Ординатура / Офтальмология / Английские материалы / Clinical Medicine in Optometric Practice_Muchnick_2007

Pregnancy can induce radical changes to the eye. The optometrist must take care not to harm the mother or fetus when performing an ophthalmic examination or when treating the mother’s eye disease. Physiological changes may occur to the tear layer, cornea, and the ocular tissues involved in intraocular pressure maintenance. Pathological conditions associated with or exacerbated by pregnancy include retinal and neurologic diseases. Topical medications may induce systemic manifestations in the mother-to-be and may potentially threaten the pregnancy or the fetus. This chapter reviews the alterations of the normal ocular physiology and the eye diseases associated with

pregnancy.

DOCTOR-PATIENT INTERPERSONAL COMMUNICATION

One of the most challenging aspects of taking a history is the attempt to uncover whether a woman is pregnant. The asking of such a question at first seems fairly straightforward, however, experience will confirm that offense might be taken if the patient feels that the questioner is implying that she is obese. Nonetheless, the question must be posed to all patients who are about to undergo any optometric examination and treatment with topical medications, because these can have seri-

ous medical ramifications to the mother and fetus. In addition, the examiner will wish to display appropriate sensitivity when raising this question, because the patient may be have issues concerning weight, the loss of a fetus or child, or the inability to conceive.

One way to preserve the effectiveness of the doctorpatient bond without risking offense is to have the patient fill out a checklist that includes a question about pregnancy. This method avoids the patient thinking that she is being singled out by the doctor and asked about pregnancy because of her appearance. Despite a woman’s age, she must be asked about pregnancy, and the checklist history avoids embarrassment when the very young teenager or the senior citizen is being examined.

One problem with the checklist is that it is impersonal, and does not strengthen the doctor-patient bond. Thus, another effective technique is to ask the female patient if she has any known medical condition, such as pregnancy, for which she is seeking medical care. By wrapping the central issue of pregnancy in the guise of other medical care, the patient realizes that the question of pregnancy is not being raised because of her personal appearance.

The examiner must determine whether the pregnant patient is smoking or using drugs and counsel against such behavior during pregnancy.

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PHYSIOLOGICAL ALTERATIONS Changes in the Tear Layer

Complaints of dry eye may occur during pregnancy, particularly in contact lens-wearing patients. Alterations in the normal tear structure are most likely the result of the dramatic hormonal changes that occur during this period of time. Topical staining may reveal stippling of the corneal epithelium, or, in more serious cases, a florid superficial punctate keratopathy. This condition of keratitis sicca is temporary, and should resolve after delivery, although it may persist during nursing. Artificial tear substitutes may reduce the symptomology of the sicca condition, but oral flax seed or fish oil capsules for the control of the dry eye should only be used with her physician’s approval. The dry eye condition makes the use of contact lenses problematic, and may force the mother-to-be to reduce or discontinue wear. This situation can be a significant psychological challenge, because she may already be experiencing severe stress and anxiety. It is important to stress that the condition is temporary and contact lens wear may resume after delivery or when nursing has ended. Excess mucus production may also occur during pregnancy, causing transient blurring of vision. This condition resolves after delivery.

Changes in the Cornea

Pregnancy affects the cornea in three ways: it thickens, changes shape, and decreases in sensitivity. All these changes can alter visual acuity, refractive error, and contact lens wear. During pregnancy the cornea tends to thicken, most likely because of a generalized systemic edema that induces corneal uptake of fluid. This corneal edema reduces corneal sensitivity and can adversely affect contact lens wear. The thickened cornea is associated with an increase in corneal curvature, and these factors change the refractive error of the patient so that the patient may experience reduced visual acuity with her present spectacles or contact lenses. The fitting of contact lenses should be avoided until 1 month after delivery or after nursing has ceased. In addition to the above, a higher rate of pigmentary deposit in the shape of a Krukenberg’s spindle has been observed in pregnant women. This condition may be the result of hormonal changes that cause pigmentary migration to the aqueous with eventual deposition onto the corneal endothelium.

Changes in Accommodation

A reduction in accommodation during pregnancy may occur caused by a thickening of the ciliary body because of fluid retention. A low-plus spectacle for near work may help the patient during this period. Accommoda-

tion usually returns to normal after delivery, but may be permanently reduced in presbyopic individuals.

Changes in Intraocular Pressure Maintenance

Hormonal changes increase the facility of the uveoscleral outflow mechanism and thus decrease intraocular pressure during pregnancy. The reduced intraocular pressure decreases in the second half of the pregnancy and may persist for several months after delivery. Another explanation for the reduced intraocular pressure is a decrease in the episcleral venous pressure.

