Doppler velocimetry of the ophthalmic artery in normal pregnancy: reference values

This study aimed at analyzing the correlation between ophthalmic Doppler indices and gestational age (GA) in healthy patients with singleton pregnancies. Intraobserver reproducibility and right-to-left eye correlation were also evaluated.

Healthy pregnant women (n = 289) at 20 to 40 weeks' GA were evaluated. The resistive index (RI), pulsatility index (PI), and peak ratio (PR) were determined by 2 measurements in each eye. Comparisons were performed first between the 2 measurements in each eye and later between the right and left eyes. Spearman rank correlation was used to analyze the relationship of the RI, PI, and PR with GA. Linear regression analysis was also performed.

No significant differences were found between the values obtained for the first and the second measurements in each eye and those for the RI, PI, and PR in the right and left eyes. There was a significant decrease in RI and PI values with advancing GA, however (rho = -0.264 and -0.1192, respectively), with low R(2) values for both. Thus, only a small proportion of the variations observed in the RI and PI was associated with changes in GA. No significant difference was found between the PR values with regard to GA intervals.

Doppler velocimetry is a reproducible technique for evaluation of the RI, PI, and PR in the ophthalmic artery. Unilateral analysis of these indices can be used. Linear regression analysis indicated that other factors were associated with a decrease in the RI and PI values with advancing GA. No significant change was observed in the PR values throughout normal pregnancy.