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Collagen cross-linking (CXL) alone vs CXL and simultaneous intracorneal ring segments vs CXL and simultaneous topography-guided photorefractive keratectomy in patients with keratoconus, pellucid marginal degeneration and LASIK-induced corneal ectasia

Poster Details

First Author: S.Ong Tone CANADA

Co Author(s):    N. Singal   S. El-Defrawy   W. Hatch              

Abstract Details


To compare the preoperative to one year postoperative changes in best-corrected spectacle visual acuity (BCSVA) and maximum keratometry (Kmax) in patients with progressive keratoconus, pellucid marginal degeneration (PMD) or Laser In Situ Keratomileusis (LASIK)-induced ectasia treated with CXL alone, CXL Simultaneous Intracorneal Ring Segments (ICR) or CXL Simultaneous Topography-Guided Photorefractive Keratectomy (TG-PRK).


This was a prospective single center cohort study completed at the Kensington Eye Institute.


We recruited subjects with mild to moderate keratoconus, PMD and LASIK-induced ectasia from June 2013 to March 2015. Two hundred and five eyes underwent CXL alone, 129 eyes underwent CXL․� and 119 eyes underwent CXL�PRK. All subjects underwent preoperative and postoperative assessments at 1, 3, 6, and 12 months that included BCSVA, corneal topography and tomography. A statistical model was constructed to analyze change, including a random effect to account for the correlation between eyes for subjects who had procedures performed on both eyes.


Preoperative mean BCSVA and Kmax for CXL, CXL․� and CXL�PRK were 0.359�Â�±0.146logMAR (20/46) and 58.25D�Â�±6.69D, 0.401�Â�±0.153logMAR (20/50) and 60.29D�Â�±5.72D, and 0.373�Â�±0.143logMAR (20/47) and 56.19D�Â�±4.98D, respectively. One-year postoperatively, mean BCSVA improved with CXL, CXL․� and CXL�PRK: 1.3, 2.3, and 1.7 lines, respectively. Magnitude of improvement in BCSVA was statistically significant: CXL․�>CXL by 0.102logMAR(p<0.0001), CXL�PRK>CXL by 0.047logMAR(p=0.041), CXL․�>CXL�PRK by 0.055logMAR(p=0.027). Mean Kmax flattening was 3.21D for CXL․�, 3.69D for CXL�PRK, and -0.08D for CXL. Magnitude of change in Kmax was statistically significant: CXL․�>CXL(p<0.0001), CXL�PRK>CXL(p<0.0001). No difference was found between CXL․� and CXL�PRK(p=0.5453).


One year after surgery, mean BCSVA had improved in all three groups. The greatest improvement was in the CXL․� group (1 line more than CXL alone). CXL�PRK improved more than CXL by about 2 letters and CXL․� improved more than CXL�PRK by almost 3 letters. Kmax flattened by over 3D in both the CXL-Intacs and CXL�PRK groups. CXL showed stabilization in Kmax as reflected in no change in Kmax at 1 year.

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