Evaluation of color vision and contrast sensitivity in diabetic patients without retinopathy

Diabetes mellitus is a common disease with devastating effects characterized by increased high glucose level due to defect in insulin production, insulin action or both. Diabetes mellitus occurs when the pancreas cannot produce enough insulin or the cell in the body has resistance to insulin.1 The most common type of diabetes is type 1 (5%) and type 2 diabetes is (95%). The estimated number of people over 18 years of age with diagnosed and undiagnosed diabetes is 30.2 million in the United States.2 Among the most populated countries of the world Pakistan ranks eighth in the prevalence of diabetes. In Pakistan about 6.2 million populations are suffering from diabetes and one in every third diabetic patients has diabetic eye disease.3 The diabetes mellitus disturbs the physiology of the retinal cells and its pathogenesis. Retinal neuro-degeneration such as alteration in the retinal ganglion cells and inner retinal neurons can cause various forms of visual defects such as decreased contrast sensitivity and impaired color vision and temporal perception. All these changes occur before changes in vascular morphology and visual acuity.4 Approximately 7-29% of diabetic patients attending general medical outpatient department have diabetic retinopathy and two-thirds of diabetic have an increased risk of visual impairment.5 According to the World Health organization there are 285 million people are visually impaired and contrast sensitivity is one of the most common leading cause of visual impairment. Worldwide, Diabetic retinopathy with impaired vision, decrease color vision and contrast sensitivity is the leading cause of legal blindness, Between 20 to 74 year of age but it can be prevented through proper glycemic control.4