Reference values of maternal ophthalmic artery doppler variables in the first trimester of normal pregnancy.

Background: The aim of this study was to establish normative data for ophthalmic artery Doppler variables in the first trimester of normal pregnancy.

Methods: Maternal ophthalmic artery Doppler signals were recorded in 409 singleton pregnancies at 11-14 weeks' gestation, in mothers presenting consecutively for routine antenatal care. Pulsatility and resistance indices (PI, RI), peak systolic velocity (PSV), first peak diastolic velocity (PD1), and peak ratio (PR) were measured.