This kit was based on sandwich enzyme-linked immune-sorbent assay technology. Anti- VEGF antibody was pre-coated onto 96-well plates. And the biotin conjugated anti- VEGF antibody was used as detection antibodies. The standards, test samples and biotin conjugated detection antibody were added to the wells subsequently, and washed with wash buffer. HRPStreptavidin was added and unbound conjugates were washed away with wash buffer. TMB substrates were used to visualize HRP enzymatic reaction. TMB