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

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

TG-PRK with CXL for ECTASIA4.5 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

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-

TG CXL PRK for Ectasia 26 years old maleLASIK x 5 years 3 months post-opUCVA : 20/60 UCVA: 20/30-

MR:+1.00-2.75x125 20/30 MR:Pl-0.75x180 20/25+CT : 552 CT : 544

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

TG PRK-CXL Summary – 2 platforms, 2 conditions

AnalysisKC

with AllegrettoKC

with iVISEctasia

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-opBSCVA: 20/30- UCVA: 20/30 RX: +0.25-0.75x170 20/25

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-

iVIS TG-PRK with CXL for KC

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-

KC – AllegrettoPreOp:

+1.75-4.00x060 20/30-12 months PostOp:

+0.25-0.75x170 20/25

KC – iVISPreOp:

-0.50-3.75x050 20/606 months PostOp:

-1.00sph 20/40

EctasiaPreOp:

-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