[Antiproliferative effect of sustained drug delivery system of all-trans retinoic acid implant into rabbit's vitreous cavity for treatment of proliferative vitreoretinopathy].
OBJECTIVE: To investigate the antiproliferative effect of different concentration of all-trans retinoic acid (atRA) in a drug delivery system (DDS) in an experimental proliferative vitreoretinopathy (PVR) model. METHODS: The PVR animal model was induced by central vitrectomy and homologous fibroblasts injected at the same time in pigmented rabbits. Fifty rabbits underwent the surgery. These rabbits were divided into 5 groups of 10 rabbits at random. Group A was the control group. In group B, C, and E, one DDS device was implanted into the vitreous cavity after the vitrectomy, each DDS contained atRA 420 microg, 650 microg and no drug, respectively. In group D, two DDS devices were placed into the vitreous cavity, the total atRA content was 1,070 microg (420 microg + 650 microg). Each group was observed for 8 weeks. The development and the severity of PVR were observed and recorded. The vitreous cavity fluid was aspirated each week for measurement of the concentration of the atRA, in order to estimate the relationship between PVR and concentration of atRA. After 8 weeks, the retinal toxicity was evaluated by histopathology. Statistical analyses were performed at the end of the experiment. RESULTS: Eight weeks after the operation, the incidence of PVR was lower in group C and group D, and there was a significantly statistical difference between these two groups and other groups. No intraocular toxicity was found by the histopathology examination. CONCLUSIONS: atRA DDS is a safe and convenient mode for intraocular administration. DDS containing 650 microg and 1,070 microg atRA can inhibit the cell proliferation in the vitreous cavity effectively after surgery. atRA at a lower concentration cannot eliminate the cell proliferation but may delay the occurrence of PVR.