• Written By:
    Cornea/External Disease, Refractive Mgmt/Intervention

    This study compares 12-month functional outcomes of corneal crosslinking (CXL) using standard versus accelerated protocols in patients with progressive keratoconus.

    Study design

    The authors retrospectively evaluated findings from 3 epithelium-off methods of CXL for the treatment of progressive keratoconus. A total of 93 eyes (67 patients) underwent CXL, including 35 eyes treated with a standard method (3 mW/cm2 for 30 minutes, 5.4 J/cm2, known as S3/30-CXL); 29 eyes treated with an accelerated protocol using equivalent total irradiance (9 mW/cm2 for 10 minutes, 5.4 J/cm2, known as A9/10-CXL); and 29 eyes treated with an accelerated protocol using increased total irradiance (30 mW/cm2 for 4 minutes, 7.2 J/cm2, known as A30/4-CXL). Efficacy parameters were evaluated 12 months after treatment with Scheimpflug imaging (Pentacam HR), including changes in maximum keratometry (K Max), corrected distance visual acuity (CDVA), other keratometric variables, pachymetry, keratoconus indices, astigmatism, asphericity, manifest refraction and higher order aberrations.


    The average change in K Max was −1.53 D for the S3/30-CXL group, −0.71 D for the A9/10-CXL group and −0.70 D for the A30/4-CXL group (P=0.37). The mean change in CDVA was −0.18 logMAR for S3/30-CXL, −0.13 logMAR for A9/10-CXL and −0.18 logMAR for A30/4-CXL (P=0.79).

    The S3/30-CXL protocol produced greater changes in the index of surface variance, the index of vertical asymmetry, the keratoconus index and the regularization index compared with the A9/10-CXL and A30/4-CXL protocols. There were no other differences between protocols.


    This was a retrospective review. Though the study identified differences in certain keratoconus indices, the fact that these patients were only followed for 1 year may limit the ability to detect long-term differences in visual outcomes between populations with progressive disease.

    Clinical significance

    All 3 protocols showed improvements in K Max, CDVA and other variables, with similar functional outcomes for each method despite a greater improvement in keratoconus indices after S3/30-CXL. Correlations between changes in measured variables and CDVA were poor overall; however, K Mean, central keratoconus index and anterior asphericity were more highly correlated with CDVA than with K Max.