Abstract
Purpose :
To present a novel, non invasive, optical method for assessing the concentration of stromal riboflavin in riboflavin/UV-A corneal cross-linking in order to determine treatment efficacy.
Methods :
Eight human donor corneas were de-epithelialized and soaked with 20% dextran-enriched 0.1% riboflavin. Four tissues were then irradiated using 3 mW/cm2 UV-A device for 30 minutes and the other four using 10 mW/cm2 UV-A device for 9 minutes. During treatment, corneal specimens were imaged using a novel optical method in order to collect their hyperspectral response in real time. A calibrated RGB camera recorded the fluorescence and the diffuse reflectance images from each tissue and a processor elaborated the information in order to evaluate the stromal riboflavin concentration both during stromal soaking and UV-A irradiation of the cornea. Immediately after treatment, the elastic modulus of the anterior stroma in each specimen was probed by means of atomic force microscopy.
Results :
After stromal soaking, the concentration of riboflavin in the stroma showed consistent results between tissues (0.016% ± 0.003%). During UV-A irradiation, the stromal riboflavin concentration decreased non linearly over time, then reaching the minimum value of 0.006% ± 0.002% at the end of treatment. A regression model was developed to correlate the stromal riboflavin consumption with the increase of corneal stiffness. The results of the model were highly significant (R = 0.79; P = 0.03).
Conclusions :
The present label-free optical method shows to be reliable for the assessment of stromal riboflavin concentration during corneal cross-linking. The method is an active monitoring solution of the stromal riboflavin consumption during corneal UV-A irradiation, which provides an estimation of treatment efficacy in real-time.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.