The influence of aging on the blood-aqueous barrier function was assessed by measuring aqueous flare intensity in 203 normal eyes of healthy human subjects aged 20 to 79 years, using the recently developed laser flare-cell meter. The flare intensity correlated well with age (r = 0.502, Spearman r = 0.503, P = 0.00), and the intensity values in the subjects with their ages in the 6th, 7th and 8th decade were significantly higher than the values in the subjects in their 3rd decade (P less than 0.01).