 patients with age related cortical cataracts who are otherwise healthy cases and two control groups; first systemically healthy subjects with ocular problems other than cataract and a second control group of patients with impaired renal functions and are not on dialysis treatment and thus have elevated serum urea levels. Slit lamp examination was performed to evaluate crystalline lens for opacities. Measurement of serum urea was done for all study subjects. Aqueous humor urea concentration was done only for the group of patients who are planned to have intraocular surgery. For that purpose, 0.1 ml of aqueous humor will be aspirated at the start of routine intraocular surgery. 