Comparison of Early Outcomes of Topo-Guided PRK With Two Refractive Lasers WCC 2015 San Diego, California Simon P. Holland MB. FRCSC,FRCS,MRCP 1, 2, A, B, C David T.C. Lin MD FRCSC 1, A, B 1. Pacific Laser Eye Centre, Canada 2. U. of British Columbia, Canada Financial Interest:A. Clarion B. Allergan C. Alcon

Wavelight Allegretto (WA) – Features   400 Hz   Gaussian beam profile   Pupil based tracker   12 years experience   Satisfactory recovery of vision after TE PRK   Difficulty with image capture for extreme cases   TG PRK – induces myopia due to hyperopic effect   Requires refractive compensation – TNT, Topographic Neutralization Technique

64 years-old female12 mth post-op UCVA: 20/300 UCVA: 20/30- MR: x75 Rx: Pl-0.50x30 20/40+20/30 CT: 488µmCT: 435µm Pre Op 12 mth Pos Op Subtraction WA TG PRK for Keratoconus Pre Op Subtraction 12 mth Pos Op Pre Op Subtraction

Schwind Amaris (SA) – Features  High speed excimer laser – 750Hz, 1050Hz  High speed pupil tracker – 1050Hz  Static Cyclotorsion Control (SCC)  Dynamic Cyclotorsion Control (DCC)  Sirius Imaging  Aberration Free (MR)  Corneal Wavefront  Custom Ablation Management :

SA Methods  Trans-epithelial TG-PRK with simultaneous CXL (modified Dresden protocol)  N=68 KC eyes with 6 months follow-up  Maximum refractive error corrected to leave minimal residual stromal depth 300um  Evaluation: pre-operative, 1, 2, 3 and 6 months: - uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction (MR), topography and keratometry

SA TG PRK for Keratoconus Pre-operative6 mth post-op UCVA: 20/400UCVA: 20/80+ MR: x105MR: x077 20/50- 20/50 SA Treatment Depth: 51.72µm AW: no autocapture for treatment 12 mth Pos Op Pre Op Subtraction

SA TG PRK CXL for Keratoconus Pre-operative6 mth post-op BSCVA: 20/25- UCVA: 20/40 MR: x090MR: +0.75sph 20/40 SA : µm

Result: WA for KC  290 eyes completed 12 months or more follow-up  50% (144/290) ≥20/40 UCVA  54% (157) BCVA improved ≥ 1 line  29% (84) improved BCVA ≥ 2 lines  6% (16) lost ≥2 lines.  Mean reduction of astigmatism was 1.71±1.68D  Mean spherical equivalent reduced from -2.78±2.65D to -1.22±2.10D

WA: BSCVA Change for KC at 12mth

Result: SA for KC  68 eyes completed 6 months or more follow-up  59% (40/68) ≥20/40 UCVA  91% (62) ≥20/40 BCVA  63% (43) improved BCVA  44% (30) improved BCVA ≥ 2 lines  9% (6) lost ≥2 lines  Mean astigmatism reduction: 1.98±1.75D  Mean spherical equivalent (SE): -3.92±4.02D to -0.40±2.31D (PreOp SE ranged: to 1.88D)

BSCVA Change for KC at 6mth WA vs SA p > 0.05

Conclusion of TG PRK with CXL: WA vs. SA  Early results of Schwind TG-PRK with simultaneous CXL potential as effective treatment for CL intolerant KC patients  SA had almost 60% of the cases had ≥20/40 UCVA and 44% improved BCVA 2 lines or more at 6 mth  Excellent tracking - Cyclotorsion control and defocus  expect better astigmatism result  Relatively user friendly TG: Customization with multiple options  Imaging for treatment possible in extreme cases