Thickening of inner retinal layers in the parafovea after bariatric surgery in patients with type 2 diabetes

Purpose Bariatric surgery dramatically improves the metabolic profile in patients with type 2 diabetes (T2D). We have previously reported a thickening of the retina after bariatric surgery and aimed to investigate these subclinical changes in retinal thickness and vessel calibres in more detail. Methods We examined 51 patients with T2D 2 weeks before and 1, 3, 6 and 12 months after bariatric surgery. Retinal thickness was measured with optical coherence tomography and automated segmentation in the fovea, parafovea and perifovea in each retinal layer. Retinal vessels were semiautomatically measured in a zone 0.5–1 disc diameters from the optic disc. Results The total macula thickened with a peak after 6 months in both univariate (2.7 ± 0.4 μm, p < 0.001) and multivariate analysis (2.2 ± 0.7 μm, p = 0.001). The thickening was most prominent in the parafoveal ring 1–3 mm from the centre and in the retinal nerve fibre layer and outer nuclear layer. A fall in HbA1c (p = 0.01) and longer duration of diabetes (p = 0.01) were associated with more thickening. The central retinal artery equivalent widened 22.1 μm (±8.9, p = 0.01) in the multivariate analysis 12 months postoperatively. A reduction in blood pressure was associated with less widening of the arterioles (p = 0.01). Conclusion Patients with T2D had thickening of the retina after gastric bypass surgery with a peak 6 months postoperatively. The thickening was most pronounced in the retinal nerve fibre layer and the outer nuclear layer of the parafovea. In multivariate analysis, the central retinal artery equivalent increased at 12 months.