1. Collagen cross-linking (CXL) for keratoconus (KC) with simultaneous topographical-guided photorefractive keratectomy (TG-PRK)
Simon Holland, MD, FRCSC, FRCS(Eng), MRCP, FRC Oph
David TC Lin, MD, FRCSC
Pacific Laser Eye Centre
UBC Dept of Ophthalmology
ASCRS, San Diego 2011
*No financial interests

2. Purpose and Methods
To evaluate early results of efficacy and safety of simultaneous TG-PRK (Custom TNT) with CXL in contact lens intolerant KC using the Wavelight Allegretto laser
105 eyes of 72 patients
Target: or maximum correction of astigmatism if insufficient thickness
Minimal predicted residual stromal depth 320microns

3. Methods Epithelial removal by trans-epithelial laser
Topography-guided PRK with TCAT software (Custom TNT), modified by refraction and proprietary protocol
Riboflavin 0.1% in dextran, repeated drops until presence of aqueous staining
Hypotonic dextran if <400 um
UV irradiation with additional drops of riboflavin (up to 20 minutes)
UV 370 um, 3mW/cm J/m2
Bandage contact lens, standard post PRK
management
Data not able to tell us what effect over time is from CXL. Simon’s impression is that any anticipated hyperopic shift of about 1d that others describe isnt really happening. In theory though that’s why they target -1.25D
Major source of experience is how to adjust Rx based on epithelial breakthrough. If it happen early they will dial back the Rx. Danger is unrecognised breakthrough and perforation.

4. TG PRK X-Linking for Keratoconus
20 year-old male 11 months post-op
UCVA: 20/ UCVA: 20/50
Pre-op: x075 Rx: x080
BCVA: 20/30 BCVA: 20/30
CT: CT: 412 4 4

6. TG PRK X-Linking for Keratoconus
19 year-old male months post-op
Pre-op: x075 UCVA: 20/25
BSCVA: 20/30 Rx: x /20
CT: CT: 447 6 6

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

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

12. Results 32 eyes completed 1yr follow up
22 (70%) had ≥20/40 or better uncorrected vision (UCVA) at six months; all had BSCVA of 20/40 better
4 eyes lost two lines, six gained ≥2 lines
Mean astigmatism ↓ from -2.60D pre-op to -1.05D at 1 year
5/22 using refractive correction at 1 year with symptom improvement in 19/22
Complications: 3 delayed epithelial healing beyond one week, 1 herpetic keratitis = all 4 recovered pre-op BSCVA

13. Complications: HSV keratitis
20yr old male
RGP intolerant, KC OS>>OD
Pre-op, OS: x075 20/30
10 day post-op: remove BCL, photophobia, dendrite – Valvocyclovir, Trifluridine
18mth post-op: UVA 20/30
OS: -0.25/-1.25x115 20/25-

14. Bevan, Tyler-TGPRK/CXL, HSV

15. Conclusions: Simultaneous Topography-guided PRK with CXL
Satisfactory early results were achieved with simultaneous TG-PRK (Custom TNT) with CXL
Degree of refractive correction limited by corneal thickness although 70% were able to gain 20/40 or better UCVA at 12 months
Simultaneous TG-PRK (Custom TNT) with CXL is a novel technique with the ability to improve both UCVA and BCVA in keratoconus

16. Thank-you