The effect of pregnancy on retinal hemodynamics in diabetic versus nondiabetic mothers

Abstract

PURPOSE: To investigate retinal circulatory changes that occur during the third trimester of pregnancy in diabetic patients and control subjects. METHODS: Bidirectional laser Doppler velocimetry and monochromatic fundus photography were used to assess the retinal circulation in seven pregnant diabetic patients and 13 age-matched pregnant control subjects. Retinal venous diameter (D), maximum erythrocyte velocity (Vmax), and retinal volumetric blood flow rate (Q) were measured in one eye of each subject during the third trimester of pregnancy (DPREG, VmaxPREG, and QPREG, respectively). These measurements were repeated during the postpartum period for both diabetic patients (11 ± 7 weeks postpartum) and control subjects (16 ± 6 weeks postpartum; P = .203; DPOST, VmaxPOST, and QPOST). RESULTS: In control subjects, DPREG was significantly reduced by −4.5% ± 4.4% (mean percent difference ± 1 standard deviation; paired t test, P = .006) relative to DPOST. In diabetic women, DPREG was also significantly reduced by −8.1% ± 3.2% compared with DPOST ( P = .001), a change that was significantly larger than that seen in control subjects (unpaired t test; P = .035). Compared with QPOST, QPREG was reduced by −7.1% ± 14.2% ( P = .123), in control subjects. In diabetic women, QPREG was significantly decreased by −18.4% ± 9.3% compared with QPOST ( P = .012). This reduction in QPREG was significantly greater in diabetic patients than in nondiabetic control subjects (unpaired t test, P = .040). No significant differences between VmaxPREG and VmaxPOST were observed in either diabetic patients (−3.1% ± 12.9%; P = .400) or control subjects (+1.9% ± 14.4%; P = .787). CONCLUSIONS: Retinal venous diameter is decreased during the third trimester of pregnancy in both diabetic and nondiabetic mothers. This decrease is significantly larger in diabetic than in nondiabetic mothers. In addition, we observed a reduction in retinal volumetric blood flow in diabetic patients during pregnancy that was significantly larger than that present in nondiabetic women. This fall in retinal volumetric blood flow in diabetic patients may exacerbate retinal ischemia and hypoxia and thus may be associated with the progression of diabetic retinopathy.