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Retinal diseases include any condition that involves the retina. This is the part of the eye that converts optical information into nervous signals that travel to the brain, resulting in the formation of images. Retinal abnormalities can result from genetic conditions, injuries, and chronic diseases and processes that produce effects throughout the body, including in the eyes over periods of time much longer than the duration of pregnancy. However, certain retinal conditions are associated with pregnancy in the sense that changes in hormones, immunological function, metabolism, and blood circulation can exacerbate, trigger, or alter the retinal effects. Of the retinal conditions that pregnancy can affect, the main one is called diabetic retinopathy. This is a condition resulting from damage to blood vessels that occurs in people with uncontrolled diabetes. In particular, diabetes retinopathy involves diabetic damage to the blood vessels of the retina itself.
Pregnancy also can trigger a high blood pressure condition that causes retina disease by harming retinal blood vessels. High blood pressure related to pregnancy also can cause retinal detachment and various, less common conditions involving the retina and its arteries and veins. In the case of retinal problems caused by high blood pressure, this can happen in women with gestational hypertension (high blood pressure resulting from pregnancy), but also in pregnancy complications that include high blood pressure together with additional problems, namely preeclampsia, eclampsia, and HELLP syndrome. In its worse form, HELLP syndrome includes a clotting and bleeding complication called disseminated intravascular coagulopathy, which also can damage the retina. Women who are pregnant, or who have delivered recently, comprise a large portion of patients with another bleeding disorder called thrombotic thrombocytopenic purpura, which can cause retinal damage as well. Additionally, the retina can be damaged by a complication called amniotic fluid embolism, but this complication is rare and often is fatal, so it’s not a major contributor to retinal disease in pregnancy.
Retinal diseases typically are diagnosed by an ophthalmologist viewing the retina and its blood vessels with a device called a slit lamp. A characteristic common among many retinal diseases is that retinal damage stimulates the growth of new blood vessels. This is the body’s attempt to supply needed oxygen and nutrients to damaged tissue, but the process actually accelerates the deterioration of vision, because it is not a healthy kind of blood vessel growth. Because the blood vessel growth is stimulated by a protein called vascular endothelial growth factor (VEGF), one treatment approach for various types of retinal disease are medicines that act against VEGF. Such medicines include bevacizumab. This is an antibody developed specifically to block the actions of VEGF. An ophthalmologist must inject the medicine into the vitreous humor, the transparent, gel-like material between the lens and the retina. This is called intravitreal injection. The ophthalmologist performs the injection through the sclera, the white part of the eyeball, after the eye has been treated with anesthetic and antiseptic agents. It sounds scary, but ophthalmologists who perform this treatment are very good at it and the anesthesia prevents you from feeling any pain. Such injections must be administered every few weeks to months, but they are very effective in preventing blindness. There is concern, however, that medicines that work against VEGF could be dangerous to an embryo or fetus. This is because VEGF is important in the creation of blood vessels during embryonic and fetal life. Additionally, studies showing anti-VEGF agents causing birth defects in laboratory animals back up the concerns. There also is concern about women receiving these drugs who are breastfeeding. Since the drugs are injected into the eye and not the blood, however, and since there is no clear human evidence of problems, it is not known for sure that the treatment is unsafe in pregnancy or nursing.
Another category of drugs that can be given by intravitreal injection is corticosteroids. Steroids present no major risk to the fetus or embryo and are helpful in reducing swelling that contributes to retina damage in diabetic retinopathy and other retinal conditions. This is not the preferred drug category, however, because the steroids also increase the pressure inside the eye, which can lead to glaucoma and promote the development of cataracts. Given these considerations, pregnant women with retinal diseases may be encouraged to opt for non-drug treatments, such as a treatment called laser photocoagulation.