Plasma redox status and premature onset of senile cataract

Dysfunction of the lens due to opacification is called cataract. Senile cataract is associated with old age. It is estimated that the need for cataract extractions would be diminished by half if onset of cataract would be delayed by only ten years. It thus appears crucial to have a better characterization of the etiology of cataract to detect modifiable factors. It seems that oxidative stress may play an important role in cataractogenesis. Also, it was demonstrated that some plasma constituents correlate with human cataract location.

We supposed that in senile cataract the oxidative insult may be systemic and not only at the lens level. The aim of our study was to evaluate the blood redox status in cataractous patients aged between 50-65.

The blood samples were collected from 15 patients with pure nuclear cataract and/or posterior subcapsular cataract, without metabolic or somatic diseases and from 15 age and sex matched controls. Carbonyl content of plasma proteins was evaluated with 2,4-dinitro-phenyl-hydrazine method. The a-oxoaldehydes were measured in the presence of Girard T reactive. The lipid peroxides concentration was assessed measuring malondialdehyde concentration using thiobarbituric acid. For the other plasma parameters we used kits.

The levels of plasma protein carbonyls and malondialdehyde were significantly increased in the cataract group. The plasma levels of: total proteins, globulins, total thiols, fasting glucose, triglycerides and alpha-oxoaldehydes were not modified comparing the groups. Plasma concentrations of albumin and cholesterol were significantly decreased.

The study underlies the presence of an increased plasma oxidative stress in cataractous patients. The abnormal oxidative stress parameters are linked to the premature development of senile cataract. Preventive therapy in order to delay the onset of senile cataract requires more research work on plasma oxidative stress markers.