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

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: -1.25 or maximum correction of astigmatism if insufficient thickness Minimal predicted residual stromal depth 320microns

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/cm2 - 5.4 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.

TG PRK X-Linking for Keratoconus 20 year-old male 11 months post-op UCVA: 20/200 UCVA: 20/50 Pre-op: +4.00-4.00x075 Rx: -0.25-1.25x080 BCVA: 20/30 BCVA: 20/30 CT: 486 CT: 412 4 4

TG PRK X-Linking for Keratoconus 19 year-old male 9 months post-op Pre-op: -1.75-0.75x075 UCVA: 20/25 BSCVA: 20/30 Rx: -0.50-0.25x120 20/20 CT: 493 CT: 447 6 6

TG CXL PRK for KERATOCONUS Pre-op: +1.75-4.00x060 6 months post-op BSCVA: 20/30- UCVA: 20/30 RX: +0.25-0.75x170 20/25

TG CXL PRK for KERATOCONUS Pre-op: -2.75-2.25x010 12 months post-op BSCVA: 20/20- UCVA: 20/30- RX: +0.50-0.50x020 20/30-

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

Complications: HSV keratitis 20yr old male RGP intolerant, KC OS>>OD Pre-op, OS: +4.00-4.00x075 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-

Bevan, Tyler-TGPRK/CXL, HSV

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

Thank-you