The retina and optic nerve.
D003930:Diabetic Retinopathy; D005128:Eye Diseases / Q000175:diagnosis / Q000503:physiopathology; D005134:Eye Neoplasms; D006801:Humans; D009900:Optic Nerve / Q000503:physiopathology; D009902:Optic Neuritis; D012160:Retina / Q000503:physiopathology; D012162:Retinal Degeneration; D012163:Retinal Detachment; D012164:Retinal Diseases; D012171:Retinal Vessels; D012173:Retinitis; D014652:Vascular Diseases