Visual disturbance in pregnancy

Visual disturbance in pregnancy is any new or worsening change in vision between conception and 6 weeks after birth, including blurring, loss of acuity, visual field defects, flashing lights, floaters, scotomata, double vision, or loss of vision.

The main clinical point is that new visual symptoms in the second half of pregnancy or in the postpartum period indicate pre eclampsia and impending eclampsia until proved otherwise, and need immediate blood pressure measurement, urinalysis and neurological examination.

Other causes include benign physiological change, migraine, diabetic and hypertensive retinopathy, retinal detachment, pituitary disease, raised intracranial pressure, optic neuritis and stroke.

Clinical relevance. Visual symptoms are present in a considerable proportion of women with severe pre eclampsia and may precede eclampsia. Delay in recognising retinal vascular occlusion, optic nerve disease or pituitary apoplexy can cause permanent loss of sight.

Anatomy and physiology. The visual system runs from the retina and optic nerve through the chiasm, tract and radiation to the occipital cortex. The site of a field defect localises the lesion: monocular loss (eye or optic nerve), bitemporal hemianopia (chiasm), homonymous hemianopia (tract, radiation or cortex). Pregnancy increases corneal thickness and curvature, reduces corneal sensitivity, alters tear film, and slightly changes refractive error; the pituitary enlarges up to 70% in size.

Mechanisms. Hypertensive and endothelial injury with vasospasm and retinal oedema (pre eclampsia); cerebral oedema in the occipital lobes (posterior reversible encephalopathy syndrome); raised intracranial pressure causing papilloedema; compression of the chiasm; thrombosis; serous retinal detachment; and immune mediated optic neuritis.

Classification by pattern. Transient visual obscuration (seconds, with postural change or raised pressure); photopsia and scotomata (migraine, pre eclampsia, retinal traction); blurring (refractive change, macular oedema, pre eclampsia); field loss (pituitary, stroke, retinal detachment); diplopia (cranial nerve palsy, myasthenia, Wernicke encephalopathy, thyroid eye disease); and sudden painless loss (vascular occlusion, retinal detachment, vitreous haemorrhage, cortical blindness).

Key distinctions. Monocular symptoms point to the eye or optic nerve, and binocular symptoms to the chiasm or brain. Associated headache, hypertension or epigastric pain points to pre eclampsia.

Pain on eye movement suggests optic neuritis. A sudden curtain suggests retinal detachment. Visual symptoms with a thunderclap headache suggest haemorrhage.

History

• Onset, duration, one or both eyes, pattern (constant, transient, episodic), type of symptom (blur, flashes, floaters, field loss, double vision, distortion, haloes, colour change), and effect on function.
• Associated: headache, nausea, vomiting, epigastric pain, swelling, eye pain, red eye, pain on eye movement, jaw claudication, scalp tenderness, weakness, numbness, speech disturbance, seizures, hearing change, tinnitus.
• Pre eclampsia: blood pressure history, proteinuria, family history, previous pre eclampsia, multiple pregnancy, obesity, chronic kidney disease, diabetes, antiphospholipid syndrome.
• Ophthalmic: refractive error, spectacle or contact lens use, previous retinal disease, glaucoma, uveitis, high myopia, laser, eye surgery.
• Diabetes: duration, control, retinopathy status, last retinal screening.
• Neurological: multiple sclerosis, migraine, idiopathic intracranial hypertension, pituitary disease, myasthenia, neuromyelitis optica.
• Obstetric: gestation, hyperemesis (Wernicke encephalopathy), postpartum haemorrhage and failed lactation (Sheehan syndrome), preterm labour.
• Drugs: topiramate, antihistamines, hydroxychloroquine, ethambutol, vitamin A, corticosteroids, oral contraceptive history, bromocriptine, cabergoline.
• Infection: toxoplasmosis, cytomegalovirus, syphilis, tuberculosis, HIV, recent cat contact.
• Family history: glaucoma, retinal detachment, hereditary eye disease.
• Region specific: nutritional vitamin A deficiency, onchocerciasis, trachoma, malaria.

