Microscope-Integrated OCT-Assisted Real-time Monitoring of Central Corneal Thickness During Corneal Cross-linking.

Purpose: To assess real-time intraoperative pachymetry changes occurring during corneal cross-linking (CXL) using microscope-integrated optical coherence tomography (Mi-OCT) and compare accuracy of various modalities of pachymetry assessment.

Methods: This was a cross-sectional observational comparative study including 45 consecutive patients with progressive keratoconus planned for CXL. Mi-OCT (RESCAN 700) was used to measure central corneal thickness (CCT) during four stages of CXL: before epithelial debridement, after debridement, after riboflavin instillation, and after ultraviolet irradiation. Scheimpflug imaging, anterior segment OCT (AS-OCT), and ultrasound pachymetry were used to assess CCT preoperatively. All data were entered into Excel software (Microsoft Corporation) and analyzed.

Results: The CCT significantly decreased after each step of CXL as measured on Mi-OCT (P < .0001). Mi-OCT overestimated the CCT significantly by 1.12 times on average (range: 1.02 to 1.43) compared to ultrasound pachymetry (P = .0004). CCT measured using Scheimpflug imaging and anterior segment OCT was statistically comparable to ultrasound pachymetry.

Conclusions: Mi-OCT provides a real-time assessment of CCT during CXL. However, because it overestimates the pachymetry, ultrasound pachymetry remains the gold standard for decision-making during CXL. [J Refract Surg. 2024;40(12):e934-e940.].