PATHOLOGICAL CONDITIONS Dermatological Disease

Chloasma

Typically a brown, blotchy, and flat hyperpigmentation, this skin change is a painless hypermelanosis of the skin around the eyelids. Known as the “mask of pregnancy,” chloasma usually fades within a few months after delivery. Chloasma is most likely the result of high estrogen and progesterone levels.

Spider Angiomas

These reddish-purple spidery superepithelial blood vessel growths are painless and typically occur on the face and upper body. These growths are most likely the result of increased estrogen levels.

Eyelid Disease

Ptosis

Most cases of pregnancy-related ptosis of the upper lid are unilateral and related to fluid-retention or hormonal effects. Sleeping in a propped-up position will help reduce morning lid edema. Nonetheless, the spontaneous appearance of ptosis in any patient should elicit an immediate investigation to rule out a serious underlying neurologic entity. For example, Horner’s syndrome may be more likely in the pregnant woman because of epidural analgesia used in delivery. Horner’s syndrome and ptosis usually resolve within hours postpartum.

Retinal Disease

Pregnancy-Induced Hypertension

Typified by proteinuria, systemic hypertension, and peripheral edema, pregnancy-induced hypertension (PIH) may occur in the second trimester of pregnancy, usually after the 20th week. Once known as preeclampsia, PIH occurs in as many as 5% of healthy women during their first pregnancy. It is also more

common in multifetal pregnancy, very young or old maternal age, and in mothers who have vascular disease. This condition is serious because it can induce placental vascular insufficiency, thus threatening the viability of the fetus, and can even cause the death of the mother. PIH usually occurs spontaneously, but it may be brought about by medications. Topical medications such as epinephrine drops used for dilation of the pupil may induce PIH if absorbed systemically. PIH is diagnosed quickly by very elevated blood pressure readings in a pregnant woman. Extremely high systemic blood pressure can be associated with convulsions and is known as eclampsia. These PIHassociated convulsions usually occur later in the pregnancy and have an even more ominous prognosis than preeclampsia. Visual changes that include diplopia, scotomas, and blurred vision occur in 25% of preeclamptic women and 50% of eclamptic women. Retinal findings in PIH appear similar to hypertensive retinopathy and may include serous retinal detachments, retinal vascular occlusion, and yellowish opaque lesions of the retinal pigment epithelium. Ischemic optic neuropathy has occurred as a result of severe preeclampsia. Approximately 10% of women with PIH develop hemolysis, elevated liver enzymes, and low platelet count. Known as the HELLP syndrome, this PIH-related disorder may be associated with cortical blindness, vitreous hemorrhage, and serous retinal detachments. The visual findings usually resolve with swift and appropriate medical intervention. Because medications may induce PIH, topical epinephrine eye drops should be avoided when dilating the pupils of the pregnant patient. If such drops are necessary, as with the patient who complains of flashes and floaters or who requires intraocular surgery, then punctual occlusion for 1 to 2 minutes after insertion of the drops is recommended. This technique will minimize systemic absorption and reduce the risk of inducing PIH. Systemic management of PIH includes systemic blood pressure control, electrolyte imbalance control, and immediate delivery of the fetus if fetal maturity is appropriate.

Diabetic Retinopathy

According to the Diabetes in Early Pregnancy study (DIEP), diabetic retinopathy is most likely to progress in women with the poorest metabolic control over their serum glucose early in their pregnancy. In the study, this poor control was reflected in women with the best reduction in their HbA1c test. The dramatic improvement in the glycosylated hemoglobin ratio in these patients demonstrates that they had poor glucose control before pregnancy. The study found that the poorer the metabolic control of serum glucose during pregnancy, the faster the diabetic retinopathy progressed.

Therefore, pregnancy worsens the course of diabetic retinopathy, sometimes to a significant degree. The DIEP study found that the state of diabetic retinopathy at the time of conception greatly influences the degree to which the retinopathy advances during pregnancy. For example, minimal baseline retinopathy at the time of conception, with just a few dot hemorrhages and less than 10 microaneurysms with no exudates, advanced to only an increase in microaneurysms in 8% to 21% of diabetic eyes. These cases of minimal baseline retinopathy at the time of conception never progressed to proliferative disease. In cases of mild diabetic retinopathy at the time of conception, however, 6% of cases did progress to the proliferative stage. Furthermore, in cases of moderate retinopathy at the time of conception, 29% of cases progressed to the proliferative stage. Axer-Seigel and others report that 26% of insulindependent diabetes mellitus patients with no retinopathy at conception developed mild nonproliferative diabetic retinopathy during the course of the pregnancy. Patients who develop gestational diabetes during pregnancy, however, are not at risk for diabetic retinopathy (although they do show an increased risk of developing diabetes mellitus later in life). Pregnant women who develop clinically significant diabetic macular edema (CSDME) usually have the edema resolve postpartum with improvement of their visual acuity. Patients with proliferative disease should have it treated by panretinal photocoagulation (PRP) before conception. A 26% lower rate of progression of diabetic retinopathy exists among women whose proliferative disease was treated versus those who did not receive such treatment. Although proliferative disease may regress after delivery, PRP should be used before conception or early in the pregnancy, because it reduces the risk of vitreous hemorrhage during delivery.

