| Objective:To research the effect of various posterior vitreous detachment(PVD)induced by plasmin alone or combined with hyaluronidase on proliferative vitreoretinopathy(PVR).Methods:twenty-four pigmented rabbits were randomly divided into two experimental groups (group A and B)and one control group,PVR was induced in pigmented rabbits by intravitreal injection of platelet rich plasma.At the meantime,the eyes in group A and B received an intravireal injection of(1U plasmin +20U hyaluronidase)0.1ml,1U plasmin 0.1ml respectively, and equivalent dose of balanced salt solution was intravitreally injected to the control group.The eyes were examined ophthalmoscopically on distinct days after the intravitreal injection,and the stage of PVR was evaluated.Results:(1)Stage of PVR:observation by ophthalmoscope showed that except on 28d after intravitreal injection,PVR stage of group A(give a mark 7/6)and B(give a mark 15/6)were both lower than that of the control group(give a mark 23/6)(P=0.003,P=0.011),there were no significant differences among groups on other days(3d,7d after injection).(2)Flash-Electroretinogram(F-ERG)recordings:repeated measurement data showed that the b-wave amplitude on ld before and after injection in group A,B and the control group have no statistical difference(P=0.941 and P=0.965).On 7d and 28 d after injection,the b-wave amplitude in group A and B was significantly higher than that in the control group(P＜0.05and P＜0.05).(3)B-scan ultrasound observation:all eyes in every group were heathy and spontaneous PVD was not observed before injection.On 7d after injection,complete PVD was found in 5 eyes(5/8) and partial PVD in 3 eyes(3/8)in group A;partial PVD in 5 eyes(5/8)and no complete PVD in group B;there was no PVD in the eyes of the control group however.Among the eyes in which PVD happened,most vitreouses were clear and a few slightly turbid(PVR class 0-1).Vitreouses were turbid obviously in the eyes which PVD did not happen,and membranes before retina occurred in some ones(PVR class 1-2).On 28d after injection,Vitreouses were turbid in the complete PVD eyes;retinas became thicker and were pulled in part(PVR class 2)in the partial PVD eyes;varying degree retina detachment(PVR class 3-5)happened in the no-PVD eyes.(4)Histopathologic observation:retinas were nearly normal in complete PVD eyes both on 7d and 28d after injection;retinas became thicker in part on 7d in partial PVD eyes and were pulled and distorted on 28d;proliferative membranes before retinas were thick while retinas were distorted seriously and crapy in no-PVD eyes on 7d,and more proliferative membranes turned up with retinas' structure disorganized on 28d.Observation by transmissing electronmicoscope:retinas of complete PVD eyes were normal with regular arrangement of outer and inner segment and mitochondrias were not obviously swollen.Some mitochondrias were swollen lightly but inner and outer segment membrane disks were arranged regularly in partial PVD eyes on 7d;mitochondrias had obvious edema and outer segment membrane disks were not regularly on 28d.Some fibers could be seen in the fiber layer in no-PVD eyes on 7d,Conclusions:(1)In the early stage of proliferative vitreoretinopathy of rabbit eyes,complete or partial PVD could be induced by intravitreal injection of 1U plasmin combined with 20U hyaluronidase in experimental eyes while partial PVD could only be induced in part of experimental eyes by 1U plasmin alone.(2)Complete PVD induced by medicine could prevent the development of proliferative vitreoretinopathy of rabbit eyes in some degree;partial PVD could lighten the development of proliferative vitreoretinopathy. |
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