We have recently reported that significantly more CD8(+) T-cell activity is present in the aqueous humor compared to peripheral blood. The aim of the current study is to investigate the effect of the ocular trauma on the number of the T lymphocyte subsets in the aqueous humor. CD4(+)/CD8(+) T-cell ratios in the aqueous and blood samples of 12 patients who suffered from traumatic iridocyclitis because of a corneal perforation were compared to those of patients with senile cataracts. We found a relatively higher CD4(+)/CD8(+) cell ratio in the aqueous samples of traumatized patients than cataractous patients. Meanwhile, no difference was present between the aqueous and blood samples of the traumatized patients with respect to the above-mentioned ratio. We suggest that one of the most important factors in maintaining a lower CD4(+)/CD8(+) cell ratio in normal aqueous humor compared to peripheral blood is an intact blood-aqueous barrier. Blood-aqueous barrier may play a participating role in the pathogenesis of immunosuppressive properties of the anterior chamber of the eye by establishing higher CD8(+) T-cell activity in the aqueous humor relative to the peripheral blood. (C) 1998 Japanese Ophthalmological Society.