Riboflavin/ultraviolet a crosslinking of the paracentral cornea

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Corneal Science

Background:

• Corneal crosslinking (CXL) is a standard procedure for treating progressive keratoconus.
• The efficacy of CXL is dependent on achieving a specific stromal depth of treatment.
• Observed non-uniformity in CXL depth necessitates further investigation.

Purpose of the Study:

• To investigate the reduction in corneal crosslinking depth towards the periphery.
• To identify potential solutions for achieving homogeneous CXL depth across the cornea.

Main Methods:

• Standard CXL (epithelium-off, riboflavin, UVA) was performed on ten corneas.
• Optical coherence tomography (OCT) was used to measure demarcation line depth.
• Measured depths were analyzed as a function of radial distance from the corneal apex and compared to theoretical models.

Main Results:

• Corneal crosslinking depth significantly decreased towards the periphery, averaging 65% of central depth at 3 mm from the apex.
• The observed peripheral reduction in CXL depth was more pronounced than predicted by standard photopolymerization models.
• Current CXL protocols result in non-uniform treatment depth.

Conclusions:

• Intended corneal crosslinking depth is primarily achieved only in the central cornea with current technology.
• To ensure effective peripheral CXL, modifications to the ultraviolet beam's intensity profile or beam decentration are required.
• Further research is needed to optimize CXL delivery for comprehensive corneal treatment.