Electroporation and bleomycin in glaucoma-filtering surgery

Purpose. To develop a new treatment in glaucoma-filtering surgery using combined treatment with electroporation and the antiproliferative drug bleomycin. Methods. Pigmented rabbits were treated with both bleomycin (10 μg/ml) and localized electric pulses (EP) using a special probe (5 V/cm, 100 msec, 8 pulses) (n = 10; group A). After EP treatment, bleomycin was washed out with 50 ml balanced salt solution, and then a posterior lip sclerectomy was performed on the same area. We also studied rabbits undergoing a posterior lip sclerectomy with bleomycin treatment alone (n = 10; group B), a posterior lip sclerectomy with EP treatment alone (n = 5; group C) and a posterior lip sclerectomy alone using the same operation (n = 5; group D, negative control). The intraocular pressure (IOP) was measured before and 1, 3, 5, 7, 10, 15, and 20 days after surgery. The formation of blebs, the conjunctiva, and the cornea were periodically examined by slit-lamp biomicrography. Results. In every group, the lOP decreased until day 7, and no significant difference was observed among the four groups. In groups B, C, and D (control), the IOP increased gradually from day 10 and thereafter returned to the preoperative level after 15 days. However, in group A, the IOP remained lower than the preoperative level for 20 days; it was also significantly lower than each of the other three groups (P< 0.01). The survival rate of a filtering bleb was significantly higher in group A than in groups B, C, or D, but the survival rate in group B was not higher than groups C or D. No adverse effects were clinically observed in the ocular tissue, such as the cornea and conjunctiva. Conclusions. The combined treatment with EP and bleomycin was found to decrease IOP more prominently than EP or bleomycin treatment alone in filtering surgery. This treatment thus makes filtering surgery effective by decreasing the dose of the antiproliferative drug and by possibly localizing the drug delivery.