The complications of long-standing severe and acute severe elevations in systemic blood pressure (hypertension) may involve large vessels as well as smaller vessels, these latter comprising what is known as the microcirculation. Diseases of the microcirculation include stroke, dementia, and end stage renal disease to name a few. The microcirculation of the brain (and kidneys) possess a reflex called autoregulation that protects the downstream organ from fluctuations in blood pressure and blood flow. The neurosensory retina of the eye is a forward extension of brain and has a similar microcirculation to that of brain, including the presence of blood retinal barriers and the ability to autoregulate. One of the consequences of very severe hypertension is breakthrough of the autoregulatory reflex with hyperperfusion injury and edema formation. Currently, physicians and scientists have no tools to visualize or measure the human microcirculation or the autoregulatory reflex. SD-OCT is an advanced imaging technology that has a spatial resolution 1000-10,000 times greater than CT or MRI. It is the standard of care for identification and follow-up of structural diseases of the eye. The question this research proposal attempts to answer is whether SD-OCT is able to detect edema or other evidence of structural damage in the eyes in patients in the midst of, or following an episode of very severe hypertension. Pregnant women were chosen to be the focus of this study because: 1) pregnant women are generally young and would be expected to possess a normal microcirculation, 2) the occurrence of new-onset hypertension in pregnancy is high, occurring in 5-10% of all pregnancies, 3) there are established prediction rules that allow one to select and compare women at high- or low-risk of developing hypertension in pregnancy, and finally 4) the spectrum of hypertensive injury in pregnancy ranges from minor elevations in systemic blood pressures to eclampsia, the most severe, life-threatening form of hypertensive injury possible. All this is occurs within a 9-month time window defining human pregnancy. Thus, the investigators are proposing to examine the eyes of women using SD-OCT at low- and high-risk of developing hypertension in pregnancy to determine if, when and how this injury is occurring and its relationship to blood pressures.
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SD-OCT measured change in retinal macular thickness during pregnancy at each gestational period for all study subgroups
Timeframe: At < 20 weeks gestation, from 20 weeks gestation up to before delivery, and at delivery