significant differences were observed between the groups of AC-bubble(-) and AC-bubble(+) in terms of ECD before or after LASIK at 3 months (P>0.05) Shinagawa LASIK Center

12. Summary 1.The average decrease of ECD was 0.5% at 3 months after LASIK with FS laser. No significant decrease of ECD was found by LASIK with FS laser. 2.No significant differences were recognized in Preoperative and Postoperative ECD even when AC- bubble was formed during flap preparations with FS laser. Shinagawa LASIK Center Acknowledgments Thank you for good help and jobs. Ms. Tomomi Kanamori, Ms. Yuko Yoshida, and Ms. Naoko Inoue