Ocular associations in pregnancy

At the completion of this article, the reader should be able to improve their understanding of ocular associations in pregnancy. Including:

• Recognise pregnancy-related physiological ocular changes
• Understand the rationale for revising standard clinical protocols when treating a pregnant patient
• Understand how pregnancy can modify pre-existing ocular pathologies
• Identify ophthalmic conditions due to pregnancy complications which necessitate referral

Profound systemic and ocular changes can take place during pregnancy, making it vital for clinicians to understand how these changes can affect the health and vision of expectant patients. As A/Prof SUDHA CUGATI and Prof CELIA CHEN point out, the practitioner’s duty is heightened because they have two patients to think of.

A/Prof Sudha Cugati
MBBS, MS, PhD, FRANZCO
Consultant Ophthalmologist, Modbury Hospital, South Australia

Prof Celia Chen
MBBS, MPH, PhD, FRANZCO
Academic Professor, Flinders University
Clinical Professor, University of South Australia

The eyes can undergo physiological and pathological changes in pregnancy. Some changes exacerbate pre-existing eye conditions while other conditions manifest for the first time during pregnancy. Early recognition and management are essential to prevent sight-threatening complications. 

While treating a pregnant patient, it’s essential to remember that you are dealing with two people – the pregnant woman and the foetus. In addition, some obstetric complications can be associated with ophthalmic signs, so prompt recognition of these eye findings may be lifesaving for both the mother and the foetus. 

The aim of this article is to improve awareness of the potential ocular complications in pregnancy, to help recognise the indications for prompt referral to a specialist to preserve sight, and maintain maternal and foetal safety. The safety of the use of common ophthalmological medications will also be discussed. 

Physiological ocular changes in pregnancy

• Eyelids

Hormonal changes in pregnancy can result in melasma, an increased pigmentation around the eyes and cheeks. It normally does not require any active intervention and tends to fade slowly after pregnancy. 

• Cornea

During the second and third trimesters of pregnancy, corneal thickness can increase up to 16 microns and curvature can increase by an average of 1 diopter sphere resulting in refractive changes which returns to normal soon after delivery. 

Corneal sensitivity can also decrease during pregnancy and can return to normal by two months postpartum. Reduction in corneal sensitivity can increase the risk of infections. There is also an increased prevalence of dry eyes in pregnancy which increases with gestational age.² 

Refractive changes and issues during pregnancy³

• Myopia in Pregnancy

Myopic shift in the lens results from increased lens curvature in pregnancy, resulting in a change in refraction. In addition, a temporary loss of accommodation can be seen in the immediate post-partum period. These lenticular changes also indicate that new glasses or refractive surgeries should be withheld during pregnancy. Patients who are high myopes are not at an increased risk of retinal detachment during delivery and spontaneous vaginal delivery is not contraindicated in these patients. 

• Contact lens intolerance

Many pregnant women develop contact lens intolerance which could be explained to be due to the changes in corneal curvature and thickness, as well as dry eyes. It is advisable not to prescribe new contact lenses during pregnancy. 

• Refractive eye surgery and pregnancy

Due to the changes in the corneal curvature and myopic shift, it is recommended that refractive surgery be avoided during pregnancy and until after the refraction is stable postpartum. 

A. Pre-existing eye condition modified during pregnancy 

• Diabetic Retinopathy (DR)

Progression of DR can be seen in the second and third trimester of pregnancy in patients with Type 1 and Type 2 Diabetes (Figure 1 A and 1 B). 

The degree of DR at the start of pregnancy, glycosylated haemoglobin (HbA1C) control, duration of diabetes and presence of hypertension are known risk factors for worsening of DR in pregnancy. 

Diabetic macular oedema (DME), resulting in severe vision loss, may develop during pregnancy. Improvement and regression of DR tend to occur postpartum. 

Ocular examination is recommended before conception and during the first trimester of pregnancy.⁴ 

Appropriate and prompt referral should be made to an ophthalmologist if there is a progression of DR or if severe DR is noted at the onset. Laser photocoagulation is recommended prior to pregnancy in patients with severe non proliferative diabetic retinopathy.⁵ 

In patients with DME, intravitreal steroids may be a safer alternative to intravitreal anti-vascular endothelial growth factor (VEGF), the safety of these agents is not established in pregnancy.  