Examination

• Blood pressure (repeat), pulse, temperature, glucose, urine dipstick for protein.
• Visual acuity with correction and pinhole, near vision, colour vision (Ishihara plates), contrast sensitivity.
• Pupils: size, reaction, relative afferent pupillary defect.
• Visual fields to confrontation (each eye), followed by formal perimetry.
• Eye movements, alignment, diplopia, ptosis, nystagmus.
• External eye: lids, conjunctiva (redness, discharge), cornea (clarity), anterior chamber, intraocular pressure by tonometry.
• Fundoscopy through dilated pupils when safe: optic disc (swelling, pallor), vessels (spasm, occlusion, venous pulsation), retina (haemorrhages, cotton wool spots, exudates, detachment), macula.
• Neurological examination: cranial nerves, limb tone, power, reflexes (hyperreflexia, clonus), gait, meningism.
• Systemic: breasts and lactation (Sheehan), thyroid, temporal arteries, heart and carotids.

Red flags

• Visual disturbance with blood pressure 140/90 mmHg or more after 20 weeks or in the postpartum period, headache, epigastric pain, clonus, or proteinuria.
• Sudden painless loss of vision in one eye (retinal artery occlusion, detachment, vitreous haemorrhage, optic neuropathy), or both eyes (cortical blindness, posterior reversible encephalopathy syndrome).
• Bitemporal hemianopia, severe headache and ophthalmoplegia (pituitary apoplexy).
• Papilloedema with headache, vomiting (raised intracranial pressure, idiopathic intracranial hypertension, venous sinus thrombosis, mass).
• Flashing lights, new floaters and a curtain across vision (retinal detachment).
• Painful red eye with halos and nausea (acute angle closure glaucoma).
• Pain on eye movement with reduced colour vision (optic neuritis).
• Diplopia with confusion, ataxia or vomiting (Wernicke encephalopathy).
• Focal weakness, speech disturbance, facial droop (stroke).
• Jaw claudication, scalp tenderness (giant cell arteritis).
• Visual loss after postpartum haemorrhage with failure of lactation.

Special groups. Women with diabetes need retinal assessment at booking and in each trimester because retinopathy can progress rapidly. Women with high myopia need dilated retinal assessment before labour. Women with multiple sclerosis or neuromyelitis optica have more relapses in the first 3 months after birth.

Organised by site. Each cause is common unless marked serious or uncommon. Refractive and surface causes

• Refractive change from corneal thickness and curvature (usually resolves after birth; avoid changing spectacle prescription until at least 6 to 8 weeks after birth or weaning).
• Contact lens intolerance, dry eye, blepharitis, allergic conjunctivitis.
• Infective conjunctivitis, keratitis, corneal abrasion.
• Serious: acute angle closure glaucoma (rare, risk lower in pregnancy), uveitis.

Retinal causes

• Serious: hypertensive retinopathy and retinal changes in pre eclampsia (arteriolar spasm, haemorrhage, cotton wool spots, serous retinal detachment).
• Serious: diabetic retinopathy progression and macular oedema.
• Serious: retinal detachment, retinal tears, vitreous haemorrhage, posterior vitreous detachment.
• Serious: retinal artery occlusion and retinal vein occlusion (hypercoagulability, antiphospholipid syndrome, embolus from the heart).
• Central serous chorioretinopathy.
• Retinopathy of sickle cell disease, retinitis pigmentosa.
• Infections: toxoplasma retinochoroiditis, cytomegalovirus retinitis, syphilitic chorioretinitis, tuberculosis.

Optic nerve and visual tract causes

• Optic neuritis (multiple sclerosis, neuromyelitis optica, post infectious).
• Serious: idiopathic intracranial hypertension and papilloedema from any cause of raised intracranial pressure.
• Serious: compressive optic neuropathy (meningioma enlarging in pregnancy, pituitary adenoma).
• Ischaemic optic neuropathy (including giant cell arteritis).
• Toxic and nutritional optic neuropathy (vitamin B12 deficiency, ethambutol, methanol).

