Forward-Looking and Multicentric Study of Ocular Pharmacokinetics of Riboflavin in Vivo During a Procedure of Corneal Collagen Cross-Linking : 25 Cases Report

Abstract

Purpose: : Corneal collagen cross linking in evolutive keratoconus is a photochemical reaction which catalyzes a biochemical reaction. For the first time, we offer its study and we bring it to light by measuring riboflavin fluorescence in vivo through a 25 procedures serie carried out in Clermont-Ferrand University Hospital Center and Toulouse University Hospital Center.

Methods: : We present a 25 patients serie treated with collagen cross linking coupled with fluorescence analysis. This test is carried out with master FM-2 Fluorotron, usually used for flurescein study. We calculated the correction factor to adjust our device to the riboflavin study. Thus we have been able through this procedure to study the ocular pharmacokinetics of riboflavin (Ricrolin®).

Results: : The study of corneal fluorescence variation in anterior chamber and lens before, while and after the procedure allows us to confirm each step of the chain reaction for the first time in an in vivo study. Then we can detect the corneal impregnation of riboflavin ( with concentration measurement in ng/mL) and its intracameral path. Moreover, we can show the riboflavin screen effect on UVA and its reduction under UVA . Finally, the hypothesis of links created between collagen strands, then unverified in vivo, can be emphasized through our study.

Conclusions: : As the first study of riboflavin pharmacokinetics in vivo during corneal collagen cross linking, this study can confirm theoretical hypotheses and objectify the treatment efficiency in the same way. Fluorescence study allows to measure low concentration with excellent reliability. Collagen cross linking coupled with fluorometry could help to estimate cross linking immediate efficiency and to change its practice.

Keywords: keratoconus • cornea: storage • microscopy: light/fluorescence/immunohistochemistry