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Giuseppe Lombardo, Valentina Villari, Norberto Liborio Micali, Nancy Leone, Marco Lombardo; Non invasive label free hyperspectral method to assess corneal cross-linking efficacy. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2893. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
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.
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.
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).
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.
During corneal cross-linking, the corneal tissue is imaged by a RGB camera. The hyperspectral response of the cornea is evaluated in a region of interest (green circle) in order to assess the stromal riboflavin concentration and the induced stiffness.
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