Markers of oxidative damage of proteins and lipids in patients with senile cataract

Senile cataract is the most prevalent cause of blindness in the world. Various factors are involved in the pathogenesis of senile cataract. The most important factor is oxidative stress. Oxidative stress is due to increased production of free radicals or reduction of antioxidant capacity in the body. Free radicals cause oxidative damage to cellular components and produce oxidative stress markers. The aim of the present study was to compare markers of oxidative stress associated with proteins andlipids in patients with senile cataract and healthy individuals. In this case-control study that was conducted on 45 patients with senile cataract and 45 healthy peoples, oxidative stress markers of proteins and lipids were measured in serum. Protein carbonyl and reduced total thiol as markers of protein oxidation and malondialdehyde as marker of lipid oxidation were investigated. SPSS 18 and appropriate statistical test were used for comparing average serum level makers of oxidative stress between patient and control groups. Serum protein carbonyl level in patient and control groups was 0.233±0.096 and 0.248±0.104, respectively, and there was no statistically significant difference (P=0.265), but serum malondialdehyde level was found significantly higher in patient group (10.32±2.53) than that measured in the control group (6.15±1.16) (P=0.001). The level of serum reduced total thiol level in patient and control group was 277.5±104.2 and 392.5±121.3, respectively. Serum total thiol was significantly lower in the senile cataract group compared with control group (P<0.001). Oxidation of lens proteins and lipids is a reason for cataract formation. Increased production of free radicals with aging and subsequently creation of oxidative stress conditions lead to oxidation lipids and thiol groups of proteins and can cause increased senile cataract risk. In present study decreased level of serum reduced total thiol and increased level of malondialdehyde in patient group in comparison with controls suggest involvement of oxidative stress in the development of senile cataract formation.