Corneal Stiffening Follows Accelerated Crosslinking Despite Initial Thinning

Biomechanical and tomographic assessments can reveal corneal stiffening and thinning effects following accelerated corneal crosslinking.

The accelerated corneal crosslinking (CXL) procedure may alter biomechanical parameters and reveal a corneal stiffening effect in individuals undergoing treatment for progressive keratoconus (KC), according to research published in Cornea. Despite this stiffening, corneal thinning occurred and was most significant at the 1-month follow-up visit, according to the report. 

Researchers enrolled 43 individuals with progressive KC (eyes, 43) and included untreated fellow eyes (n=25) as controls in an investigation conducted at a single center between November 2017 and December 2019.  Participants underwent biomechanical assessment using Scheimpflug-based tonometry and tomographic measurements at baseline and during 1-, 6-, and 12-month follow-up visits. The team compared biomechanical parameter alterations between treated and untreated eyes. 

Central corneal flattening occurred following accelerated CXL, evidenced by a 1.1 diopter (D; 95% CI, -2 to -1; P =.025) maximum keratometry (Kmax) decrease at 12 months compared with baseline. Thinnest corneal thickness values revealed significant corneal thinning at the 1-month postoperative visit compared with baseline (449 vs 463 µm; P <.001), but these values recovered to preprocedural levels at 12 months (P =.752). Biomechanically-corrected intraocular pressure (bIOP) increased (14.8 vs 13.3; P =.002), the time to second applanation shortened (22.06 vs 22.27 m/s; P =.024), and integrated radius values were lower at the 1-month follow-up compared with baseline. The eyes used in the control analysis did not experience any significant changes in biomechanical or tomographic parameters, the report shows. 

[A] higher severity of KC seems to benefit from a higher cross-linking effect.

“[T]he alterations in biomechanical parameters indicated a corneal stiffening effect after CXL treatment, which was best detectable 1 month after treatment, although [central thickness] was reduced,” according to the researchers. “However, a higher severity of KC seems to benefit from a higher cross-linking effect.”

Study limitations include a single center design and failure to assess non accelerated CXL protocols.


Herber R, Francis M, Spoerl E, Pillunat LE, Raiskup F, Roy AS. Evaluation of biomechanical changes after accelerated cross-linking in progressive keratoconus: a prospective follow-up study. Cornea. Published online January 20, 2023. doi:10.1097/ICO.0000000000003219