Patients with gestational diabetes are usually checked at 28 weeks of gestation. The risk of developing DR in patients with gestational diabetes is less than 1%. Ophthalmological assessment is usually not essential in these patients. 

• Glaucoma

Pregnancy is protective against glaucoma. Increased progesterone level during pregnancy causes increased the uveoscleral outflow, thus reducing the intraocular pressure (IOP). The level of female sex hormones during pregnancy are also neuroprotective to the optic nerve. 

These physiological effects and IOP return to baseline three months postpartum. In pregnant patients with glaucoma, the IOP may decrease, thus requiring fewer glaucoma drops.⁶ Certain IOP-lowering medications are contraindicated in pregnancy which will be discussed later in the article. 

• Idiopathic Intracranial hypertension (IIH)

In a patient with pre-existing IIH, weight gain during pregnancy may worsen the intracranial hypertension. Therefore, regular monitoring, usually at the first trimester, at the end of the second trimester and the six weeks postpartum is recommended. If a significant increase in optic nerve swelling is noted with increase in OCT retinal nerve fiber layer thickness, then there are measures that may help to temporise and lower the intracranial pressure with lumbar puncture or lumbar drain.

The presence of IIH is not a contraindication to normal delivery. 

The usual medication used to treat IIH is acetazolamide, a carbonic anhydrase inhibitor. It is a class B2 medication – drugs which have been taken by only a limited number of pregnant women. There are reports of teratogenic effect with midline cleft syndrome in animal models but not human. In general, most patients prefer to be off the medication when trying to conceive. However, if required, acetazolamide has been demonstrated to be relatively safe in pregnancy and can be used in patients with IIH. These should be in consultation with the treating neuro-ophthalmologist and obstetrician.

• Meningiomas

Meningiomas, a typically slow growing tumor, can have an accelerated growth in pregnancy due to increasing estrogen and progesterone levels and vascular endothelial growth factors. Pregnant patients with known meningioma in the sellar and suprasellar region that may result in compressive optic neuropathy, should therefore be referred and monitored to a neuro-ophthalmologists with ongoing follow-up.

B. Pathological conditions occurring for the first time in pregnancy

• Central serous chorioretinopathy (CSCR) 

Pregnancy increases the risk of CSCR due to the increased cortisol levels and other hormonal changes. Patients often note mild vision blurring and colour changes. Examination usually shows a hyperopic shift due to elevation of the macula and OCT can confirm the CSCR changes (Figure 2). It can occur in all trimesters of pregnancy and can resolve spontaneously, usually over 6-8 weeks or by the time of postpartum.⁷ CSCR can recur in subsequent pregnancy. It is important to educate the patients about the natural course of the disease. 

• Uveal melanoma

Ocular melanoma is more prevalent and tends to progress rapidly in pregnant women compared with non-pregnant women.⁸ The mechanism of tumour growth during pregnancy is unclear as hormonal correlation in pathophysiology of melanoma has not yet been established. Patients with known melanoma or newly detected uveal melanoma should prompt a referral to an ophthalmologist with interest and expertise in ocular oncology.

C. Ophthalmic associations due to complications in pregnancy

The following conditions in pregnancy can be associated with visual symptoms. It is important to recognise these conditions and an appropriate referral should be made to the ophthalmologists. 

• Preeclampsia and Eclampsia

Preeclampsia causes severe arteriolar spasm due to vasospasm and increased resistance to blood flow and generalised constriction of retinal arterioles. The visual system is affected in approximately 25% of patients with preeclampsia and 50% of patients with eclampsia. Patients can present with symptoms of blurred vision, visual field defects and diplopia.

Fundus findings in preeclampsia may include retinal arteriole narrowing, tortuosity, retinal haemorrhage, and optic nerve swelling (Figure 3). Occasionally patients can present with acute vision loss due to serous retinal detachment (RD) or cortical blindness. Presence of these changes in pregnancy warrants urgent referral to her obstetrician for blood pressure monitoring and management.  

• Disseminated intravascular coagulopathy (DIC) 

DIC, a major emergency in pregnancy, is caused by the disruption of coagulation pathways (intrinsic and extrinsic), resulting in formation of small thrombi in small vessels generalised or localised in the body. 

