In Vivo Ultrasound-enhanced Penetration Of Topical Riboflavin Into The Corneal Stroma

Abstract

Purpose: To determine whether ultrasound treatment can promote the permeation of topical riboflavin into the corneal stroma in vivo.

Methods: New Zealand white rabbits were used for the study. Treated eyes had a cup with riboflavin 0.1% placed over the central cornea and were treated with ultrasound 1 W/cm2 at 880 Khz for 6 minutes followed by the removal of the cup and the application of two drops of riboflavin solution every 3 minutes for 39 minutes. In the control eyes (no ultrasound) two drops of riboflavin solution were applied every 3 minutes for 45 minutes. Animals were then sacrificed, corneas were excised, and confocal microscopy was performed to detect the presence of riboflavin in the cornea.

Results: Fluorescence intensity was significantly higher in the treated corneas (P<0.05). At a depth of 200 microns, average fluorescence intensity of riboflavin was 216.24 in treated eyes (n = 7), and 6.55 in control eyes (n=6).

Conclusions: Ultrasound treatment facilitated the entry of topical riboflavin into the corneal stroma. This approach may offer a means of achieving clinically useful concentrations of riboflavin in the cornea without removing the corneal epithelium, thereby improving the risk profile of corneal cross-linking procedures.

Keywords: 574 keratoconus • 480 cornea: basic science