Ophthalmologists, neuro-ophthalmologists, and optometrists should understand the impact pregnancy can have on the eye, according to Kathleen B. Digre, MD.
“Pregnancy is really a window of opportunity during which 2 people are cared for simultaneously, as well as a window into the patient’s future health. The latter began to become apparent during the past 20 years,” she commented. Digre, a neuro-ophthalmologist, is Distinguished Professor of Neurology Emerita, professor of ophthalmology, adjunct professor of obstetrics and gynecology, Moran Eye Center, University of Utah, Salt Lake City.
Previously, she noted, clinicians paid attention to a pregnant patient’s eyes only when something went wrong. More recent studies have focused on the ocular effects of pregnancy, and understanding these potential effects is important for clinicians seeing patients in the chair.
Physiologic effects of pregnancy
Digre described pregnancy as a stress test on a woman’s cardiovascular, immune, and coagulation systems, the major ones affected during a normal pregnancy.1-3
“Basic physiologic changes occur. Blood volume, cardiac output, and coagulation factors change during pregnancy. The immune system changes to avoid expelling the fetus. These are the important adjustments that make pregnancy especially important for all women and for women’s ocular health,” she said.
Specifically, according to Digre, the blood volume and cardiac output can increase by 30% to 50% by term. Cardiac output can increase even further during labor. Hypercoagulability is characterized by elevated plasminogen and fibrinogen levels; elevated levels of factors I, V, VII, IX, and X; and decreased fibrinolytic activity. Hyperplasia of smooth muscle and fragmentation of the reticular fibers within the blood vessel walls are seen. Extracellular fluid can increase by 2 L by term, Digre reported.
Ocular changes during normal pregnancy
Benign physiologic changes generally resolve shortly after delivery or nursing. These include refractive changes resulting from increased blood volume and fluid retention that cause progesterone-mediated fluid buildup in or behind the eye, resulting in corneal thickness and curvature changes toward myopia.4,5
Microvascular changes can develop in the retina of women with obesity,6 and the macula’s vascular density can increase.7 Hormonal changes can reduce tear production, resulting in dry eye and making contact lens wear uncomfortable during the third trimester. Dry eye affects almost 80% of patients during the third trimester,8,9 Digre related.
IOP can decrease by approximately 10% during the second half of pregnancy, but the retina and optic nerve generally are spared from alterations.5,10-12
Physiologic changes also can occur in the brain. Studies have documented slight decreases in brain size, generally related to hormones or fluid changes.13,14 Numerous biochemical/hormonal changes in the brain in pregnancy and post partum prepare women for motherhood.15 The pituitary gland increases in size, and sleep is dysregulated late in pregnancy.16-18
Migraine develops often in pregnancy and more often in women who are and are not pregnant, compared with men; 20% of all women have migraines.10 During pregnancy, women can experience their first migraine aura, which must be differentiated from preeclampsia or other disorders by measuring blood pressure. Aura will be a self-limiting event that resolves with time; in contrast, preeclampsia and eclampsia are characterized by consistent headache and elevated blood pressure. “Ophthalmologists will see migraine in clinic every day, but pregnant women seen in ophthalmology with headache and visual changes can benefit from a blood pressure check,” Digre stated.
Changes during a complicated pregnancy
Gestational diabetes is a major concern because retinopathy can worsen during pregnancy, depending on hypertension and diabetes control; affected patients require frequent examinations.
Retinopathy occurs when high glucose levels damage the blood vessels in the retina, potentially leading to background hemorrhaging, microaneurysms, and rapid loss of visual clarity.19
Message for eye care clinicians
Digre advises making the following considerations part of daily practice when examining pregnant patients:
- Make the correct diagnosis—use the necessary tests, including blood pressure measurements and optical coherence tomography.
- Consider pregnancy-related conditions—know what they are.
- Add pregnancy and pregnancy complications in the history—if a woman has a history of preeclampsia, hypertension later in life may be diagnosed.
- Discuss potential pregnancy in all women of childbearing age.
- What is best for the mother usually will be best for the baby.
Also of concern are preeclampsia, eclampsia, and HELLP syndrome (characterized by Hemolysis [destruction of red blood cells], Elevated Liver enzymes [liver damage], and Low Platelet count [clotting problems], often associated with preeclampsia).19,20 “These are related to a whole host of visual problems, such as blurry vision, photopsias in the visual field, seizures, and even stroke,” Digre emphasized.
When a patient presents with blurred vision or headache, the eye care clinician must measure the blood pressure to identify preeclampsia, a pregnancy-specific condition, she advised.
Ocular complications affect approximately 25% to 33% of women with preeclampsia and up to 50% of those with eclampsia, Digre said. The resulting high blood pressure can cause severe vascular changes in the eye: HELLP syndrome is characterized by hemolysis, elevated liver enzymes, and low platelet counts.
Other ocular complications include preeclamptic retinopathy characterized by arteriolar narrowing, retinal hemorrhages, swelling, and cotton-wool spots; serous retinal detachment, in which fluid accumulates under the retina, and resultant localized visual field defects or blurred vision (in up to 10% of patients with eclampsia); and associated neurologic changes, such as ischemic optic neuropathy, papilledema, and occipital cortex involvement (which can cause temporary cortical blindness).21
Pregnant women, particularly those experiencing stress or elevated blood pressure, are at a higher risk for central serous chorioretinopathy. Fluid leakage occurs under the central retina, causing a gray or blurred spot in the central vision, distorted shapes (metamorphopsia), or reduced color vibrancy.22
