Background Choroidal neovascularization (CNV) is the leading cause of blindness in many eye diseases such as age related macular degeneration. The main pathology of CNV contains bleeding, exudation and scar formation at the neovascular site. Recently, many new therapies had been used for the CNV.  Chitooligosaccharides (COS) was considered as a new tool in the inhibition of neovascularization.

Objective The purpose of this study is to investigate whether the COScould inhibit the laser-induced CNV model in Brown Norway rats.

Method The laser-induced CNV of BN rats were used as pharmacodynamic study animal model, CNV area in the choroidal flat mounts as evaluation index to inspect the inhibition effect of 5μg、25μg、50μg of COS and normal saline. And also, CNV was observed by fluorescein fundus angiography(FFA) after laser photocoagulation. The retinal toxicity of COS were evaluated  on normal rats following an intravitreous injection COS(5μg、25μg、50μg).

Results CNV area analysis proved the 50μg COS can inhibit the neovascularization significance. Reductions in CNV lesion size of 53.8% vs Control groups. Treatment of BN rats with COS(5μg、25μg) 1 days after laser photocoagulation resulted in CNV that had no significant difference in area and fluorescence leakage in FFA compared with CNV in rats treated with normal saline. Rats treated with 50μg COS had a statistically significant decrease in the area of CNV and slighter leakage at the rupture site in FFA compared with other groups. Light microscopy indicated theCOSshows no toxicity.