To compare the relative 12-month corneal crosslinking (CXL) functional outcomes using standard protocol and accelerated protocols in patients with progressive keratoconus.
CXL was performed using 3 epithelium-off protocols: standard [3 mW/cm2 for 30 minutes, 5.4 J/cm2 (S3/30-CXL)], accelerated with equivalent total irradiance [9 mW/cm2 for 10 minutes, 5.4 J/cm2 (A9/10-CXL)], and accelerated with increased total irradiance [30 mW/cm2 for 4 minutes, 7.2 J/cm2 (A30/4-CXL)]. Efficacy measurements were evaluated 12 months after treatment with Scheimpflug imaging (Pentacam HR) and included change in maximum keratometry (K Max), corrected distance visual acuity (CDVA), other keratometric variables, pachymetry, keratoconus indices, astigmatism, asphericity, manifest refraction, and higher order aberrations.
Ninety-three eyes (67 patients) were evaluated: 35 eyes (26 patients) with S3/30-CXL, 29 eyes (19 patients) with A9/10-CXL, and 29 eyes (22 patients) with A30/4-CXL. Mean [INCREMENT]K Max was −1.53 ± 2.1 diopter (D) for S3/30-CXL, −0.71 ± 1.3 D for A9/10-CXL, and −0.70 ± 2.3 D for A30/4-CXL (P = 0.37). Mean [INCREMENT]CDVA(logMAR) was −0.18 ± 0.2 for S3/30-CXL, −0.13 ± 0.2 for A9/10-CXL, and −0.18 ± 0.2 for A30/4-CXL (P = 0.79). [INCREMENT]K Mean (r = −0.29 to −0.46), anterior asphericity (r = −0.34 to −0.40), and central keratoconus index (r = −0.18 to −0.38) best correlated with [INCREMENT]CDVA. S3/30-CXL had greater changes in index of surface variance, index of vertical asymmetry, keratoconus index, and regularization index compared to A9/10-CXL and A30/4-CXL. There were no other differences between protocols.
All 3 protocols showed improvements in K Max, CDVA, and other variables, with similar functional outcomes for each despite greater change in keratoconus indices after S3/30-CXL. Correlations between change in measured variables and CDVA were poor overall; however, K Mean, central keratoconus index, and anterior asphericity were better correlated with CDVA than K Max.
*Keck School of Medicine of USC, Los Angeles, CA;
†ELZA Institute, Dietikon, Zurich, Switzerland;
‡Baylor College of Medicine, Cullen Eye Institute, Houston, TX;
§Ocular Cell Biology Group, University of Zurich, Zurich, Switzerland;
¶Paulista School of Medicine, Federal University of Sao Paulo, Sao Paulo, Brazil;
‖University of Wenzhou, Wenzhou, China; and
**University of Southern California, Roski Eye Institute, Los Angeles, CA.
Correspondence: J. Bradley Randleman, MD, USC Roski Eye Institute, Keck School of Medicine of USC, 1450 San Pablo St., Los Angeles, CA, 90033 (e-mail: email@example.com).
Supported in part by unrestricted departmental grants to the USC Roski Eye Institute and Baylor College of Medicine from Research to Prevent Blindness (New York, NY).
F. Hafezi—Shareholder/investor for EMAGine AG (Zug, Switzerland), consultant for GroupAdvance Consulting GmbH (Zug, Switzerland), exclusive patent owner for PCT patent/application (corneal apparatus used for CXL and chromophore for CXL application), recipient of travel funds from Light for Sight Foundation (Zurich, Switzerland), directed research funds from Light for Sight Foundation (Zurich, Switzerland), Schwind eye-tech-solutions (Kleinostheim, Germany), Velux Foundation (Søborg, Denmark), Gelbert Foundation (Geneva, Switzerland), and in-kind financial contribution for research materials from Sooft Italia (Montegiorgio, Italy). N. L. Hafezi—Shareholder/investor for EMAGine AG (Zug, Switzerland), consultant for GroupAdvance Consulting GmbH (Zug, Switzerland), recipient of travel funds from Light for Sight Foundation (Zurich, Switzerland), directed research funds from Light for Sight Foundation (Zurich, Switzerland). The remaining authors have no funding or conflicts of interest to disclose.
Received July 17, 2018
Received in revised form December 05, 2018
Accepted December 08, 2018