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Troels Brynskov, Caroline Schmidt Laugesen, Torben Lykke Sørensen; Constriction of retinal arterioles by 3 and 12 months after gastric bypass surgery in type 2 diabetic patients with poor glycaemic control. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3358.
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© ARVO (1962-2015); The Authors (2016-present)
Gastric bypass surgery induces large metabolic changes and rapidly normalizes blood glucose levels in type 2 diabetic patients, but the consequences for the retinal vasculature are largely unknown. We hypothesized that gastric bypass surgery could lead to early changes in retinal vessel diameters - a marker of endothelial function previously associated with the development of diabetic retinopathy - in a cohort of patients with type 2 diabetes.
This was a prospective, observational clinical study. A total of 53 eyes of 53 patients underwent thorough ophthalmologic baseline examination 2 weeks before Roux-en-Y gastric bypass surgery. All patients had type 2 diabetes. The examinations were repeated at 3 and 12 months after the surgery. Retinal arterioles and venules were semi-automatically measured using the “big-six”-method on a fundus picture taken of the optic disk. We analyzed the data using paired t-tests. Subgroup analysis was performed using a linear regression model adjusting for sex, age, change in body mass index, change in mean arterial pressure (MAP), baseline HbA1c, and change in HbA1c.
Higher HbA1c at baseline led to a decrease in the central retinal artery equivalent (CRAE) of 2.2 µm per % HbA1c (±2.0, p=0.04) at 3 months and of 3.0 µm per % HbA1c (±2.4, p=0.01) at 12 months. A fall in blood pressure compared to baseline was associated with a decrease in both CRAE (p=0.006) and central retinal vein equivalent (CRVE, p=0.01) at 3 months but did not reach significance at 12 months (p=0.051 and p=0.12 respectively). All retinal vessel diameter measures for the whole group were unchanged: at 3 months after surgery CRAE had decreased by a mean of 1.3 µm (±1.9, p=0.17) while CRVE had increased by a mean of 0.59 µm (±2.7, p=0.66) and the Arterio-Venous Ratio (AVR) decreased by a mean of 0.0042 (±0.011, p=0.44). At 12 months CRAE decreased a mean of 0.95 µm (±2.2, p=0.39), CRVE decreased a mean of 2.2 µm (±2.7, p=0.12) and AVR increased a mean of 0.0015 (±0.011, p=0.79).
Patients with poorer glycaemic control as measured by HbA1c at baseline experienced an early and sustained constriction of the retinal arterioles in the first year after gastric bypass surgery. This is an encouraging finding, as other longitudinal studies have identified arteriolar constriction as an early marker for improvement in diabetic retinopathy.
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