Ординатура / Офтальмология / Английские материалы / Moorfields Manual of Ophthalmology_Jackson_2007

Lesions are extradural so rupture is less likely to be fatal than an intradural berry aneurysm. Endovascular embolization may be required if visual loss progresses.

7.Carotid cavernous fistula : see page 675.

8.Vasculitis : see page 655.

■Vertebrobasilar territory:

1.Occipital stroke : produces a congruous homonymous hemianopia of sudden onset, often with macular sparing. Usually ischaemic rather than haemorrhagic. Bilateral cortical blindness may result from ‘top of the basilar’ artery occlusion.

2.Anton’s syndrome : patients with bilateral cortical blindness and damage to the visual association areas may deny blindness and claim to see normally. Extrastriate strokes may produce selective disorders of submodalities of vision such as colour (cerebral achromatopsia), spatial vision (Balint’s syndrome), or face recognition (prosopagnosia).

3.Vertebrobasilar dissection : features include bilateral transient visual obscurations lasting 1–5 minutes, transient vertigo, hearing abnormalities, dysarthria, diplopia, unilateral limb numbness or weakness, perioral numbness or tingling, reduced coordination and gait instability, and sudden loss of consciousness. Eye examination is usually normal. There may be abnormal eye movements, nystagmus, and other cerebellar or brainstem signs if seen during an episode. Patients with marked stenosis of the vertebrobasilar circulation may precipitate symptoms by neck movements or postural changes. Imaging confirmation may be problematic. Anticoagulation is advised.

4.Basilar thrombosis : may begin with focal brainstem signs and may progress to a fatal outcome. Urgent referral is essential.

5.Transient homonymous hemianopia : may be considered a type of TIA caused by emboli, usually lasting a few minutes but may last several hours. Consider migraine as an alternative explanation (p. 652).

6.Transient binocular visual loss : consider basilar artery emboli and postural hypotension.

■Dural sinus thrombosis:

1.Produces headache, papilloedema, and visual obscurations (p. 647).

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Cerebrovascular disease

Differential diagnosis Consider hypotension, bilateral carotid disease (symptoms may occur on exposure to bright light), giant cell arteritis, narrow angle glaucoma, occipital epilepsy, migraine (lasts longer with scintillations), and raised intracranial pressure (lasts seconds not minutes).

Investigations Request Humphrey 24–2 field test and other tests as detailed below.

Management

■Casualty : for presumed atherosclerotic disease start aspirin 75 mg o.d. if not contraindicated. Advise smokers to stop. Check FBC, ESR, CRP lipids, fasting glucose, and refer to clinic soon or to a neurologist.

■Clinic : confirm the diagnosis, check results, and refer to stroke assessment clinic for further management, e.g. MR angiography, transoesophageal echocardiogram, ECG, 24-hour ECG, and anticoagulation.

Follow–up Check visual fields and VA remain stable and exclude disc swelling. Follow for about 1 year then discharge if there are no new symptoms.

Carotid Cavernous Fistula

Background Occurs when the arterial circulation connects directly to the venous circulation in the cavernous sinus. May follow blunt head trauma (80%) or occur spontaneously, especially in hypertensive patients. May be high-flow (direct) or low-flow (indirect, dural arteriovenous malformations).

Symptoms Direct lesions produce a sudden onset of a whooshing noise in the head. Vision may be blurred with minor ocular discomfort. The indirect type is less severe, slower onset, and tinnitus may be absent.

Signs Patients are apyrexic, usually with unilateral proptosis. Eye movements are limited by a combination of nerve palsy and swelling. There is conjunctival chemosis (Fig. 14.18) with engorged vessels that become arterialized, with a spiral appearance near the limbus. Other features include exposure keratopathy, raised IOP with increased pulse pressure, poorly reactive mid-dilated pupil, and congested retinal veins. Central retinal vein occlusion and optic disc swelling may occur.

History and examination Document any history of head trauma, hypertension, previous thyroid problems, or diplopia. Lid

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retraction is not seen. Record temperature, proptosis, eye movements, VA, confrontation fields, corneal exposure, IOP, and RAPD. Listen for an orbital bruit with the bell of the stethoscope over the globe, forehead, and temple.

