How to measure ophthalmic artery Doppler for pre-eclampsia screening.

BACKGROUND

Pre-eclampsia remains a leading cause of maternal and perinatal morbidity, affecting 3-5% of pregnancies globally. Screening in most hospital settings relies on risk factors, and only a few hospitals perform individualised risk screening using maternal factors, mean arterial pressure, uterine artery Doppler, and biochemical markers. Maternal ophthalmic artery (OA) Doppler has emerged as a significant marker of cerebrovascular and systemic hemodynamic adaptation. The peak systolic velocity (PSV) ratio reflects an integrated measure of cardiac output and peripheral vascular resistance.

OBJECTIVE

To provide a standardised, practical guide for acquiring high-quality ophthalmic artery Doppler measurements to be incorporated into clinical pre-eclampsia screening protocols.

METHODS

The guide outlines a nine-step acquisition technique using a high-frequency (7-18 MHz) linear-array transducer. Following a 5-min rest period, measurements are taken with the patient supine, and the probe is gently placed on the closed eyelid. The ophthalmic artery is identified superior and medial to the optic nerve, with the sample gate positioned 10-15 mm posterior to the globe. To ensure accuracy and reproducibility, an insonation angle of <20° is required, and measurements should be averaged from both eyes.

CLINICAL UTILITY: Ophthalmic artery Doppler provides significant incremental value to screening algorithms. In the second trimester, adding the PSV ratio improves preterm pre-eclampsia detection from 72% to 89% at a 10% false-positive rate. The technique is particularly advantageous in resource-limited settings due to its low equipment requirements and rapid learning curve. Safety is maintained by adhering to the ALARA principle, specifically keeping the Mechanical Index (MI) < 0.23 and Thermal Index (TI) < 1.0.

CONCLUSION

Ophthalmic artery Doppler is an accessible, safe, and reproducible tool for assessing maternal haemodynamics. Adhering to a standardised acquisition technique is essential for its successful integration into multimodal pre-eclampsia screening.