PURPOSE: Multiple mitochondrial syndromes, such as Kearns-Sayre, involve the concurrence of diabetes mellitus and inherited pigmentary retinopathy. It is rare, however, for proliferative disease to develop in these patients as existing inner retinal dysfunction is thought to be protective. METHODS: To our knowledge this is the first description of proliferative diabetic retinopathy (PDR) in Kearns-Sayre syndrome. CONCLUSION: A number of additional considerations need to be recognised when treating PDR in Kearns-Sayre syndrome. Given the risk of further visual field losses with panretinal photocoagulation, there should be a preference for primary anti-VEGF therapy in a compliant patient. PDR in inherited retinal disease appears to be very anti-VEGF responsive and may not require the standard monthly frequency of treatment, even from initiation.