The chapter starts with the electrophysiological and other changes that precede clinically evident retinopathy. The lesions that constitute diabetic retinopathy are then described with regard to their nature, location, distribution, and severity, providing definitions, classifications, and data on the natural course of retinopathy. The procedure and interpretation of fluorescein angiograms, when obtained, is provided. The chapter also includes the role of hyperglycaemia, hypertension, and pregnancy in the development and progression of retinopathy and a short description of the anterior segment findings that are relevant to the evaluation and management of retinopathy.