Central Serous Chorioretinopathy

Pregnancy-related hormonal changes may induce the exudation of fluid from capillaries under the macula. The fluid causes a neurosensory detachment of the macula with a resultant mild-to-moderate reduction of visual acuity. Usually the patient complains of a unilateral blurring of vision. A fundus examination may not be revealing as the sensory detachment can be subtle, but grayish-white subretinal exudates may be visualized in as many as 90% of pregnant women with central serous chorioretinopathy (CSC) within the area of the detachment. A photostress test usually reveals a delayed regeneration of photoreceptors that have been bleached out by intense light on the side with the CSC. Diagnostic fluorescein angiography is not necessary. Usually the detachment resolves within a few months after delivery with return of baseline visual acuity. Half of all cases of CSC during pregnancy occur in the third trimester.

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Thrombotic Thrombocytopenic Purpura

A rare disease of unknown etiology, thrombotic thrombocytopenic purpura (TTP) is a usually fatal disease that occurs during pregnancy. TTP is characterized by hemolytic anemia caused by platelet destruction and consequential hemorrhaging. The patient may exhibit fever and malaise. Because subretinal fluid exudation may exist that results in complaints of blurred vision, the patient may seek out an eye specialist before seeing her physician. Ophthalmoscopy may reveal disc edema and retinal hemorrhages. Diplopia may result from paresis of the extraocular muscles. Any pregnant patient who is seen with diplopia or retinal hemorrhages is at risk for TTP and should be referred to her physician immediately for a serum analysis.

Disseminated Intravascular Coagulation

Unlike TTP, which causes an anemia secondary to platelet destruction, disseminated intravascular coagulation is a syndrome characterized by the development of fibrin clots throughout the small blood vessels of the pregnant patient. This condition results from activation of various clotting mechanisms and can cause blood clots to occlude the choriocapillaris of the choroids. This process can result in serous detachment of the retina and blurred vision. This clotting abnormality can be treated, and vision usually returns to normal once the systemic condition is resolved. This widespread thrombus formation is most often associated with complicated abortions, severe preeclampsia, and retained dead fetus.

Neurologic Disease

Pseudotumor Cerebri

Pseudotumor cerebri (PTC) is characterized by an elevation in intracranial pressure in the absence of a mass lesion of the brain. The etiology of PTC is often unknown, although it may be related to infection, obesity, intracranial obstruction, and various medications. Also known as idiopathic intracranial hypertension, the increased pressure gradient of the cerebral spinal fluid (CSF) yields a subtle, typically frontal headache. Mild blurred vision is often an early complaint. The patient may also experience scotoma, neck pain, and sixthnerve palsy. Ophthalmoscopic evaluation typically demonstrates papilledema, with blurring of the disc margins in both eyes. During pregnancy, symptoms of PTC should elicit a concerted effort to confirm the presence of elevated intracranial pressure using MRI, lumbar puncture, CSF analysis, and ophthalmoscopy. PTC does not occur more commonly in pregnant women. The treatment of PTC is complicated in the pregnant woman, because medical intervention aimed at preservation of the visual field and symptomatic

relief must be weighed against possible harm to the fetus. The typical treatment for PTC, weight loss, cannot be attempted during pregnancy. The optometrist must carefully document any visual field loss, and visual fields should be monitored monthly during pregnancy. If visual loss occurs, a short course of oral steroids during a 6-week period should help to prevent permanent field loss and still not harm the fetus. Another treatment for PTC, oral Diamox (acetazolamide), can be used only after 5 months of fetal gestation.

Multiple Sclerosis

Because multiple sclerosis (MS) peaks in women 20 to 40 years old, and occurs twice as often in women as in men, a significant number of pregnant women will have MS. MS is characterized by a demyelination of the nerves that supply the central nervous system. In this condition, loss of the protective myelin sheath that surrounds the nerve occurs, causing a disruption in electrical conduction. Consequently, paresthesia, memory loss, and loss of fine motor movements occur with the visual symptoms of diplopia, nystagmus, blurred vision, and field defects. The diagnosis of MS is made on the basis of magnetic resonance imaging (MRI) evaluation of the white matter of the brain and CSF evaluation. During pregnancy, MS attacks typically decrease and are less severe than normal. Postpartum, however, the attacks increase and are more severe during the first 3 months after delivery. The attacks then tend to stabilize to the rate typical before conception.

