Abstract
Purpose :
Current protocols do not quantify riboflavin concentration or cross-linking and typically require removal of the corneal epithelium. This study measures the concentration of stromal riboflavin in vacuum-assisted transepithelial corneal cross-linking using a novel UV-A theranostics device.
Methods :
Nine human donor corneoscleral tissues with intact epithelium underwent transepithelial corneal cross-linking using a vacuum-assisted device for delivering dextran-free, hypotonic, 0.1% riboflavin with enhancers, and irradiating the cornea at 12 mW/cm2 for 9 minutes. The drug delivery device was composed of a small chamber with a perforated contoured surface in contact with the epithelium and a vacuum pump to control chamber air pressure. Seven additional control human donor corneoscleral tissues were de-epithelialized and soaked with 20% dextran-enriched 0.1% riboflavin solution for 30 minutes and then irradiated with 10 mW/cm2 for 9 minutes and used as controls. In both cases, the UV-A device (Chromo4Vis) used was based on theranostics technology, which provided real time measurement of the intrastromal concentration of riboflavin during treatment and assisted the user to best tailor corneal cross-linking to each corneal tissue.
Results :
Successful transepithelial riboflavin deposition with the vacuum-mediated device was achieved in all corneas with an average stromal concentration of 0.009%±0.003% and a maximum of 0.017%. After transepithelial UV-A irradiation, the intrastromal concentration of riboflavin decreased to 0.002%±0.0006%. In the epithelium-off control tissues, the average riboflavin concentration was 0.016% ± 0.003% after soaking; it decreased to 0.004% ± 0.002% after UV-A irradiation of the corneal stroma. In all cases, the stromal riboflavin concentration decreased non-linearly during UV-A irradiation of the cornea.
Conclusions :
The novel UV-A theranostics device successfully quantified stromal riboflavin concentration and monitored the corneal cross-linking process in real time. The vacuum-assisted device demonstrated transepithelial riboflavin deposition at concentration levels comparable to the control tissues with epithelium removed.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.