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

PURPOSE: To investigate retinal circulatory changes that occur during the t hird trimester of pregnancy in diabetic patients and control subjects. METHODS: Bidirectional laser Doppler velocimetry and monochromatic fundus p hotography were used to assess the retinal circulation in seven pregnant di abetic patients and 13 age-matched pregnant control subjects. Retinal venou s diameter (D), maximum erythrocyte velocity (Vmax), and retinal volumetric blood flow rate (a) were measured in one eye of each subject during the th ird trimester of pregnancy (DPREG, VmaxPREG, and QPREG, respectively). Thes e 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 re duced by -8.1% +/- 3.2% compared with DPOST (P = .001), a change that was s ignificantly larger than that seen in control subjects (unpaired t test; P = .035). Compared with QPOST, QPREG was reduced by -7.1% +/- 14.2% (P = .12 3), in control subjects. In diabetic women, QPREG was significantly decreas ed by -18.4% +/- 9.3% compared with QPOST (P = .012). This reduction in QPR EG was significantly greater in diabetic patients than in nondiabetic contr ol 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 trimeste r of pregnancy in both diabetic and nondiabetic mothers, This decrease is s ignificantly larger in diabetic than in nondiabetic mothers. In addition, w e observed a reduction in retinal volumetric blood flow in diabetic patient s during pregnancy that was significantly larger than that present in nondi abetic women. This fall in retinal volumetric blood flow in diabetic patien ts may exacerbate retinal ischemia and hypoxia and thus may be associated w ith the progression of diabetic retinopathy. (Am J Ophthalmol 1999;128: 477 -484, (C) 1999 by Elsevier Science Inc. All rights reserved.).