In vivo and in vitro study of suprachoroidal fibrin glue

The suprachoroidal space is preferred for many reasons for implantation of retinal prostheses or drug delivery systems. This study aimed to investigate the safety and feasibility of suprachoroidal fibrin glue (FG), one of the adhesives used to fix the implanted material. Human retinal pigment epithelium cells (hRPE) were cultured with FG, assayed with 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, and studied by transmission electron microscopy. A total of 48 rabbits were randomly divided into three groups to undergo surgery: group 1, 0.1 ml suprachoroidal FG; group 2, 0.1 ml suprachoroidal normal saline (control); group 3, 0.1 ml intravitreal FG. Slit-lamp examination, indirect ophthalmoscopy, fundus photography, fundus fluorescein angiography (FFA), indocyanine green angiography (IA), electroretinography (ERG), and histopathological examination were performed at various time points till 90 days after injection. No apoptosis changes of electron microscopy were observed in the hRPE cultured with FG, and the difference in the MTT test results was not statistically significant when compared with the control group (P > 0.2). One day after suprachoroidal injection, slight choroidal hemorrhage occurred. No severe intraocular reactions were observed in any of the three groups, and FFA and IA showed no edema or leakage around blood vessels. There was no significant difference in latency or amplitude of the ERG wave among the three groups (P > 0.1). Histopathological examinations showed the suprachoroidal FG induced localized inflammation (from acute inflammation to chronic phagocytosis) at the early stage and finally turned into fibrosis tissue. FG is feasible for suprachoroidal use, and no obvious toxic reaction was observed in either in vitro or in vivo studies.