1. 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

2. 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

3. 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/cm 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

4. 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

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

6. Singh, Nav OD 6 6

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

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

9. 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

10. 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

11. 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

12. TG CXL PRK for KERATOCONUS
Pre-op: x months post-op
BSCVA: 20/ UCVA: 20/30
RX: x /25 12

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

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

15. -6.25-3.50x100 +0.50-0.50 x 160 20/30 KC – Allegretto PreOp:
12 months PostOp:
x /25
KC – iVIS
PreOp:
x050 20/60
6 months PostOp:
-1.00sph /40
Ectasia
PreOp:
x100
20/80
12 months PostOp:
x 160
20/30

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

17. 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 target
Endothelial damage , delayed epithelialization

18. 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