Differential diagnosis Consider severe scleritis, cavernous sinus thrombosis, and orbital disease including thyroid, cellulitis, abscess, neoplasia, and inflammatory lesions (idiopathic, myositis, Wegner’s).

Investigations Arrange urgent ultrasound to look for dilation and reversed flow in the superior ophthalmic vein. Request vascular sequence CT/MRI, or digital subtraction angiography (DSA) that commonly reveals an enlarged superior ophthalmic vein and cavernous sinus ± proptosis, enlarged extraocular muscles, and increased fat vascular markings. Request FBC, ESR, glucose, and TFTs.

Treatment Admit patients. Prescribe topical lubricants and treat elevated IOP with drops ± oral acetazolamide. Record daily VA, Ishihara plates, fields, and IOP. Life-threatening nose bleeds may occur, occasionally requiring emergency carotid ligation. Some fistulas also drain into the cerebral venous system and predispose to cerebral vascular accidents.

Direct carotid cavernous fistulas usually require embolization to close them, with 85% success. Indirect fistulas often close spontaneously and may be observed if the vision is not deteriorating; if progressive visual loss occurs then consider endovascular fistula embolization. Some fistulas close following angiography alone without any attempt at embolization. Thrombosis of the superior ophthalmic vein may cause a paradoxical worsening of proptosis for a few weeks before symptoms improve. Stereotactic radiosurgery has been used occasionally. Avoid glaucoma filtration surgery as suprachoroidal haemorrhage may result.

Follow–up Until resolution occurs.

Medically Unexplained

Visual Loss

Background There are four types of medically unexplained visual loss:

■Undiagnosed organic disease.

■Malingerers with a secondary gain.

■Psychosomatic visual loss, often due to serious emotional stress. Patients genuinely believe they have lost vision. Also called hysterical, functional, or nonorganic loss.

■Munchausen’s syndrome and Munchausen’s by proxy.

For children with reduced vision but an otherwise normal examination, see also page 579.

Clinical features Malingerers typically have unilateral blurred vision. Functional loss is bilateral in 70%. VA is typically 6/12 to NPL. Examination is normal, although note any evidence of self-harm or eye rubbing.

History and examination A full history is essential. Ask if there is any ongoing litigation or compensation claim or any stressful event, e.g. divorce, bereavement. Observe behaviour. Is navigation consistent with VA? Test VA at 6 and 2 metres to see if the Snellen fraction is similar. Test near VA and Ishihara plates: are these consistent with the VA.

Place a +1 dioptre lens in one side of a trial frame, and cover fellow eye. Explain that you are adding a stronger ( −1 dioptre) lens to see if a spherical equivalent of zero improves vision. Use an OKN drum to elicit nystagmus or move a mirror in front of the patient who will track their reflection unless genuinely NPL. Check for an RAPD.

Differential diagnosis Exclude the following by thorough history and examination: tear film abnormality; keratoconus; refractive error; presbyopia; intermediate uveitis; central serous retinopathy; macular dystrophy; central retinal artery occlusion; drug toxicity (e.g. quinine); amblyopia; optic nerve/chiasm disease, especially retrobulbar neuritis; traumatic optic neuropathy; and cortical blindness.

Investigations A Goldmann field may show spiralling (Fig 14.19) but tired patients may also show this. Hospital refraction is advisable. Electrodiagnostic testing is very useful to confirm the integrity of the visual pathways and MRI of brain and orbits are sometimes required. Fluorescein angiography is occasionally helpful.

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3 0

2 0

1 0

1 0

2 0

3 0

Fig. 14.19: Spiral field on a Goldmann field test.

Treatment

■Casualty : for malingerers explain that the eye findings are not typical of the proposed injury mechanism, that there is no objective evidence of irreversible visual loss, and that a followup appointment by a senior colleague is appropriate to check that everything has resolved. Those with functional loss should be reassured that there is nothing seriously wrong and that stress is a likely explanation. Tell them their vision should improve and this will be confirmed in clinic. Routine clinic appointments are adequate unless the diagnosis is uncertain.

