1. World Cornea Congress VII – Electronic Poster Season Tse Wing Yeung, MBBS, FRANZCO Ronan Conlon, MD; Joshua Teichman, MD, FRCSC; Setareh Ziai, MD, FRCSC; George Mintsioulis MD, FRCSC; Kashif Baig, MD, MBA, FRCSC The University of Ottawa Eye Institute Dr. Baig is a consultant for Alcon, Allergan, Bausch & Lomb, Labtician. Dr. Yeung, Dr. Conlon, Dr. Teichman, Dr. Ziai, Dr. Minsioulis have no financial interests in the subject matter of this presentation.

2. Introduction  Visual rehabilitation post-penetrating keratoplasty (PKP) can be difficult due the the high magnitude of astigmatism (up to 5D), which may not be correctable with glasses or contact lenses (38%) 1  A number of corneal techniques have been described to address this problem including astigmatic keratotomy (AK)  The precision and accuracy of arcuate incisions in AK have significantly improved with the incorporation of femtosecond laser technology  Recent case reports have shown that femtosecond laser-assisted intrastromal astigmatic keratotomy (FISAK) is efficacious in the management of astigmatism in PKP patients 2 1.Cleary, C et al. (2013) Cornea 32:54-62 2.Viswanathan, D (2013) JCRS 39:1916-20

3. Purpose  The purpose of this study is to report the outcomes of the correction of astigmatism with femtosecond laser-assisted intrastromal astigmatic keratotomy (FISAK) in patients with previous PKP

4. Methods  Prospective non-randomized interventional case series  Inclusion criteria: Patients who had significant astigmatism following PKP Complete suture removal at least 1 month prior to the procedure Contact lens intolerance Stable refraction  Paired intrastromal arcuate incisions were created with a femtosecond laser (IntraLase™; AMO)  Multiple postoperative visits were scheduled during the 6- month follow up period

5. Methods At each study visit, data as outlined were recorded: uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), slit lamp microscopy, IOP, manifest refraction, corneal topography, and anterior segment OCT The primary outcomes of the study were postoperative UCVA and BCVA The secondary outcomes were the reduction of refractive and topographic cylinder Intra-operative and postoperative complications were also documented

6. Results - Demographics AgeEyeUCVABCVASphere (D)Cylinder (D)Topographic Astigmatism (D) 124OS20/10020/20-3.504.506.2 271OD20/20020/30-11.258.004.9 369OS20/6020/25-3.005.254.5 440OD20/4020/25-5.755.005.1 533OS20/5020/15-5.756.005.8 675OD20/15020/25-6.507.007.1 769OD20/5020/255.004.3 887OD20/8020/25-6.004.003.5 987OS20/15020/40-8.255.005.6 1055OS20/25020/30-12.258.0012.0

7. Results  Ten patients were recruited (M:F = 6:4)  No serious adverse events were reported  At the 6-month follow up:  Improvements in both mean UCVA and mean BCVA were recorded  A statistically significant decrease in mean refractive sphere was observed:  -5.67 + 3.00 D  -4.33 + 3.44 D (P=0.01)

8. Results  For mean refractive cylinder:  At the 1-month follow-up, mean refractive cylinder reduced from:  5.52 + 1.27 D   3.55 + 1.90 D (P<0.001)  At the 6-month follow-up, the reduction in mean refractive cylinder continued:  5.52 + 1.27 D  2.67 + 1.61 D (P<0.001)

9. Results Diopters Patients

10. Results  For mean topographic cylinder:  At the 1-month follow-up, it decreased from:  5.22 + 1.08 D   4.37 + 2.42 D (P<0.001)  At the 6-month follow-up, it continued to decrease:  5.22 + 1.08D  3.23 + 1.22 D (P<0.001)  There were no statistically significant changes in other topographic measurements

11. Results Patients

12. Conclusions  FISAK is a precise, effective, and safe technique in the treatment of high magnitude of corneal astigmatism in post PKP patients  A statistically significant reduction in mean refractive sphere was observed 6 months post FISAK  Significant improvements in both refractive and topographic cylinders were noted early postop, which continued to decrease at the 6-month follow-up  Intrastromal incisions provide a rapid postoperative recovery and an excellent safety profile