ABSTRACT
Background Dynamic observation in morphology and histology of conjunctival filtering bleb in rats can contribute to form ideal filtering blebs by interferencing the process of scarring.Objective This study was designed to observe the survival time,morphological and histopathological changes of conjunctival filtering bleb after filtering surgery.Methods Filtering surgeries were performed on 60 male adult Sprague-Dawley rats by implanting drainage tubes into the anterior chamber.The shape of filtering blebs was examined by slit lamp microscope 1 day,3,5,7,14,28 days after surgery.The filtering was typed according to the criteria of Kronfeld.Areas of the filtering bleb were measured and compared at various time points after surgery.Conjunctival and subconjunctival tissues at filtering zone were obtained 1 day,3,5,7,14,28 days after surgery,respectively,and hematoxylin and eosin staining was used for the histopathological evaluation.Results Well-elevated filtering blebs formed on the first day after surgery in 60 rat eyes.The survival time of filtering bleb was 7-17 days with the mean time of (11.93±2.23) days.Survival rate of the filtering blebs was 100％ in 1-5 days,77％ in 7 days,20％ in 14 days and 0 in 28 days after operation.The filtering blebs were functional (Ⅰ type) in 1-5 days after operation,23 eyes were functional in 7 days after operation (13 eyes were Ⅰ type,10 eyes were Ⅱ type),4 eyes were functional in 14 days after operation (2 eyes were Ⅰ type,2 eyes wereⅡtype).The filtering area shrunken from (7.50±1.08) mm2 to (1.83±0.35) mm2during the observational duration.The filtering blebs area of different days after surgery were statistically significant (F =180.056,P=0.000),and significant differences were found between any two timepionts after surgery (all at P =0.000).Histological examination showed that inflammatory finding was dominant in postoperative day 1-3,such as infiltration of inflammatory cells,vasodilatation and edema of tissue.However,proliferating manifestation became the main signs 5 days later,showing the increase of fibroblasts,neovascularization and collagen formation.Conclusions The model of conjunctival filtering blebs in rats can be successfully established by implanting silicone tube into anterior chamber.The inflammatory response,proliferation of fibroblasts and the accumulation of collagen fibers are involved in the scarring process of filtering blebs.