Purpose:
To investigate clinical outcomes two years after corneal collagen crosslinking (CXL) for keratoconus (KC) and ectasia.
Methods:
50 eyes (38 patients) underwent CXL for keratoconus (n=34) or ectasia (n= 16) in a prospective, randomized controlled trial. CXL was performed with a UVX system (Peschke Meditrade GmbH) using standard technique. Clinical outcomes including uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), maximum keratometry (Kmax), CXL associated corneal haze, and corneal thickness were assessed and analyzed at baseline, 1 month, 3 month, 6 month, 1 year, and 2 year follow up visits. Corneal haze was measured by Scheimpflug densitometry.
Results:
In the entire cohort, mean UCVA preoperatively was 20/151 (logMAR 0.88±0.35) and improved at 2 years to 20/136 (logMAR 0.83±0.38, p=0.2). BCVA was significantly improved from 20/46 (logMAR 0.36±0.24) to 20/35 (logMAR 0.24±0.19) (p<0.001). On topography, Kmax flattened significantly by 2.0±4.7D (p=0.004). Pachymetry values at 2 years were not significantly different from baseline (p=0.3). Corneal haze remained slightly increased at 2 years compared to baseline (+1.33±3.8, p=0.02). Between 1 and 2 years, the change in UCVA (change=-0.02±0.30, p=0.7), BCVA (change=-0.04±0.16, p=0.08), and Kmax (change=-0.05±2.9D, p=0.9) were not statistically significant. Mean corneal haze (change=-1.17±4.7), and pachymetry (change=+3.4±21.8µm), both continued to return toward baseline measurements, but these changes failed to reach statistical significance as well (phaze=0.09, ppachymetry=0.3). A similar clinical course was found in the analysis of stratified KC and ectasia subgroups.
Conclusions:
At 2 years, CXL was effective at improving visual acuity and topographic outcomes. Clinical outcomes remained stable between 1 and 2 years after CXL.
Clinical Trial:
http://www.clinicaltrials.gov NCT 00647699
Keywords: keratoconus • refractive surgery: other technologies • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials