Retinal vein cannulation with prolonged infuion of tiue plaminogen activator (t-PA) for the treatment of experimental retinal vein occluion in dog

Purpoe To evaluate the feaibility, afety, and efficacy of local thrombolytic agent directly injected into occluded retinal vein in an experimental animal model. Deign Experimental animal tudy. Method Thi experimental tudy wa performed in two phae. In phae 1, 15 enucleated porcine eye and 8 in vivo canine eye were ued for the development of the intrumentation and urgical technique required for retinal vein cannulation with prolonged intravacular infuion. In phae 2 of thi tudy, experimental branch retinal vein occluion wa photo-chemically created uing an intravenou injection of roe bengal followed by diode laer photocoagulation in eight eye of eight dog. Four eye were treated by retinal vein cannulation and an injection of tiue plaminogen activator (t-PA) uing a pecifically deigned microcatheter, while the remaining four eye were untreated (control group). The total amount of t-PA injected intravenouly ranged from 400 to 1000 μg, infued over a period ranging from 25 to 45 minute with a mean preure of 40 pi, reulting in a mean injection flow rate of 0.05 ml/min. The dog underwent clinical examination, fluorecein angiography, and hitologic examination. Main outcome meaure were: Achievement of prolonged intravacular infuion of t-PA, change in fundu appearance, fluorecein angiography, and hitology. Reult A microcatheter intrument and a urgical technique for retinal vein cannulation with prolonged intravacular infuion were developed. Cannulation and t-PA infuion for a period of at leat 30 minute wa achieved in all four treated eye with experimental branch retinal vein occluion. No complication were recorded in all treated eye. One week and 1 month potoperatively, treated eye exhibited marked decreae in retinal hemorrhage, retinal vein dilation, and tortuoity, wherea nontreated eye exhibited peritence of thee finding. Fluorecein angiography demontrated improved circulatory flow in treated relative to nontreated eye. Hitologic analyi confirmed the preence of thrombi in nontreated eye only. Concluion Retinal vein cannulation with prolonged intravacular injection of t-PA i feaible and afe, and thi may offer a new treatment option for retinal vein occluion.