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Ricardo Lamy, Peter D Jones, Manjiri Sahasrabudhe, Chris J Diederich, Jay M Stewart; Pulsed Low Frequency Ultrasound for Corneal Phonophoresis. Invest. Ophthalmol. Vis. Sci. 2021;62(8):1210.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose : To determine the effect of pulsed low frequency ultrasound (PLFU) at 250 kHz and 500 kHz on the delivery of topical compounds into the corneal stroma.
Fresh cadaveric rabbit eyes with intact corneal epithelium were placed in a solution of 0.1% riboflavin. Treated eyes received PLFU (60% duty cycle) with a Spatial Average Temporal Average Intensity (Isata) of 1.0 W/cm2 for 6 minutes at either 250 kHz or 500 kHz, and the eyes were then left in riboflavin solution for a total immersion time of 20 minutes. Control eyes without ultrasound treatment received the same exposure to riboflavin solution. Corneas were then excised, and confocal microscopy was performed to measure the penetration and distribution of riboflavin in the corneal stroma.
At a corneal depth of 300 microns, the average fluorescence intensity of riboflavin in the groups treated with PLFU 250 kHz and 500 kHz was respectively 9232 ± 2595 A.U. (n = 6) and 7454 ± 2184 A.U. (n=6). When compared to controls (1449 ± 690 A.U.; n=6) the difference was statistically significant for both treated groups (p-value < 0.05), demonstrating 5 - 6 fold therapeutic gain. The difference between corneas treated at 250 KHz and 500 KHz was not statistically significant.
PLFU was very effective in delivering riboflavin into the corneal stroma despite the presence of a previously intact epithelial barrier. This approach may offer a means of achieving clinically useful concentrations and penetration of topically applied drugs in the corneal stroma without removing the corneal epithelium.
This is a 2021 ARVO Annual Meeting abstract.
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