E ditorial Debate continues: Gastric bypass surgery does not increase the risk for sight-threatening diabetic retinopathy Acta Ophthalmol. ª 2018 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd doi: 10.1111/aos.13990 I read with great interest the article by Moren et al. (2018) with refer- ence to their research on ‘Gastric bypass surgery does not increase the risk for sight-threatening diabetic retinopathy’. I thank them for their important contribution in clarifying an enigmatic disease complex that was lacking definitive data and that had insufficient guidelines for treatment and follow-up. The authors investigated the occur- rence and level of diabetic retinopathy (DRP) before and after planned bar- iatric surgery and the potential risk factors for deterioration of DRP. How- ever, of the 117 patients in this study, the total number of the eyes with severe non-proliferative DRP and prolifera- tive DRP were lower than 2% (two patients). This means that there were almost no patients with serious diabetic eye disease. However, a previous study (Murphy et al. 2015) reported that higher preoperative DRP grade is an independent risk factor for the pro- gression of DRP following bariatric surgery. On the other hand, the present study reported a significant reduction of glycated haemoglobin (HbA1c) levels, and there is a known paradox- ical relationship between the rapid reduction in HbA1c and exacerbated DRP (Brinchmann-Hansen et al. 1985). I would like to ask the research- ers, do they think that having a low- grade DRP population is the reason for these results? Nutrient deficiency is another prob- lem related to bariatric surgery, and a recent study reported (Kikkas et al. 2018) a cumulative ferritin deficiency in 47% of the patients. Iron deficiency is a very old phenomenon that is accused of being a risk factor for the progression of DRP (Shorb 1985). I would like to ask the researchers if they had any patients with iron defi- ciency or another nutritional deficiency such as B12? To sum up, I believe that further studies will reveal new aspects on DRP and its relation to bariatric surgery not only for mild to moderate diseases but also for serious DRP. However, with the current knowledge available, we still have to be careful of the conse- quences. Ozkan Sever Department of Ophthalmology, Namık Kemal University School of Medicine, Tekirdag, Turkey References Brinchmann-Hansen O, Dahl-Jorgensen K, Hanssen KF & Sandvik L (1985): Effects of intensified insulin treatment on various lesions of diabetic retinopathy. Am J Oph- thalmol 100: 644–653. Kikkas EM, Sillakivi T, Suumann J, Kirsim€ agi € U, Tikk T & V€ ark PR (2018): Five year outcome of laparoscopic sleeve gastrectomy, resolution of comorbidities, and risk for cumulative nutritional deficiencies. Scand J Surg [Epub ahead of print]. Moren A, Sundbom M, Ottosson J & Gran- stam E (2018): Gastric bypass surgery does not increase the risk for sight-threatening diabetic retinopathy. Acta Ophthalmol 96: 279–282. Murphy R, Jiang Y, Booth M et al. (2015): Progression of diabetic retinopathy after bariatric surgery. Diabet Med 32: 1212– 1220. Shorb SR (1985): Anemia and diabetic retinopathy. Am J Ophthalmol 100: 434– 436. 1 Acta Ophthalmologica 2018