The Experimental Study On Chondroitinase Combined With Plasmin Induce Posterior Vitreous Detachment

[Objective] To investigate the toxicity of chondroitinase ABC and plasmin, and evaluate their efficacy in the production of posterior vitreous detachment. [Method] 18 young Newsland rabbits were randomized into 3 groups, 6 rabbits in each group. Different enzymes were injected intravitreal in right eyes: group 1 received chondroitinase ABC 0.1U/0.1ml; group 2 received chondroitinase ABC 0.1U/0.05ml and plasmin (Roche) 0.5U/0.05ml; group 2 received chondroitinase ABC 0.1U/0.05ml and plasmin (Calbiochem) 1.0U/0.05ml, all left eye received intravitreal 0.9% NS 0.1ml as control.Slit-lamp biomicroscopy ,+78 diopter lens, Electroretinogrphy and ultrasonograph examination were performed at 2 hours, 1 day and 1 week after injection. 2 rabbits were killed after each examination and the eyes were enucleated. Light and Eletron microscopy were performed to study the vitreretinal interface.[Result] In group 2, 5 partly PVD were found at 2 hours after injection, 4 partly PVD were found at 1day, 1 partly PVD and 1 complete PVD were found at lweek in the right eyes; In group 3, 4 partly PVD were found at 2 hours, 3 partly PVD were found at lday, 1 partly PVD and 1 completely PVD were found at lweek in the right eyes. No PVD were found at any time in group 1 and the left eyes, a, b wave in ERG display irreversible decrease and severe toxicity to retina in histopathological examination in the right eyes of group 2., But no change were found in the other groups and the control eyes in ERG and histopathological examination. [Conclusion] 1. Posterior vitreous detachment can not induced by 0.1U chondroitinase ABC intravitreal alone in 1 week in rabbit eye. 2. Posterior vitreous detachment can induced by 0.1 U chondroitinase ABC combined with 0.5U or 1.0U plasmin in 1 week in rabbit eye, but the PVD is partly in 1 week. 3. 0.1U chondroitinase ABC combined with 0.5U plasmin (Roche) intravitreal injectioncould cause severe toxicity to retina and affect the visual acuity;and 0.1U chondroitinase ABC combined with 0.5U plasmin(Calbiochem) intravitreal injection is safe without any harm to retina.