Diabetic retinopathy (DR) is a sight-threatening condition occurring in persons with diabetes, which causes progressive damage to the retina. People with diabetes mellitus need annual screening to check for the development of diabetic retinopathy (DR).The early detection and diagnosis of DR are vital for saving the vision of diabetic persons. The early signs of DR which appear on the surface of the retina are the dark lesions such as microaneurysms (MAs) and hemorrhages (HEMs). The shape and count of these features are used to indicate the severity level of diabetic retinopathy. A computer aided diagnosis system can help to reduce the burden on the ophthalmologist and rapidly identify the most severe cases. So in this paper, a survey of different red lesion detection techniques and automated analysis are discussed.