Transscleral iontophoresis as an adjunctive treatment for experimental endophthalmitis

We examined the efficacy of transcleral iontophoresis as an adjunct to intravitreal injection in the treatment of experimental Pseudomonas endophthalmitis in rabbits. Animals received no antibacterial treatment (untreated controls; group 1), a single intravitreal injection of 100 micrograms of gentamicin sulfate (group 2), or the same dose of gentamicin sulfate along with two treatments of transscleral iontophoresis given 24 and 48 hours after the intravitreal injection (group 3). Treatment was initiated 16, 24, or 48 hours after the induction of infection. For each interval from infection to treatment, there was a lower bacterial count and a higher rate of sterilization in the eyes in group 3 than in group 2; both treated groups had better outcomes than the untreated controls. These data suggest that transscleral iontophoresis could be clinically useful as a supplement to intravitreal injection for a refractory type of endophthalmitis such as that caused by Pseudomonas aeruginosa.