Retinal Vessels Diameter Changes during Pregnancy in Type 1 Diabetes

Objective: Investigate how pregnancy-induced hormonal and hemodynamic changes affect retinal vessels caliber dynamic and the course of diabetic retinopathy. Methods: Retinopathy grading and vessel diameter measurement using digital fundus photographs in women with diabetes type 1 taken no more than one year before conception, during week 10 and/or 22, week 34, and within one year after delivery. Calibers were measured using a custom-developed semi-automated computer algorithm which identified the six largest arteries and six largest veins and calculated the central retinal artery equivalent (CRAE) and central vein equivalent (CRVE) diameters. Glycemic control was assessed quarterly by HbA1c. Systolic and diastolic blood pressure was assessed at week 10, 22 and 34. Results: Photographs at baseline, weeks 10, 22, 34 and after delivery were available in 28 patients, of whom 24 did not progress in retinopathy. For those whose level of retinopathy remained stable CRAE constricted from 138.80 ± 21.27 μm at baseline to 129.88 ± 13.97 μm at week 10 (p = 0.0379) CRVE constricted from 195.16 ± 24.98 μm at baseline to 185.97 ± 21.96 μm at week 10 (p = 0.0400). The patients with retinopathy progression had a CRAE of 131.67 ± 13.37 μm at baseline and 132.08 ± 11.07 μm at week 10 (p = 0.34) while CRVE was 195.33 ± 24.92 μm at baseline and 204.27 ± 10.18 μm at week 10 (p = 0.16). Progressors had higher blood pressures at week 10. Conclusion: Retinal vessels constricted between prepregnancy and first trimester in women who did not experience diabetic retinopathy progression. The study suggests that the vessels constriction seen in early pregnancy contributes to reduce the risk of gestational microvascular complications and progression of diabetes in the eye.