Moreover, by comparing the levels of complement proteins/factors in aqueous humour and plasma between RVO patients and the control group, after considering age factors, the concentrations of C1q, C4, C4b, C3b/iC3b, C5, CFB, CFD, CFI, and CFH in the RVO patients were significantly higher than those in the cataract patients. This evidence concerns the gene C4A and cataract.