OXIDATIVE STRESS IN DIABETIC RETINOPATHY

The Role of Oxidative Stress in Diabetic Retinopathy



Table of Content

INTRODUCTION3

Background of the Study3

Type 1 Diabetes6

Type 2 Diabetes7

Overview of Diabetes (Type 1&2) and Oxidative Stress8

Hyperglycemia, Diabetes and Oxidative Stress9

Lipid Peroxidation and Diabetes12

Possible Diabetes Complications12

Damages Prompted By Oxidative Stress14

Oxidative Stress and Diabetic Complications15

Insulin Treatment and Diabetes Complications16

Physiologic and Pathophysiologic Procedures17

Function of Oxidative Stress18

Hyperglycemia and Oxidative Stress19

Diabetic Complications20

Oxidative Stress in Insulin Resistance and Diabetes21

Oxidative Stress in Insulin Resistance Caused by Agents22

Oxidative Stress and Diabetic Retinopathy23

Clinical Relevance of the Ages-Rage System in Diabetic Retinopathy26

REFERENCES28

INTRODUCTION

Background of the Study

Oxidative stress is a cytopathic consequence of excessive production of ROS and the suppression of ROS removal by antioxidant defense system is implicated in the development of many diseases, including Alzheimer's disease, and diabetes and its complications (Renu & Kowluru, 2007: 25). Oxidative stress again represents an imbalance between the production and manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Retinopathy, a debilitating micro vascular complication of diabetes, is the leading cause of acquired blindness in developed countries. Retinopathy is one of the most severe ocular complications of diabetes and is a leading cause of acquired blindness in young adults. The cellular components of the retina are highly coordinated but very susceptible to the hyperglycemic environment.

Diabetic retinopathy (DR) can be defined as damage to microvascular system in the retina due to prolonged hyperglycaemia. The prevalence of DR in the Chennai Urban Rural Epidemiology (CURES) Eye Study in south India was 17.6 per cent, significantly lower than age-matched western counterparts (L'Esperance, 1990: 661). However, due to the large number of diabetic subjects, DR is likely to pose a public health burden in India. Hypertension did not play a major role in this cross-sectional analysis. The role of oxidative stress, atherosclerotic end points and genetic factors in susceptibility to DR has been studied. It was found that DR was associated with increased intima-media thickness and arterial stiffness in type 2 Indian diabetic subjects suggesting that common pathogenic mechanisms might predispose to diabetic microangiopathy. Curcumin, an active ingredient of turmeric, has been shown to inhibit proliferation of retinal endothelial cells in vivo (Yamagishi , 2005: 2279). Visual disability from DR is largely preventable if managed with timely intervention by laser. It has been clearly demonstrated that in type 2 south Indian diabetic patients with proliferative DR who underwent Pan retinal photocoagulation, 73 per cent eyes with good visual acuity (6/9) at baseline maintained the same vision at 1 yr follow up. There is evidence that DR begins to develop years before the clinical diagnosis of type 2 diabetes. Our earlier study demonstrated that DR is present in 7 per cent of newly diagnosed subjects, hence routine retinal screening for DR even at the time of diagnosis of type 2 diabetes may help in optimized laser therapy. Annual retinal examination and early detection of DR can considerably reduce the risk of visual loss in diabetic ...