Contents I Introduction
Diabetes is a chronic disorder that causes high blood sugar. Diabetic patients are usually affected by different eye diseases like diabetic retinopathy (DR), Diabetic Macular Edema (DME), and glaucoma. DR is one of the major diseases of diabetes and it remains as the primary cause of vision impairment. The symptoms of DR are blurred vision, floaters, sudden vision loss [1]. Diabetic retinopathy itself is classified into two types, Non-Proliferative Diabetic Retinopathy (NPDR) and Proliferative Diabetic Retinopathy (PDR) [2]. The early stage of DR is called NPDR. In that stage, the blood vessels in the retina are weakened and sometimes leaking fluid and blood into the retina. The severe type of DR is known as PDR, damaged blood vessels or growth of new abnormal blood vessels in the retina and can leak into the clear jelly-like substance that filled in the centre of the eye [3].