PURPOSE: To evaluate biomechanical changes induced by epithelium-off corneal cross-linking (CXL) in progressive keratoconus using Brillouin microscopy (BOSS; Intelon Optics) and ultra-high-speed Scheimpflug camera (Corvis ST; Oculus Optikgeräte GmbH).

METHODS: Twenty-three eyes from 24 patients were included in this retrospective, multicenter study. Biomechanical properties were assessed before and 1 month after CXL using the BOSS and Corvis ST. Brillouin measurements included mean, minimum, and maximum Brillouin frequency shift (BFS) and sectors (inferior, equator, and superior). The Corvis ST assessed dynamic corneal response (DCR) parameters, including inverse concave radius (1/R) and stress-strain index (SSI). Statistical analyses included Wilcoxon tests, Pearson correlation, and linear mixed models, with adjustments for corneal pachymetry.

RESULTS: Brillouin microscopy demonstrated significant stiffening after CXL, with increases in mean BFS and maximum BFS, together with inferior and equatorial regions (P < .001). A strong correlation was observed between preoperative BFS and postoperative changes (R2 = 0.597, P < .001). The Corvis ST confirmed biomechanical stiffening with a significant decrease in 1/R values (P = .002), although no significant changes were observed in SSI.

CONCLUSIONS: Both Brillouin microscopy and the Corvis ST effectively detected corneal stiffening after CXL, with Brillouin technology offering localized biomechanical insights. These findings highlight the potential of Brillouin microscopy for guiding customized CXL treatments and underscore its complementary role alongside the Corvis ST. [J Refract Surg. 2025;41(6):e594-e601.].