Aqueous Humour and Serum Levels of Nitric Oxide, Malondialdehyde and Total Antioxidant Status in Patients with Type 2 Diabetes with Proliferative Diabetic Retinopathy and Nondiabetic Senile Cataracts.

OBJECTIVES: Diabetic retinopathy is associated with enhanced oxidative stress and/or reduction of antioxidant status. Several studies have examined the oxidative agents, such as nitric oxide (NO) and malondialdehyde (MDA), in the body fluids of patients with diabetes. However, total antioxidant status (TAS) in the aqueous humour of patients with diabetes has not been determined to date. To address this issue, we analyzed the aqueous humour and serum levels of NO, MDA and TAS in patients with type 2 diabetes and nondiabetic senile cataracts.

METHODS: This prospective study included 35 patients with type 2 diabetes and 35 age- and sex-matched healthy subjects in whom cataract surgery was indicated. Aqueous humour and serum MDA, NO and TAS levels were determined by spectrophotometric methods, respectively.

RESULTS: The analysis of MDA levels in the serum and aqueous humour revealed no significant differences in any of the groups (p>0.05). At the level of aqueous humour, patients with type 2 diabetes had significantly increased NO levels, compared to the controls (p=0.003). The control group also presented significantly higher TAS levels than the subgroup with type 2 diabetes in serum (p=0.001). However, there were no significant differences in the TAS levels of aqueous humour and serum NO levels in the groups (p>0.05).

CONCLUSIONS: Our results seem to demonstrate that the development of diabetic retinopathy is associated with high levels of aqueous humour NO and reduced serum antioxidant defenses. Therefore, inhibition of reactive oxygen species production and substitution of serum antioxidant status may be a therapeutic target for eye diseases associated with oxidative stress.