Out of the 13 complement proteins, C3b/iC3b was below the detectable level (< 8.02 ng/ml) in 3 cataracts and 2 RVO patients, C5a was detected in 4 cataract patients (from 1.65 ~ 18.91 pg/ml) but in all RVO patients. The gene discussed is C5; the disease is cataract.