Review on Detection and Classification of Diabetic Retinopathy Lesions Using Image Processing Techniques

Diabetic retinopathy is one of the most common causes of blindness. However, efficient therapies do exist. An accurate and early diagnosis and correct application of treatment can prevent blindness in more than 50% of all cases.[1] Diabetic Retinopathy (DR) is the leading cause of blindness among working-age Americans. It is shown that early diagnosis and timely treatment could efficiently prevent visual loss. [2] Diabetic retinopathy (DR) is a common retinal complication associated with diabetes. It is a major cause of blindness in both middle and advanced age groups. According to the National Diabetes Information data (US). [3], Diabetic retinopathy (damage to the retina) caused by complications of diabetes, which can eventually lead to blindness. It is an ocular appearance of diabetes, a universal disease, which affects up to 80 percent of all patients who have had diabetes for 10 years or more. Although these intimidating statistics, research indicates that at least 90% of these new cases could be reduced if there was proper and alert treatment and monitoring of the eyes. The longer a person has diabetes, the higher his or her chances of developing diabetic retinopathy. In the United Kingdom everyone with diabetes aged twelve and above should be invited, at least annually, for retinal screening using digital retinal photography.[4] In diabetic retinopathy there are some diseases like, Microaneurysms, Microaneurysms are the first clinically detected lesions. It is tiny swelling in the wall of a blood vessel, It appears in the retinal capillaries as a small, round, red spot located in the inner nuclear layer of the retina. Hemorrhages, Hemorrhages are located in the middle layer of the retina. Retinal hemorrhage is the abnormal bleeding of the blood vessels in the retina. They have a „dot‟ and „blot‟ configuration. Cotton Wool Spot, Cotton wool spots are an abnormal finding on fundoscopic exam of the retina of the eye. They appear as fluffy white patches on the retina. They are caused by damage to nerve fibers and are a result of accumulations of axoplasmic material within the nerve fiber layer. The nerve fibers are damaged by swelling in the surface layer of the retina. Exudates are yellow flecks are called hard exudates. They are the lipid residues of serous leakage from damaged capillaries. The optic disc or optic nerve head is the location where ganglion cell axons exit the eye to form the optic nerve. There are no light sensitive rods or cones to respond to a light stimulus at this point. This causes a break in the visual field called "the blind spot" or the "physiological blind spot".