Physiologic Ocular Changes Occurring During Pregnancy
Does pregnancy affect eyes in any way? What are the physiological changes occurring in eyes during pregnancy ?
Corneal sensitivity has been found to be decreased in most pregnant women, where a majority of changes occur in the third trimester and then reverse in postpartum. One potential mechanism may be related to the slight increase in corneal thickness that may develop from corneal edema.
Furthermore, an increase in corneal curvature and steepening may also occur. These changes have been reported to develop even in the postpartum period during breastfeeding. However, corneal curvature is reversible upon cessation of breastfeeding.
Contact lens intolerance may occur during pregnancy as a result of a change in corneal curvature, increased corneal thickness/edema, or an altered tear film. In any case, it is recommended that one should wait several weeks postpartum before prescribing to a new refraction. Additionally, decreased or transient loss of accommodation may occur during pregnancy or within the postpartum period.
Newly developed Krukenberg spindles have been observed early in pregnancy. The mechanism presumably is related to hormonal changes (eg, low progesterone levels). However, by the third trimester, an increase in progesterone and aqueous outflow often result in decreased or absence of Krukenberg spindles.
A decrease in intraocular pressure has been shown to occur during pregnancy and often persists for several months postpartum. Various mechanisms have been described for this observation: an increase in aqueous outflow; a decrease in systemic vascular resistance, leading to decreased episcleral venous pressure; generalized increased tissue elasticity, leading to decreased scleral rigidity; and generalized acidemia during pregnancy.
This decrease in intraocular pressure may have implications for pregnant women with preexisting glaucoma, since improvement of the disease during pregnancy has been reported in a few cases.
Visual field changes
Wide speculation exists about the degree and mechanism of visual field changes that may occur in pregnant women. Types of field loss may include bitemporal loss, concentric constriction, and enlarged blind spots. Proposed mechanisms are equally diverse and include changes to the pituitary gland that may affect the optic chiasm. These asymptomatic visual field changes were shown to be completely reversible postpartum. However, pregnant women with symptomatic visual field loss warrant further investigations.
A decrease in conjunctival capillaries and an increase in the granularity of conjunctival venules have been reported to occur; each being reversible during the postpartum period.
Another common external result of pregnancy is changes to the skin called chloasma. Due to increased hormone levels (ie, progesterone), some pregnant women experience increased pigmentation around the eyes and cheeks. The pigmentation changes tend to fade slowly postpartum.