Chiasmal and intracranial causes

• Serious: pituitary adenoma enlargement (prolactinoma), pituitary apoplexy, Sheehan syndrome, lymphocytic hypophysitis.
• Serious: pre eclampsia, eclampsia, HELLP syndrome and cortical blindness.
• Serious: posterior reversible encephalopathy syndrome and reversible cerebral vasoconstriction syndrome.
• Serious: cerebral venous thrombosis, stroke (occipital infarction), intracerebral haemorrhage, subarachnoid haemorrhage.
• Migraine with aura and visual snow; occipital lobe seizures.
• Intracranial tumour, arteriovenous malformation, abscess.
• Cranial nerve palsies (third, fourth, sixth): diabetes, raised intracranial pressure, Wernicke encephalopathy, myasthenia gravis, thyroid eye disease, multiple sclerosis.

Systemic and metabolic causes

• Hypoglycaemia, hyperglycaemia and ketoacidosis, anaemia, hypotension and vasovagal change, dehydration, hyponatraemia.
• Vitamin A deficiency (night blindness, in malnourished women).
• Drugs: topiramate, antihistamines, antimuscarinics, hydroxychloroquine, corticosteroids (cataract and raised pressure), phosphodiesterase inhibitors, ethambutol.
• Thyroid eye disease with Graves disease.
• Giant cell arteritis, Takayasu arteritis, systemic lupus erythematosus, antiphospholipid syndrome.
• Visual hallucinations, psychosis and functional visual loss.

Stepwise reasoning

1. Exclude pre eclampsia and eclampsia first: blood pressure, urine protein, blood tests, reflexes, foetal condition.
2. Localise the problem with acuity, pupils, fields, fundoscopy and eye movements.
3. Decide whether the lesion is ocular (monocular, pain, redness), neuro ophthalmic (papilloedema, field defect, afferent defect), or intracranial (binocular, neurological signs).
4. Image the brain and venous system when there is papilloedema, field loss that localises, ophthalmoplegia, persistent headache, seizures or focal signs.
5. Arrange same day ophthalmology review for sudden loss, flashes with curtain, painful red eye, papilloedema, or any unexplained field loss.

First line tests

• Blood pressure repeated, urine dipstick and protein to creatinine ratio (over 30 mg/mmol), capillary glucose.
• Full blood count (platelets), urea, creatinine, electrolytes, liver function tests, lactate dehydrogenase, uric acid, coagulation screen.
• Cardiotocography and ultrasound for foetal wellbeing in the second half of pregnancy.
• Dilated fundoscopy by an ophthalmologist, with optical coherence tomography (safe in pregnancy), colour fundus photography and automated perimetry.
• Fluorescein angiography is avoided in the first trimester and thereafter used only if essential; indocyanine green angiography is avoided where possible.

Neuroimaging and further tests

• MRI brain with MR venography (without gadolinium): posterior reversible encephalopathy syndrome (vasogenic oedema in the parieto occipital regions), venous thrombosis, stroke, pituitary lesions (dedicated pituitary sequences), optic neuritis (orbital sequences), tumour.
• CT head and CT angiography if haemorrhage or acute stroke is suspected and MRI is not available.
• Lumbar puncture with opening pressure after imaging (idiopathic intracranial hypertension: over 25 cm of water with normal composition).
• Pituitary function: cortisol (morning, or random during stress), thyroid stimulating hormone, free thyroxine, prolactin (normally raised in pregnancy, so interpret with caution), sodium.
• Thrombophilia and antiphospholipid antibodies, inflammatory markers (erythrocyte sedimentation rate and C reactive protein for giant cell arteritis), aquaporin 4 antibody, serology for toxoplasma, cytomegalovirus, syphilis, HIV.
• Echocardiography and carotid imaging for retinal artery occlusion; electrocardiogram.
• Visual evoked potentials for optic neuritis when imaging is equivocal.

Limitations. Visual symptoms in pre eclampsia may occur at modest blood pressure levels, and the retina can look normal. Fundoscopy is difficult without pupil dilation; dilating drops (tropicamide 1%) are acceptable in pregnancy unless angle closure is suspected. MRI may be negative early in optic neuritis. Prolactin is normally raised in pregnancy and cannot diagnose a prolactinoma.

Immediate steps. Measure blood pressure and treat severe hypertension. Give magnesium sulphate to prevent seizures if pre eclampsia with neurological features is present. Position the woman in left lateral tilt after 20 weeks, give oxygen if saturation is under 94%, and arrange same day obstetric, ophthalmic and neurological review as indicated. Do not dilate the pupils in suspected acute angle closure glaucoma.

