Fundoscopy of a melanocytoma (dark mass) on the retina (light-sensitive membrane) of the left eye of a female patient. The melanocytoma is a benign (non-cancerous) tumour, which has grown over part of the optic disc (centre). The optic disc is the region where the optic nerve and retinal blood vessels enter the eye. Although the tumour is benign, its growth may damage the optic nerve, leading to defective vision.