Topography-Guided Photorefractive Keratectomy (TG-PRK) and Simultaneous collagen cross-linking (CXL) in Post-LASIK Ectasia Using 2 High-Resolution Excimer Lasers Simon Holland David TC Lin ASCRS, Chicago, Illinois 2012 No financial interests Updated: Title, Purpose, Methods (2 lasers), Results

Purpose To evaluate the early efficacy and safety of TG-PRK combined with simultaneous CXL in post-LASIK ectasia for correction of irregular astigmatism using the IVIS and Allegretto platforms

Methods Using 2 high-resolution excimer lasers for TG-PRK, modified by TNT (topographical neutralization) - trans epithelial technique (n=17) Riboflavin 0.1% in dextran, until aqueous staining UV irradiation with riboflavin (up to 20 minutes) UV 370 um, 3mW/cm2 - 5.4 J/m2 Hypotonic dextran if <400 um Bandage contact lens, standard post PRK management Symptom scor -pre and post-operative uncorrected visual acuity (UVA), best corrected visual acuity (BCVA), manifest refraction (MR) predictability, safety

TG-PRK with CXL for ECTASIA Original Topography: UCVA: 20/100 Pre-op: -2.00sph BSCVA: 20/20 CT: 553 Singh, Nav OD 4 4

TG-PRK with CXL for ECTASIA 4.5 years post LASIK 8 months post-op UCVA: 20/200 UCVA: 20/20 MR: -1.50-1.25x100 20/30 MR: PL-0.25X180 20/20 CT: 500 Singh, Nav OD 5 5

Singh, Nav OD 6 6

TG PRK CXL for ECTASIA UCVA: 20/400 12 month post-op Pre-op: -6.25-3.50x100 UCVA: 20/30- BSCVA: 20/80 RX: +0.50-0.50 x 160 20/30- Dudzic, Monika OS 7 7

TG CXL PRK for Ectasia 26 years old male LASIK x 5 years 3 months post-op UCVA : 20/60 UCVA: 20/30- MR:+1.00-2.75x125 20/30 MR:Pl-0.75x180 20/25+ CT : 552 CT : 544 Hunt, Brian need pre LASIK details ,topo , blade depth 180 u 8

Results 17 patients completed ≥ 6 months post-operatively 12/17 (71%) had UVA of ≥20/40 9 (53%) gained 2 lines or more BCVA; 1 (6%) lost 2 lines or more Mean reduction of astigmatism 2.56D All but two symptomatically improved Complications included delayed epithelialization No progression of ectasia noted up to 18 mth No significant differences in the small sample sizes iVIS central corneal regularization does not induce as much myopia as the Allegretto when used with TNT iVIS - less gain in BSCVA

Conclusions Early results of TG-PRK with simultaneous CXL using two laser platforms shows promise as an effective treatment for highly symptomatic patients with post-LASIK ectasia All but two had improved symptoms 71% of patients had 20/40 or better UVA More than half gained ≥2 lines of BSCVA 10

TG PRK-CXL Summary – 2 platforms, 2 conditions Analysis KC with Allegretto with iVIS Ectasia with both lasers Patients completed 6 months post-op 99 43 17 UVA ≥20/40 54% 42% 71% Gained 2 lines or more BCVA 32% 9% 53% Average reduction of astigmatism 1.63D 1.17D 2.56D

TG CXL PRK for KERATOCONUS Pre-op: +1.75-4.00x060 12 months post-op BSCVA: 20/30- UCVA: 20/30 RX: +0.25-0.75x170 20/25 12

iVIS TG-PRK with CXL for KC Pre-op 6 months post-op UCVA: CF UCVA: 20/50- MR: -6.50-4.75X110 20/60+ MR: -1.00-1.25x180 20/40- Shi, Yan Bin OS 13

TG PRK CXL for ECTASIA UCVA: 20/400 12 month post-op Pre-op: -6.25-3.50x100 UCVA: 20/30- BSCVA: 20/80 RX: +0.50-0.50 x 160 20/30- Dudzic, Monika OS 14 14

-6.25-3.50x100 +0.50-0.50 x 160 20/30 KC – Allegretto PreOp: 12 months PostOp: +0.25-0.75x170 20/25 KC – iVIS PreOp: -0.50-3.75x050 20/60 6 months PostOp: -1.00sph 20/40 Ectasia PreOp: -6.25-3.50x100 20/80 12 months PostOp: +0.50-0.50 x 160 20/30

Allegretto vs iVIS Induced myopia , larger optical zone Mixed cylinder - smaller optical zone

TG PRK with Cross-linking for Keratoconus and Ectasia: Concerns Thinning an already thin cornea - long term stability unknown Predictability - hyperopic surprises - less than expected even with -1.25 target Endothelial damage , delayed epithelialization

TG PRK with Cross Linking: Impressions Effective in both KC and Ectasia in early studies for highly symptomatic CL intolerant patients Reduce nomogram for TNT in ectasia Topograpgical neutralization techniques mostly effective for correcting for induced refractive error from TG PRK – across platforms and for both KC and ectasia