Pre eclampsia and eclampsia with visual symptoms

• Control severe hypertension (160/110 mmHg or more) within 30 to 60 minutes to systolic 140 to 150 mmHg and diastolic 90 to 100 mmHg.
• Labetalol 200 mg orally, repeated once after 30 minutes if needed. Or intravenous labetalol 20 mg over 2 minutes then 40 mg, 80 mg and 80 mg at 10 minute intervals (maximum total 220 mg).
• Or nifedipine immediate release 10 mg orally, repeated after 30 minutes (maximum 30 mg in the first hour; not sublingual).
• Or hydralazine 5 mg intravenously over 5 to 10 minutes, repeated at 20 minutes (maximum 20 mg).
• Magnesium sulphate 4 g intravenously over 5 to 15 minutes, then 1 g/h for 24 hours after birth or the last seizure. Give 2 g over 5 minutes for a repeat seizure.
• Check respiratory rate (over 12 breaths/min), patellar reflexes, oxygen saturation, urine output (over 0.5 mL/kg/h) and, in renal impairment, serum magnesium (usual range 2 to 4 mmol/L), reducing the maintenance dose to 0.5 g/h.
• Antidote: calcium gluconate 10% 10 mL (1 g) intravenously over 10 minutes.
• Delivery is the definitive treatment, with timing by gestation and condition. Betamethasone 12 mg intramuscularly twice, 24 hours apart, before 34 weeks if delivery can be delayed by 24 to 48 hours.
• Visual symptoms from pre eclampsia and posterior reversible encephalopathy syndrome usually resolve within hours to days of controlling blood pressure and delivery; serous retinal detachment reattaches spontaneously over weeks.
• Postpartum: continue blood pressure treatment and monitoring; stop vasoactive drugs.

Posterior reversible encephalopathy syndrome and reversible cerebral vasoconstriction syndrome. Control blood pressure, give magnesium sulphate for eclampsia, stop vasoactive drugs, treat seizures with levetiracetam 500 mg twice daily (maximum 3 g daily), and arrange intensive care for reduced consciousness. Nimodipine 30 to 60 mg every 4 hours is used for vasoconstriction (evidence limited).

Cerebral venous thrombosis. Therapeutic enoxaparin 1 mg/kg subcutaneously every 12 hours (reduced to 1 mg/kg once daily if creatinine clearance is under 30 mL/min), continued through pregnancy and for at least 6 weeks after birth; ophthalmology review for papilloedema.

Idiopathic intracranial hypertension. Weight control, therapeutic lumbar puncture, acetazolamide 250 mg orally twice daily after the first trimester (maximum 4 g daily), monitoring of acuity and visual fields each month, and optic nerve sheath fenestration or shunt for progressive loss.

Pituitary adenoma, apoplexy and Sheehan syndrome

• Enlarging prolactinoma with visual field loss: bromocriptine 1.25 mg orally at night with food, increasing by 1.25 mg every 3 to 7 days to 2.5 mg two to three times daily (usual 5 to 7.5 mg daily); cabergoline is an alternative. Surgery for failure of treatment or threatened vision.
• Apoplexy: hydrocortisone 100 mg intravenously, then 50 mg every 6 hours, with urgent neurosurgical decompression for visual deficit or reduced consciousness.
• Sheehan syndrome or hypopituitarism: replacement of hydrocortisone, levothyroxine (after glucocorticoid replacement) and sex hormones by an endocrinologist.

Retinal detachment, retinal tears and vitreous haemorrhage. Urgent vitreoretinal surgery or laser; pregnancy does not delay it. Caesarean section is not required for retinal disease alone, but second stage pushing may be shortened in some women with high myopia on specialist advice.

Retinal artery or vein occlusion. Same day ophthalmic and stroke assessment; aspirin 75 to 150 mg daily (low dose acceptable in pregnancy); investigate for embolic source, antiphospholipid syndrome and thrombophilia; therapeutic enoxaparin for thrombotic causes.

