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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
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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
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
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
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-
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