Efficiency of Coulomb Controlled Iontophoresis for Transcorneal Delivery of Riboflavin: A pilot study

Abstract

 

Purpose:

 

To quantify transcorneal delivery of riboflavin using coulomb controlled iontophoresis (CCI) by measuring riboflavin concentration in the aqueous.

 

Methods:

 

Nine New Zealand white rabbits (17 eyes) were included in this study. The experiments were divided into five distinct groups: 1. Control (no riboflavin delivery); 2. CCI without current, epithelium intact; 3. CCI with 5mA/cm² current density, epithelium intact; 4. CCI without current, epithelium removed; 5. CCI with 5mA/cm² current density, epithelium removed. Riboflavin solution (10mg riboflavin-5-phosphate in 10mL Dextran 20% solution) was placed in the transcorneal CCI applicator and delivered to the eye for five minutes. After riboflavin delivery, the cornea was irradiated for 30 minutes using UVA radiation at 378nm with an irradiance of 3mW/cm². To maintain hydration during irradiation, one drop of riboflavin solution was placed on the cornea every 5 minutes. The aqueous humor was then collected from all eyes and stored at -20°C. Riboflavin concentration was measured using its natural fluorescent properties. A wavelength of 450nm is used for excitation and the absorption was measured between 520-650nm.

 

Results:

 

The riboflavin concentrations in the aqueous for groups 1-5 are shown in the table. The CCI with current and with the epithelium removed was the most efficient at delivering riboflavin, although riboflavin is delivered through the cornea even with an intact epithelium.

 

Conclusions:

 

CCI is effective at delivering riboflavin to the cornea. These results suggest that CCI is an alternative methodology for riboflavin delivery for cornea crosslinking. Support: CromaPharma; AlchimiA SRL; NIH IMSD (JD); NIH center grant P30-EY014801; Research to Prevent Blindness; Henri and Flore Lesieur Foundation (JMP)  

 

Keywords: keratoconus • cornea: clinical science • anterior segment