Macular blood flow during pregnancy in patients with early diabetic retinopathy measured by blue-field entoptic simulation

To study macular capillary blood flow velocity during pregnancy and postpartum in diabetic women with minimal diabetic retinopathy.

Macular capillary blood velocity was measured using the blue-field entoptic simulation technique in 17 type I diabetic pregnant women with minimal background retinopathy and 10 healthy pregnant women at the 12th and 32nd-36th weeks of pregnancy and 3 months after delivery. Red-free fundus photography was also performed at all visits.

Capillary blood velocities at the 12th week of pregnancy were 1.09 +/- 0.37 mm/s in the diabetic women and 0.81 +/- 0.21 mm/s in the controls(P = 0.017), at the 32nd week 0.93 +/- 0.19 mm/s and 0.94 +/- 0.24 mm/s (P = 0.880), and 3 months postpartum 0.98 +/- 0.25 mm/s and 0.75 +/- 0.17 mm/s (P = 0.016), respectively. Analysis of variance indicated that there was a significant difference in leukocyte velocities during the course of pregnancy, with the flow being constantly elevated in diabetic women, but increasing by term in nondiabetic women (P = 0.039). Capillary flow velocity showed a statistically non-significant tendency to be higher in patients with HbA1c levels > 6.4%. Capillary flow velocity levels were not connected with changes in the number of microaneurysms. Capillary leukocyte density in the pregnant diabetic women did not differ from that of nondiabetic pregnant women.

These data suggest that during pregnancy there is a difference in retinal capillary blood flow between diabetic women with minimal background retinopathy and normal women. The lack of increase in blood flow in macular capillaries during diabetic pregnancy may reflect redistribution of retinal capillary flow during diabetic pregnancy or be due to altered rheological properties of blood components in diabetic pregnancy.