Correlation of Clinical and Biomechanical Outcomes of Accelerated Crosslinking (9 mW/cm 2 in 10 minutes) in Keratoconus with Molecular Expression of Ectasia-Related Genes.

PURPOSE: To assess visual, keratometry, densitometry, and corneal deformation outcomes after accelerated crosslinking (CXL) and its association with gene expression of extracellular matrix proteins.

METHODS: 33 eyes underwent accelerated CXL (9 mW/cm2 for 10 minutes) after epithelium removal. Refraction, visual acuity, keratometry, corneal densitometry, and deformation (Corvis-ST) were assessed before and 6 months after surgery. Epithelium-collected intraoperative was analyzed with qPCR to determine whether the molecular state of disease [lysyl oxidase (LOX), matrix metalloproteinase 9 (MMP 9), transforming growth factor beta (TGFβ), tumor necrosis factor-α (TNFα), interleukin 10 (IL10), interleukin (IL6), collagens (COL IA1 and COL IVA1)] had any bearing on the outcome.

RESULTS: Corrected distance visual acuity (CDVA) remained unchanged (p > 0.05). Cylinder (p = 0.0003) and spherical equivalent error (p = 0.02) reduced significantly after CXL. Keratometry and cone location magnitude index (CLMI) were unchanged after CXL (p > 0.05). Corneal densitometry was significantly altered only in the central 0-2 mm region (p = 0.009). A new measure of corneal deformation, named corneal stiffness, was also stable after CXL (p > 0.05). The preoperative level of different proteins did not influence the clinical outcomes described above (p > 0.05).

CONCLUSION: Accelerated CXL appears to be safe and provides biomechanical stability. Keratometry and refraction remained stable after CXL, with significant improvement in cylindrical error. Molecular expression profile of the keratoconic epithelium did not influence the clinical outcomes.