Preeclampsia is a hypertensive disorder unique to pregnancy, typically developing after 20 weeks of gestation. It remains a leading cause of maternal and perinatal morbidity worldwide. This condition is characterized by high blood pressure, often accompanied by signs of organ damage, including the kidneys, liver, and brain. Vision changes are significant indicators of the condition’s severity, affecting up to 40% of patients with preeclampsia. The eye is a highly vascular organ, making it particularly susceptible to the systemic vascular dysfunction and high blood pressure that define this disorder. Ocular disturbances often prompt the medical evaluation that leads to diagnosis and timely intervention.
Common Visual Disturbances
The primary visual symptom in patients with preeclampsia is blurred vision, ranging from slight haziness to reduced visual acuity. This blurring should never be dismissed in the presence of elevated blood pressure, even though it may be incorrectly attributed to normal pregnancy fluid shifts. Patients may also experience scotomas (blind spots or areas of partial vision loss). These visual field defects can appear suddenly and are an important sign of underlying retinal or neurological involvement.
Another common complaint is photopsia, involving flashing lights, shimmering spots, or floaters. These phenomena result from abnormal stimulation of the light-sensitive retina due to vascular changes. Less frequently, individuals may experience diplopia (double vision), suggesting complex neurological or muscular involvement. Although these symptoms are often transient, they signal a need for urgent medical assessment as they can precede more severe complications.
How Preeclampsia Affects Eye Structure
The systemic pathophysiology of preeclampsia, particularly the widespread endothelial damage and high blood pressure, directly affects the delicate vascular network of the eye. The initial change is vasospasm, where small retinal arteries constrict and narrow in response to high blood pressure. This narrowing reduces blood flow to the back of the eye, which can lead to localized areas of retinal tissue ischemia, or lack of oxygen.
The damaged endothelium becomes leaky, allowing fluid and protein to seep into the surrounding tissue. This fluid leakage (edema) can cause the retina to swell (retinal edema), and may also lead to swelling of the optic nerve head (papilledema). These fluid shifts and swelling distort the light path and the retinal structure, which directly accounts for the blurred vision and visual field defects experienced by the patient.
A more severe complication is serous retinal detachment (SRD), occurring when excessive fluid accumulates between the neurosensory retina and the underlying tissue. This fluid buildup causes the retina to lift away from its normal position, leading to significant and sudden vision loss. SRD is often linked to localized areas of ischemia in the choroid, the layer of blood vessels beneath the retina, due to acute and severe hypertension. Although SRD can be alarming, the prognosis is favorable; the retina often reattaches and vision returns to normal once blood pressure is controlled and the fluid reabsorbs, typically after delivery.
When Vision Changes Require Immediate Attention
Any new or worsening visual disturbance during pregnancy or the postpartum period should be treated as a medical emergency. The most alarming warning signs include the sudden onset of vision loss or a significant, persistent increase in the number of flashing lights or blind spots. A particularly dangerous symptom is temporary complete vision loss, known as amaurosis fugax or cortical blindness, which is linked to swelling in the occipital cortex of the brain.
These severe visual changes are often precursors to eclampsia, a life-threatening complication defined by the occurrence of seizures. The underlying cerebral edema and vascular changes that cause the severe visual symptoms are the same processes that can trigger a seizure. Vision changes accompanied by a severe, persistent headache that does not improve with over-the-counter pain relievers, or pain in the upper right side of the abdomen, should trigger an immediate trip to the emergency department.
Immediate medical intervention focuses on stabilizing the patient and preventing seizures, primarily through aggressive blood pressure control and the administration of magnesium sulfate. Magnesium sulfate is given intravenously to act as a neuroprotectant and prevent the progression to eclampsia. Depending on the gestational age and the severity of the mother’s condition, the ultimate treatment for preeclampsia is often the delivery of the baby, which removes the source of the underlying placental disorder. Prompt reporting of any visual symptom ensures that the healthcare team can initiate this cascade of protective treatments swiftly, safeguarding the health of both the mother and the fetus.