Characteristics influencing outcomes of corneal collagen crosslinking for keratoconus and ectasia: Implications for patient selection

PurposeTo determine preoperative patient characteristics that may predict topography and visual acuity outcomes of corneal collagen crosslinking (CXL).SettingCornea and refractive surgery practice.DesignCohort study.MethodsCrosslinking was performed in eyes with keratoconus or corneal ectasia. Multiple regression and odds ratio analyses were performed to determine independent predictors of changes in topography-derived maximum keratometry (K) and corrected distance visual acuity (CDVA) 1 year postoperatively. Preoperative characteristics included sex, age, uncorrected distance visual acuity (UDVA), CDVA, maximum keratometry (K), corneal thickness, corneal haze, disease group, and cone location. Postoperative improvement in maximum K was defined as flattening of 2.0 diopters (D) or more and worsening as steepening of 1.0 D or more. Improvement in CDVA was defined as a gain of 2 lines or more and worsening as a loss of 1 line or more.ResultsThe study comprised 104 eyes (66 keratoconus; 38 corneal ectasia). Eyes with a preoperative CDVA of 20/40 or worse were 5.9 times (95% confidence interval [CI], 2.2-6.4) more likely to improve 2 Snellen lines or more. Eyes with a maximum K of 55.0 D or more were 5.4 times (95% CI, 2.1-14.0) more likely to have topographic flattening of 2.0 D or more. No preoperative characteristics significantly predicted worsening of visual acuity or corneal topography.ConclusionsPatients with worse preoperative CDVA and higher K values, particularly with a CDVA of 20/40 or worse or a maximum K of 55.0 D or more, were most likely to have improvement after CXL. No preoperative characteristics were predictive of CXL failure.Financial DisclosureDr. Hersh is a medical monitor for Avedro, Inc. Dr. Greenstein has no financial or proprietary interest in any material or method mentioned.