Corneal cross-linking-induced stromal demarcation line

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Corneal Science

Background:

• Corneal collagen cross-linking (X-linking) using UVA/riboflavin is a novel treatment for progressive keratoconus.
• Current monitoring of X-linking effectiveness relies on indirect methods like corneal topography or confocal microscopy.
• Effective X-linking is limited to the anterior 300 micrometers of the stroma to prevent endothelial damage.

Purpose of the Study:

• To describe a novel biomicroscopically detectable corneal stromal demarcation line.
• To establish this demarcation line as a tool for monitoring X-linking treatment depth in keratoconus.

Main Methods:

• Performed UVA/riboflavin X-linking in 16 patients with progressive keratoconus.
• Examined corneas using biomicroscopy, corneal topography, and pachymetry pre- and post-treatment.

Main Results:

• A distinct stromal demarcation line was observed in 14 out of 16 cases post-X-linking.
• This line appeared at approximately 300 micrometers depth, indicating the boundary of cross-linked stroma.
• The demarcation line was consistently visible via slit-lamp examination within 2 weeks.

Conclusions:

• The stromal demarcation line signifies the transition between treated and untreated corneal stroma.
• This finding offers an easily accessible method for biomicroscopically monitoring the depth of effective X-linking treatment.
• The line's appearance is attributed to changes in refractive index and reflection properties of the cross-linked stroma.