Variation in central corneal thickness during open- or closed-eye riboflavin instillation for corneal collagen cross-linking.

Purpose: To assess the effect of having an open or closed eye on the variation in central corneal thickness during riboflavin instillation for corneal collagen cross-linking (CXL).

Methods: Thirty eyes of 15 New Zealand White rabbits underwent an in vivo anterior segment optical coherence tomography (OCT) examination at 0, 10, 20, and 30 min after riboflavin instillation on the de-epithelialized corneal surface. Each eye of every rabbit was randomly placed into one of two different treatment groups (open-eye or closed-eye) during the instillation; the examinations were performed one after the other. After instillation for 30 min, the changes in the corneal stroma and anterior chamber were observed by slit lamp.

Results: A significant decrease in the central corneal thickness (CCT) was demonstrated during riboflavin instillation; the variations were smaller in the measurements performed with the eye closed than with the eye open (81.36 +/- 15.13 microm and 129.20 +/- 12.05 microm respectively). Both methods turned the corneal stroma and anterior chamber yellow.

Conclusion: Keeping the eye closed during riboflavin instillation reduced the decrease in the CCT. The same yellow change in the corneal stroma and anterior chamber occurred, but the exposure time of the ocular surface was shorter. Therefore, keeping the eye closed was a more effective and safer method than keeping the eye open.