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Observational Study
. 2025 Jul 1;25(1):378.
doi: 10.1186/s12886-025-04195-5.

Evaluation of refractive, tomographic and biomechanical changes after customized accelerated corneal collagen cross-linking in keratoconus patients: a retrospective observational study

Robert Edward T Ang  1   2 , Alvin Joseph A Guloy Jr  2 , Emerson M Cruz  3 , Jimmy Jarvis Gene C Lo  1
Affiliations
Observational Study

Evaluation of refractive, tomographic and biomechanical changes after customized accelerated corneal collagen cross-linking in keratoconus patients: a retrospective observational study

Robert Edward T Ang et al. BMC Ophthalmol. .

Abstract

Objective: To evaluate the refractive, keratometric, and biomechanical changes in keratoconus patients following modified accelerated corneal cross-linking (A-CXL).

Methods: This retrospective observational study analyzed clinical data from patients with progressive keratoconus who underwent modified A-CXL with a prolonged riboflavin imbibition period prior to UV irradiation. Preoperative and post-operative data on vision, refraction, tomography using OCULUS Pentacam and biomechanics using Corvis ST were analyzed at various follow-up intervals. Subgroup analysis was conducted based on topographic keratoconus classification. Statistical comparison was performed to assess changes in these parameters over time.

Results: A total of 70 eyes of 55 patients were included. A statistically significant improvement in mean change of logMAR BCVA was noted at 6 and 12 months (p = 0.006 and p = 0.018). Six months following A-CXL, statistically significant improvements were observed in keratometry and pachymetry (p = 0.003 and p < 0.001). Mean changes in biomechanical parameters deformation amplitude ratio (DAR) and Integrated Radius (IR) were found to be significantly decreased at 6 months (p = 0.001 and p = 0.011). Other biomechanical parameters SPA1, SSI and ARTh had no significant changes suggesting stability. Comparative analysis between different stages of keratoconus revealed that patients classified under TKC-4 exhibited greater improvement in keratometry compared to those with TKC-2 and TKC-3 staging.

Conclusion: A-CXL with extended riboflavin exposure was effective in stabilizing both tomographic and biomechanical parameters which resulted in increased corneal stiffness and maintained stability. All KC stages demonstrated corneal stability following A-CXL.

Keywords: Accelerated corneal collagen cross linking; Corneal biomechanics; Keratoconus; Keratometry; Refractive changes.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: In compliance with institutional guidelines for research involving human subjects, the Cardinal Santos Medical Center Research Ethics Review Committee has officially approved the study protocol and waived the need to obtain participants'informed consent. The decision was made on the basis of the study's retrospective design, low participant risk, and use of anonymized data. The decision was made after a careful evaluation of the research protocol and ethical issues, with a strong emphasis on protecting participant rights and welfare. All procedures were carried out in complete conformity to ethical norms and guidelines. Consent for publication: Not Applicable. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Study Design Flowchart for Modified Accelerated Corneal Collagen Cross-Linking in Keratoconus Patients. This flowchart outlines the patient selection process, inclusion and exclusion criteria, preoperative assessment parameters, surgical procedure, follow-up schedule, and evaluated outcome measures in a retrospective study involving 70 patients undergoing modified A-CXL for progressive keratoconus. Outcome measures include changes in refractive error, corneal tomographic indices, and corneal biomechanical parameters over a 12-month period
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