Two photon microscopic findings of sonoporation‐assisted enhancement of corneal penetration of fluoroquinolone antibiotics

PurposeTo investigate the sonoporation‐assisted enhancement of corneal penetration of fluoroquinolone antibiotics.MethodsEnucleated mouse corneas were imaged by two‐photon microscopy to observe normal corneal structure ex vivo. For estimation of the threshold of corneal epithelial damage, sonoporation was applied with different intensities (1.5, 2.0 and 3.0 W/cm2) for 5 minutes on each cornea. Gatifloxacin and besifloxacin were applied on each cornea and the depth of drug penetration was observed with two‐photon microscopy. After sonoporation (1.5 and 1.7 W/cm2, respectively) was applied with fluoroquinolone eyedrops, we compared the aspects of drug penetration in sonoporated cornea with those in normal cornea. In vivo two photon microscopy imaging was conducted with gatifloxacin application.ResultsNormal cornea observed with two‐photon microscopy showed regular arrangement of epithelial cells without any damaged cells. Threshold intensity of sonoporation that can damage some epithelial cells without significant structural destruction was determined as 1.5~2.0 W/cm2. When gatifloxacin was applied on normal cornea, gatifloxacin fluorescence was observed only on surface of corneal epithelium. After sonoporation, whole epithelium showed increased gatifloxacin and besifloxacin fluorescence. But the penetration depth and the extent of Besifloxacin were less than those of gatifloxacin, due to its own molecular structure. The threshold intensity was revealed as 1.3 W/cm2 in vivo. In vivo corneal penetration of gatifloxacin enhanced after sonoporation, and this result was comparable with that of ex vivo.ConclusionsWe observed the enhancement of corneal penetration of fluoroquinolone antibiotics after sonoporation was done on mouse cornea ex vivo as well as in vivo. Besifloxacin showed poor penetration compared with gatifloxacin even after sonoporation.