Pituitary Adenoma

These often microscopic and asymptomatic tumors of the pituitary gland grow more rapidly and become more symptomatic during pregnancy. Monthly visual fields are required during pregnancy to monitor any deterioration of the visual field. Medical use of bromocriptine (a dopamine agonist) can help tumor regression without adversely affecting the fetus.

Meningioma

This tumor is a slow-growing, well-encapsulated, and typically nonmetastatic lesion that is more common in pregnant women than in the general population. Because it can cause a variety of visual symptoms such as diplopia, blurred vision, and field defects, any pregnant woman with these symptoms should have a visual field and a referral to their obstetrician to rule out meningioma.

Pregnancy-Related Drug Interactions

Diagnostic Agents

The most significant diagnostic topical agent to avoid in the pregnant woman is phenylephrine. This medication, used diagnostically to dilate the pupil (with a

parasympatholytic agent), can exert a vasopressive effect. This in turn can lead to eclampsia and preeclampsia. In cases in which dilation is necessary for retinal evaluation of possible sight-threatening conditions (such as detachment), a 2.5% solution is advisable instead of a 10% solution. The higher concentrated phenylephrine has a greater chance of causing hypertension in the pregnant patient. Dilation of the mother to be is achieved most safely by the use of tropicamide, because both atropine and homatropine have been linked to birth defects, and scopolamine can cause tachycardia in the newborn infant. Topical anesthetics must be used with caution because no studies have been performed on these medications. Fluorescein dye can cause an allergic reaction in sensitive patients, and so should be avoided in pregnancy if possible. Fluorescein dye does cross the placenta and is also present in the breast milk for as long as 72 hours after administration, although no adverse fetal reactions have been observed.

Therapeutic Agents

During the typical 9-month gestation period, the pregnant woman may need topical medication to treat ocular disease. No medication is applied without risk, but the effect on mother and fetus may be minimized by punctal occlusion. If topical medications are necessary, then the following cautions should be understood:

■Phenylephrine. This topical medication may be used for therapeutic purposes in the breaking of posterior synechiae in cases of anterior uveitis. Because it has vasopressive effects, and its use may lead to eclampsia or preeclampsia, punctual occlusion is necessary. In addition, only the 2.5% form should be used in the pregnant patient, because the stronger 10% form has a much greater vasopressive effect. Unfortunately, the 2.5% form does not break synechiae as effectively as its stronger counterpart.

■Topical antibiotics. Topical polymyxin B and erythromycin have not been found to cause fetal damage and appear safe to use to treat bacterial conjunctivitis. Risk to the fetus cannot be ruled out when using any of the fluoroquinolones (such as ciprofloxacin and ofloxacin), because high dosages to test animals resulted in lower birth weight and skeletal abnormalities. Nursing mothers should be cautious not to use any fluoroquinolone, because the systemic form can be excreted through her breast milk.

■Topical antiviral agents. The risk cannot be ruled out when using mediations such as Viroptic (trifluridine), but animal studies have failed to reveal any problems. It is unknown whether Viroptic is excreted in the breast milk, thus the drop should be discontinued before nursing commences.

■Topical steroids. The risk to the fetus cannot be ruled out, and thus topical steroids should only be

used with caution and punctal occlusion. The potential benefits may outweigh the potential risk particularly in cases of severe uveitis. In controlled animal experiments, topical steroids caused cleft lips and palates.

■Glaucoma drugs. Beta-blockers such as Timoptic (timolol maleate) can cause neonatal bradycardia and lowered blood sugar readings, and can occur in the breast milk. These drugs should be avoided during pregnancy, but the American Academy of Pediatrics has approved timolol to be used during lactation. Alphagan (brimonidine), a selective alpha-2 adrenergic agonist, shows no evidence of risk in humans, and is relatively safe to use in pregnancy. Alphagan can reach toxic levels in the breast milk and cause hypertension and apnea in children younger than 2 months, and thus should be used cautiously in lactating patients. The prostaglandins (travoprost [Travatan], bimatoprost [Lumigan], and latanoprost [Xalatan]) are a newer generation of glaucoma medications that have not been adequately studied as of yet. One small study of nine women failed to show any relationship between the use of latanoprost and an adverse outcome of pregnancy. Lactating mothers should use these with caution, because it is unknown whether the prostaglandin medication is excreted in the breast milk. The sulfonamides, such as the carbonic anhydrase

inhibitors (CAI), medications that include acetazolamide (Diamox) and methazolamide (Neptazane), are potentially fetal-toxic and should be avoided during pregnancy. This warning may apply to topical CAI agents as well.

In general, all topical diagnostic and therapeutic agents should be avoided whenever possible during pregnancy and lactation.

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Schecter S: How to care for mothers-to-be, Review of Optometry March 15, pp 63-70, 2002.

Sheth BP, Mieler W: Ocular complications of pregnancy, Curr Opin Ophthalmol 12:455-463, 2001.

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