ABSTRACT
AIM: To investigate the safety of tissue plasminogen activator (tPA) intra optic nerve injection in rabbits. METHODS: Group 1 and 2 (6 eyes in each group) received injection of tPA 25μg and 12.5μg in 0.1mL balanced saline solution (BSS). Group 3 (6 eyes) received injection of 0 1mL BSS. Six eyes in group four as a normal control received no injection. The eyes were examined with slit lamp biomicroscope, indirect ophthalmoscope, visual evoked potentials (VEP) and electroretinography (ERG) at 1, 3, 7, 14 and 28 days after injection. RESULTS: No evidence of optic nerve or retinal toxicity or physical damage were revealed by ophthalmoscopy, VEP, and ERGs after the injection of tPA into the optic nerve. The means of the latency of the first peak of the VEP were 24.6±1.5, 24.1±1.9, 24.0±2.0 and 24.6±1.3mS respectively for the above specified groups (P=0.4112). The means of the amplitude of the first peak of the VEPs were 124±42, 145±41, 132±48 and 117±29μV respectively (P=0.0649). The means of the latency of a-waves were 6.0±0.4, 5.9±0.4, 5.9±0.5 and 5.8±0.3 mS respectively (P=0.6279). The means of the amplitude of a-waves were 110±14, 112±15, 110±16 and 108±11μV respectively (P=0.7248). The means of the amplitude of b-waves were 151±12, 148±14, 144±16 and 141±20μV respectively (P =0.0957).CONCLUSION: Injection of tPA upto 25μg in 0.1mL into optic nerve is well tolerated.
ABSTRACT
AIM: To investigate the feasibility and efficacy of tissue plasminogen activator (tPA) injection into the optic nerve as a treatment for retinal vein occlusion in rabbits. METHODS: Rose Bengal-mediated laser-induced retinal vein occlusions were produced in rabbit eyes. Fluorescein angiography (FA) was performed on each eye 3 days before laser irradiation and 30 minutes after laser irradiation.The treatment group (n=20 veins) received intra-optic nerve injection of tPA (12.5μg in 0.05mL BSS) and the controls (n=24 veins) received 0.05mL BSS. FA was repeated to determine the recanalization of the vessel at 3 and 7 days after treatment, followed by histological examination.RESULTS: Rose Bengal-mediated laser-induced retinal vein occlusions were successfully developed and confirmed by FA. The incidence of the recanalization of the vessels in treatment animals was 70.0%, while 16.7% in the control animals (P=0.001). CONCLUSION: Intra-optic nerve tPA injection increased the incidence of recanalization of the occluded vessels. Although further studies are needed, our data suggested that injection of tPA into the optic nerve may have a potential benefit in the treatment of central retinal vein occlusion.