Retinal and Choroidal Microcirculation in Preeclampsia: An OCTA Study

Preeclampsia is a multisystemic and multifactorial disorder that complicates pregnancy and is characterized by new-onset hypertension after the 20th week of gestation accompanied by proteinuria or systemic findings such as renal dysfunction, hepatic dysfunction, pulmonary edema, thrombocytopenia, or neurological symptoms including headache and visual disturbances. It represents a significant risk factor for maternal and fetal morbidity and mortality. In normal pregnancy, trophoblasts invade and dilate the maternal spiral arteries, thereby increasing uteroplacental blood flow. In preeclampsia, however, inadequate trophoblastic invasion leads to defective placentation, resulting in uteroplacental hypoperfusion and ischemia. The hypoxic and ischemic placenta releases anti-angiogenic mediators into the maternal circulation, which disrupt maternal endothelial function. This endothelial dysfunction results in vasoconstriction, microthrombosis, and increased vascular permeability. Consequently, hypertension, renal and hepatic dysfunction, pulmonary edema, and neurological symptoms may develop in maternal organ systems. The endothelial dysfunction observed in preeclampsia can also affect the microvascular structures of the eye, leading to circulatory disturbances at the level of the retina and choroid. Disruption of endothelial integrity, together with vasospasm and microthrombus formation, may cause reduced perfusion in the retinal and choroidal microcirculation, forming the basis of the ophthalmic manifestations of preeclampsia. Clinically, this condition may present with visual disturbances, blurred vision, scotomas, retinal edema, and choroidal thickening. These microvascular changes can be evaluated noninvasively in outpatient settings using Optical Coherence Tomography (OCT) and Optical Coherence Tomography Angiography (OCTA). OCT and OCTA allow high-resolution imaging of retinal and choroidal structures and enable quantitative assessment of vascular parameters such as vessel density, the size of the foveal avascular zone (FAZ), and choriocapillaris flow voids. Through these techniques, microvascular hypoperfusion, loss of vascular integrity, and ischemic areas caused by endothelial damage associated with preeclampsia can be objectively identified. The aim of this study is to evaluate ocular vascular changes associated with preeclampsia using OCT and OCTA

Inclusion Criteria: \- Female participants aged 18-45 years. Willingness to participate in the study and provision of written informed consent. Absence of ocular media opacities that could interfere with Optical Coherence Tomography (OCT) or Optical Coherence Tomography Angiography (OCTA) imaging (e.g., dense cataract or vitreous hemorrhage). No history of previous ocular surgery. No high refractive error (refractive error greater than ±6 diopters). Singleton pregnancy for participants in the pregnant groups. Preeclampsia group: Diagnosis of preeclampsia after the 20th week of gestation according to established clinical criteria. No history of chronic hypertension, diabetes mellitus, chronic kidney disease, retinopathy or other ocular diseases, systemic vasculitis, or collagen vascular disease prior to pregnancy. Healthy pregnant control group: Healthy pregnancy without preeclampsia or hypertensive disorders of pregnancy. No history of hypertension, diabetes mellitus, chronic kidney disease, retinopathy or other ocular diseases, systemic vasculitis, or collagen vascular disease. Healthy non-pregnant control group: Healthy non-pregnant women without a history of hypertension, diabetes mellitus, chronic kidney disease, retinopathy or other ocular diseases, systemic vasculitis, or collagen vascular disease. Exclusion Criteria: \- History of chronic hypertension prior to pregnancy. Diagnosis of diabetes mellitus (DM) or gestational diabetes mellitus (GDM). Presence of chronic kidney disease. History of retinopathy or other ocular diseases, including glaucoma, uveitis, retinal detachment, or macular pathology. Multiple pregnancy (twin pregnancy or higher-order gestation). History of systemic vasculitis or collagen vascular disease. History of previous ocular surgery. Presence of high refractive error (greater than ±6 diopters). Poor image quality preventing reliable analysis of Optical Coherence Tomography (OCT) or Optical Coherence Tomography Angiography (OCTA) images. Failure to provide written informed consent. Age below 18 years or above 45 years.