Diabetic retinopathy. Retinal screening at booking, at 16 to 20 weeks and at 28 weeks (sooner and more often if retinopathy is present). Laser photocoagulation if proliferative or sight threatening. Anti vascular endothelial growth factor drugs are avoided in pregnancy because evidence is limited. Control glucose gradually (target HbA1c under 48 mmol/mol, 6.5%, if safe) and avoid rapid reduction. Control blood pressure. Do not delay laser. Review again within 3 months after birth.

Optic neuritis. Methylprednisolone 1 g intravenously once daily for 3 days (corticosteroids are used with caution in the first trimester), followed by oral prednisolone as directed; plasma exchange for severe or refractory cases; evidence of benefit for the long term outcome is limited.

Giant cell arteritis. Prednisolone 40 to 60 mg orally daily, or methylprednisolone 500 to 1000 mg intravenously daily for 3 days if there is visual loss, with temporal artery biopsy or imaging and rheumatology review.

Wernicke encephalopathy. Thiamine 200 to 500 mg intravenously three times daily for 2 to 3 days, then 250 mg intravenously or intramuscularly once daily for 3 to 5 days or until improvement, then oral thiamine 100 mg daily; give before glucose; correct magnesium.

Acute angle closure glaucoma. Same day ophthalmology review; acetazolamide 500 mg intravenously then oral (avoid in the first trimester unless sight is threatened), topical timolol 0.5% and pilocarpine 2%, and laser iridotomy.

Toxoplasma retinochoroiditis. Specialist care.

Spiramycin 1 g (3 million units) orally every 8 hours before 14 to 16 weeks; after this, pyrimethamine 50 mg orally once daily with sulphadiazine 1.5 g orally twice daily and folinic acid 10 to 25 mg orally once daily. Monitor full blood count weekly.

Migraine with aura. Paracetamol 1 g orally every 4 to 6 hours (maximum 4 g daily), metoclopramide 10 mg orally (maximum 30 mg daily), and sumatriptan if needed.

Exclude secondary causes in first aura or atypical aura (lasting over 60 minutes, motor features, bilateral).

Refractive change and dry eye. Reassure, advise against changing spectacle prescription until after birth and weaning, use preservative free lubricant drops, and change contact lens regimen.

Vitamin A deficiency. Vitamin A is dosed with caution because high doses are teratogenic: 5000 IU to 10 000 IU orally daily, maximum 10 000 IU daily (3000 microgram retinol equivalents), in deficiency only, with dietary advice.

Special groups. Pregnancy: avoid gadolinium, fluorescein in the first trimester, and teratogenic drugs. Breastfeeding: methylprednisolone and prednisolone are compatible (delay breastfeeding 4 hours after a high dose). Women with multiple sclerosis: plan for relapse after birth.

Monitoring. Visual acuity and fields at each visit, blood pressure every 15 minutes during acute treatment, then four times daily, magnesium toxicity checks, repeat fundoscopy within 24 to 48 hours in pre eclampsia and in retinal disease, and optical coherence tomography as directed.

Referral and escalation. Refer the same day to the obstetric team for any visual symptom with hypertension. Refer the same day to ophthalmology for sudden loss, flashes with a curtain, a painful red eye, papilloedema or field loss. Refer to neurology and neurosurgery for papilloedema with headache, field defects, ophthalmoplegia or suspected venous thrombosis. Refer to endocrinology for pituitary disease. Refer to critical care for eclampsia and posterior reversible encephalopathy syndrome.

Admission criteria. Visual symptoms with hypertension or pre eclampsia, sudden visual loss, papilloedema, neurological signs, suspected pituitary apoplexy, venous thrombosis or stroke, uncontrolled diabetes with retinopathy progression, and acute angle closure glaucoma.

Discharge and follow up. Discharge when the cause is benign or treated, blood pressure and urine are normal, and the woman can return quickly. Arrange ophthalmology follow up within 1 week, obstetric review within 48 hours, and written information on warning symptoms. Review again 6 weeks after birth.

Safety netting. Return the same day for any new visual loss, flashing lights, floaters, a curtain across vision, double vision, severe headache, vomiting, epigastric pain, swelling, fits, confusion, weakness, or an eye that is painful and red.