Iontophoretic treatment of experimental pseudomonas keratitis in rabbit eyes using gentamicin-loaded hydrogels

PURPOSE: To evaluate the efficacy of iontophoresis using a hydrogel probe containing gentamicin for the treatment of Pseudomonas keratitis in the rabbit cornea. METHODS: Five groups (Groups 1-5) of 8 rabbits each were infected by injecting Pseudomonas aeruginosa into their corneas. Three dosings of corneal iontophoresis were performed, at intervals of 3.5 hours, using soft disposable gentamicin-loaded hydroxyethyl methacrylate hydrogel discs mounted on a portable iontophoretic device. Groups 1 and 2 were treated with corneal iontophoresis for 60 seconds and a current of 0.5 and 0.2 mA. Groups 3 and 4 were treated with hydrogel loaded with 0.9% NaCl solution, using a current of 0.2 mA and mock iontophoresis. Group 5 was treated with eye drops of 1.4% gentamicin every hour for 8 hours. One and a half hours after the last treatment, the animals were killed, and the corneas were excised and cultured for P. aeruginosa count after 24-hour incubation. RESULTS: After iontophoretic treatment of gentamicin with a current of 0.5 mA (Group 1), the logarithmic value of Pseudomonas colony-forming units (CFUs) was 2.96 ± 0.45. After lower current iontophoretic treatment (Group 2), the logarithmic Pseudomonas count was 5.25 ± 0.54 CFUs. At the control groups (Groups 3-5), the Pseudomonas counts were found to be much higher, 7.62 ± 0.28, 7.22 ± 0.29, and 6.29 ± 0.45 CFUs, respectively. CONCLUSION: A short iontophoretic treatment using gentamicin-loaded hydrogels has potential clinical value in treating corneal infections.