Patients with DIC can present with complaints of blurred vision, visual field defects or metamorphopsia, either due to central choroidopathy or serous RD. A characteristic of these presentations is a bilateral involvement. These women require prompt management by the obstetrician to prevent systemic complications.  

• Haemolysis, elevated liver enzymes, low platelets (HELLP syndrome)

HELLP syndrome is a severe variant to pre-eclampsia and eclampsia. Patients can present with symptoms of acute vision loss. Fundoscopy may reveal retinal artery and vein occlusions, serous RDs (Figure 4) and Purtscher-like retinopathy with multiple white retinal patches and retinal haemorrhages. 

• Antiphospholipid Antibody Syndrome (APS)

APS is an autoimmune condition and 14-18% of patients present with ocular symptoms. Clinical signs include conjunctival microaneurysms or telangiectasia, episcleritis, keratitis and iritis. Posterior segment manifestations include RD, posterior scleritis, vitritis, retinal arterial and vein thrombosis. Patients are treated with long-term anticoagulants and visual prognosis is good. Patients should be promptly referred to their physician and ophthalmologist for further management. 

• Thrombocytopenic Purpura (TTP)

TTP, a haematological disorder, is characterised by microangiopathic haemolytic anaemia and thrombocytopenia, renal failure and neurological disturbances which can occur during pregnancy.  

About 10% of patients with TTP can develop ocular complications; these can include retinal findings of arteriolar constriction, exudates, retinal haemorrhage and serous RD and optic atrophy. Visual field test may show a homonymous hemianopia if there are cerebrovascular accidents affecting the retrochiasmal pathway.

• Grave’s disease

In a pregnant patient with pre-existing Grave’s disease, thyroid eye disease may have an accelerated progression in 1-2 % of these women, especially in the first trimester and postpartum. Ophthalmic examination includes orbitopathy includes proptosis, lid lag, periorbital edema extraocular muscle enlargement and fibrosis, optic neuropathy and dry eyes.

• Pituitary adenoma

A previously undetected pituitary adenoma may manifest itself during pregnancy because of the physiological pituitary gland enlargement during pregnancy. 

If any pregnant patient presents with headache, decreased visual acuity and diplopia, visual field changes especially of bitemporal hemianopia, she should be referred to an ophthalmologist and/or general practitioner promptly so that appropriate investigations with neuroimaging are performed.⁹ 

These patients will need a baseline ophthalmic evaluation including field evaluation and OCT retinal nerve fiber layer thickness and ganglion cell plot, that will help to guide the chronicity of any chiasmal compression. Most adenomas will regress following pregnancy leaving no vision compromise postpartum.

• Occlusive vascular disorders

Arterial occlusion in the form of central retinal artery occlusion (CRAO) and branch retinal artery occlusion (BRAO) can occur in pregnant patients with hypercoagulability state. Patients can present with sudden onset of painless vision loss or visual field disturbances. 

Ophthalmic medications during pregnancy 

Risk of ophthalmic drugs to the foetus needs to be considered while treating a pregnant mother. Any medication should be used in a pregnant woman only if the benefit to the mother outweighs risk to the foetus. 

Systemic absorption of topical medications (more commonly with drops than ointment) can occur via the conjunctival vessels or the nasal mucosa. Systemic absorption can be reduced by nasolacrimal occlusion for a few minutes after instillation of drops. 

In addition, drugs should be used at the minimal effective dose and for the minimal duration. If possible, they should be avoided in the first trimester.^10,11

Conclusion

Physiological ophthalmic manifestations are common in pregnancy and may account for majority of patient’s symptoms. However, it is important to recognise pathological ocular diseases that can be encountered in pregnancy either de novo or as a result of complications during pregnancy. 

Patients presenting with red flag symptoms and signs should be referred to an ophthalmologist. In addition, pre-existing eye conditions need to be cautiously monitored during pregnancy to avoid blinding eye diseases. While systemic absorption of ophthalmic medications is small, medications should be avoided unless necessary during pregnancy to prevent foetal harm. 

More reading

Co-management of cataract patients in real-world Australian setting

Paediatric dry eye care

Traumatic brain injury: diagnosis and management of vision impairment

References

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