Everyone knows what it is like to look at someone’s eyes. A brief but powerful feeling may invade us: love, admiration, anxiety or even fear. We can also experience different sensations according to the length or circumstance of the gaze: Staring directly into someone’s eyes causes an arousal reaction, however, too much eye contact can make us uncomfortable; waiting for the last bus at midnight and seeing somebody looking at you may evoke fear, whereas you feel relaxed if this person averts gazing away from you.
For sure, some phrases like “the eyes are the window to the soul” and “I can see it in your eyes” sound poetic. But what else can the eyes tell us? And why am I, an Obstetrician, writing about this?
By this point, if you are an iPlacenta follower you should know that preeclampsia is one of the leading causes of maternal death worldwide, with an incidence of 5% to 10% of all pregnancies. But if you are not familiar with preeclampsia yet, let me tell you it is a pregnancy complication that can affect both the mother and the fetus. The woman develops high blood pressure, usually in the second part of the pregnancy or just after delivery. There are also signs of damage to other organs, most often the liver and kidneys. What about the baby? Since preeclampsia affects the arteries carrying blood to the placenta (uterine arteries), the fetus may receive inadequate blood and oxygen supply leading to fetal growth restriction or low birth weight.
Unfortunately, even though medical sciences have made immense advances in the last decades, we still do not have a cure for preeclampsia: the only available “treatment” is delivery, with the risk of adding prematurity to an already affected fetus.
Due to the negative consequences preeclampsia may have, the scientific community has made enormous efforts to identify high-risk pregnancies, in order to adopt preventive strategies and thus reduce morbidity and mortality. Prediction models for PE usually consist of a combination of maternal characteristics, uterine artery Doppler and biochemical indices, but lately several peripheral vessels have also been investigated as potential markers. And it is in this scenario that we go back to our topic: the eye.
The story began almost 30 years ago, when the first paper about the Ophthalmic Artery Doppler and preeclampsia was published: "Evaluation of the Ophthalmic Artery doppler in women with preeclampsia" by Hata et al (1) was released in The Lancet in 1992, describing the changes in the named artery in women with normal pregnancies and preeclampsia. Following that first publication, more than 50 papers have been published from groups all over the world.
The technique is very simple: The patient is lying flat on her back and remains in this position for a 5-minute period of rest. A small quantity of gel is applied and an ultrasound transducer is placed on the closed upper eyelid. The ophthalmic artery is easily identified and then we analyze the different velocities of the blood while going through the artery. The mean time required for ophthalmic Doppler analysis is less than 2 minutes.
This means that the technique is easy, fast, not affected by maternal obesity and some women even said it was relaxing!
Once we have the images, we need to analyze them. We will see the wave has 2 different “peaks” and what has been shown to be the better predictor of preeclampsia, is the ratio between these two peaks. But let’s not get too technical.
After this introduction, let me tell you that my project is about the Ophthalmic artery doppler in complicated pregnancies. Several values are expected to be different in women who develop preeclampsia or fetal growth restriction. We expect to identify novel ultrasound indices that can potentially improve prediction of hypertensive pregnancies; and ophthalmic artery is a great candidate to be employed even in low resource settings with limited technical equipment.
By the end of the day, the eyes are not only the window to our soul…Maybe they are also the window for a new prediction model. Who would have said that the eye could give us so much information on pregnancy???
1. (Hata T, Senoh D, Hata K, Kitao M. Ophthalmic artery velocimetry in pregnant women. Lancet 1992; 340:182–183)
Carolina Di Fabrizio is an Early Stage Researcher of iPlacenta.
About the blog
Being a PhD student in a European training network is a life-changing adventure. Moving to a new country, carrying out a research project, facing scientific (and cultural) challenges, travelling around Europe and beyond… Those 3 years certainly do bring their part of new - sometimes frightening - but always enriching experiences.