This document reviews approaches for classifying diabetic retinopathy using computer vision and artificial intelligence. Diabetic retinopathy is a leading cause of blindness that affects blood vessels in the retina. The document discusses how researchers have developed automated tools to help detect lesions and classify stages of diabetic retinopathy in retinal images, in order to assist doctors and allow for earlier detection and treatment. It reviews various studies that have used techniques like image processing, machine learning and deep learning for tasks like blood vessel extraction, lesion detection and multi-class classification of diabetic retinopathy severity levels.