Hyperhomocysteinemia, oxidative stress and total thiols in retinal inflammatory diseases – Age Related Macular Degeneration, Eales’ and Central Retinal Vein Occlusion

Abstract

Abstract: : Purpose: A moderately elevated plasma concentration of homocysteine is reported as an independent risk factor for coronary, cerebral and peripheral atherosclerotic vascular disease. There is a need to investigate the possible biochemical and pathological mechanisms to explore the link between elevated homocysteine and retinal diseases involving vascular inflammations. This study assesses the relationship between the levels of homocysteine and total thiol and glutathione (redox status) in Age Related Macular Degeneration (ARMD), Eales, Disease (ED) and Central Retinal Vein Occlusion (CRVO). Methods: A prospective analysis was done in consecutive cases of ARMD (n=16) ED (n=18) and CRVO( n=20) along with age and sex matched healthy controls for ED and CRVO (n=19) and for ARMD (n=20). Estimation of fasting plasma Homocysteine (ELISA), total thiols (A_412–) and Glutathione (Ex360/ Em400) was done in ARMD and ED patients and in corresponding controls. Patients with systemic complications, elevated cholesterol, smoking, alcohol abuse and under vitamin supplements were excluded from the study. Results:  

A significant negative correlation was seen between homocysteine and total thiols in ARMD alone. Conclusions: The results reveal a moderately elevated homocysteine in all the 3 retinal vascular inflammations in the order of ARMD, ED and CRVO. A diminished thiol pool and GSH was seen in ARMD and ED. Reduced levels of total thiols and GSH reflect an overall decreased antioxidant status of plasma. Homocysteinemia could lead to production of excessive amounts of superoxide ion and hydroxyl free radical (J. Nutr. 2000,130:369S–372S). The data suggest an altered redox status associated with oxidative stress induced by hyperhomocysteinemia, in the retinal inflammatory diseases such as ARMD, ED and CRVO. Support : Vision Research Foundation, Sankara Nethralaya.

Keywords: retinitis • oxidation/oxidative or free radical damage • age–related macular degeneration