Implantation of a triamcinolone acetonide drug delivery system into the suprachoroidal space for the prevention of traumatic anterior proliferative vitreoretinopathy

Background: Anterior proliferative vitreoretinopathy (aPVR) is a tissue injury and repair progress, and treatment of aPVR is very important in clinic. Chitosan drug delivery system is becoming a hot spot for its large lading dose and long acting duration. Objective: The present study was to investigate the curative effect of a triamcinolone acetonide (TA) drug delivery system after implantation into the suprachoroidal space to treat traumatic aPVR. Methods: aPVR models were created in the left eyes of 65 healthy pigment rabbits by performing a 5 mm penetrating incision 2.5 mm posterior to limbum at 10: 30-11: 30. The animals were randomly divided into 4 groups. Blank chitosan was implanted into the suprachoroidal space as the blank control group. Chitosan with 1 mg TA was implanted in the TA + chitosa group. The TA solution (containing 1 mg TA) was intravitreally injected in the TA injection group. Fifteen models were used as the traumatic control group. Another 15 left eyes of normal pigment rabbits were used as the normal control group. The thickness of the ciliary tissue was measured using a ultrasound biomicroscope(UBM) 3, 5 and 8 weeks after operation. The animals were sacrificed by excessive anesthesia and eyeballs were obtained for histopathological and ultrastructural examinations. Results: Histopathological examination showed the edema of the ciliary tissue and inflammatory cells infiltration in the blank control group, TA injection group and model control group, but mild response was seen in the TA + chitosa group. Severe damage in the ciliary tissue and subcellular organelle was found in the blank and model control groups, but mild damage was detected in the TA + chitosa group under the transmission electron microscope. UBM examination revealed that obvious abnormalities were visible in the ciliary and iris tissue in the blank control group, TA injection group and traumatic control group, but a mild abnormality was seen in the TA + chitosa group. Significant differences in ciliary thickness were exhibited among the 5 groups 2, 5 and 8 weeks after operation (F=212.938, 515.323, 447.919, P<0.01). Compared with the normal control group, ciliary thickness significantly increased in the blank control group and normal control group at various time points (all P<0.05), but that in the TA + chitosa group was significantly lower than the normal control group at various time points (two weeks: 0.484±0.075 vs. 0.327±0.094; five weeks: 0.422±0.089 vs. 0.327±0.094; eight weeks: 0.418±0.085 vs. 0.327±0.094) (all P>0.05). Conclusions: The chitosan drug delivery system with TA suppresses the excessive proliferation of injured ocular tissue after implantation into the suprachoroidal space, which prevents the formation and development of aPVR.