Monitoring of Diabetic Retinopathy in relation to Bariatric Surgery: a Prospective Observational Study

Background: To investigate the need for closer perioperative monitoring of diabetic retinopathy in patients with type 2 diabetes undergoing bariatric surgery. Methods: Prospective observational clinical study of 56 patients with type 2 diabetes undergoing bariatric surgery. The patients were examined with 7-field fundus images and optical coherence tomography scans 2 weeks before and 1, 3, 6 and 12 months after bariatric surgery. Worsening was defined as a two-step change in the Wisconsin Epidemiologic Study of Diabetic Retinopathy scale or appearance or worsening of macular edema. Postoperative changes were analyzed in a mixed model. Results: Six patients (11 %) had any worsening at any visit, and three (5 %) persisted at 1 year. Of the 24 patients with preoperative retinopathy, 4–13 % worsened and 9–22 % improved, with significant overall improvement at 6 months (p = 0.01). Only one (3%) of the 32 patients without preoperative diabetic retinopathy had a transient worsening at 6 months. No patients developed macular edema, but the whole cohort had a minor increase in center point foveal thickness that peaked 6 months postoperatively. The patients were required to have good glucose control preoperatively where HbA_1c was 6.4 ± 1.9 %. Conclusions: Diabetic retinopathy was clinically stable after bariatric surgery, and none of the observed changes would have resulted in a changed screening interval at our center. This supports adherence to regular diabetic retinopathy screening guidelines following bariatric surgery in well-controlled patients. A clinically negligible but statistically significant foveal thickening 6 months postoperatively warrants further study.