■Clinic : confirm the diagnosis. Functional loss does not exclude eye disease.

Follow–up Review until the vision has recovered fully. Most children and adolescents recover with reassurance. Adults tend not to improve as quickly if the secondary gain or psychological illness persists. Liaise with the patient’s general practitioner about psychological assessment if appropriate.

Systemic Disease Associations

Chronic progressive external ophthalmoplegia (CPEO) A feature of many different mitochondrial myopathies. Presents with bilateral ptosis with ophthalmoplegia later. May have generalized muscle weakness. Usually symmetrical so no diplopia, except for reading. Consider prisms on reading glasses, ptosis props, or cautious lid-raising surgery. For Kearn-Sayre syndrome (CPEO with pigmentary retinopathy) see page 497.

Progressive supranuclear palsy Also known as Steele- Richardson-Olszewski syndrome. Loss of downward saccades occurs first, then up saccades, and eventually complete ophthalmoplegia. There is progressive dementia, and stiff neck and trunk leading to falls. MRI shows midbrain atrophy with dilated ventricles. The differential includes parkinsonism, diffuse Lewy body disease, and multisystem atrophy. Avoid bifocals.

Myotonic dystrophy Autosomal dominant with genetic anticipation. This means that trinucleotide repeat sequences become ever longer with each generation and this typically results in progressively more serious disease with each generation.

■Systemic features : frontal balding, sunken temples, long face, peripheral weakness and wasting of muscles with myotonia,

testicular atrophy, cardiac conduction defects, nocturnal hypoventilation, ± mild intellectual impairment.

■Ocular features : bilateral ptosis ± orbicularlis weakness, slow saccades, varying degrees of ophthalmoparesis, cataracts in almost all patients (coloured crystals), retinal pattern dystrophy.

Sturge–Weber syndrome Sporadic condition.

■Systemic features : port wine stain, ± epilepsy, hemiplegia, and intracranial calcification on skull X-ray.

■Ocular features : homonymous field defect, glaucoma, and diffuse choroidal haemangioma. Consider in cases of unilateral glaucoma as patients may have covered the naevus with make-up.

Tuberose sclerosis Autosomal dominant disease with multiple hamartomas affecting many systems.

■Systemic features : ash leaf spot, shagreen patch, adenoma sebaceum over nasolabial folds, subungal fibromas, epilepsy, periventricular astrocytic hamartomas, and mental retardation may occur.

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■Ocular features : retinal hamartomas (50%) may be flat, translucent lesions or multinodular ‘mulberry’ lesions (astrocytic hamartomas) – these are benign and rarely enlarge; optic nerve hamartoma; hypopigmented patches on iris.

Neurofibromatosis type I Dominantly inherited.

■Systemic features : 6+ café au lait spots; neurofibromas; axillary freckling; phaeochromocytomas; meningioma; multiple tumours of the brain, spinal cord, and nerves.

■Ocular features : optic nerve glioma (15%, only 1% progress and need treatment); >1 Lisch nodules (iris hamartomas present in 90% of those aged >6 year); congenital glaucoma; upper eyelid plexifrom neurofibroma (± ipsilateral glaucoma); retinal hamartomas; choroidal hamartomas; thickened corneal nerves; pulsatile proptosis (absent greater wing of sphenoid).

Neurofibromatosis type II Dominantly inherited.

■Systemic features : bilateral vestibular schwannomas; meningioma (4%); other CNS tumours; café au lait spots (60%).

■Ocular features : early-onset cortical or posterior subcapsular cataracts (81%); retinal hamartomas (combined hamartomas of retina and RPE, 22%); optic nerve sheath tumours; Lisch nodules are rare.

Von Hippel–Lindau syndrome Dominantly inherited.

■Systemic features : cerebellar, brainstem or spinal haemangioblastomas (25%); phaeochromocytomas; renal cell carcinoma. Regular imaging is required to look for tumour development.

■Ocular features : Retinal capillary angiomas characterized by a large feeder artery and dilated draining vein. Leakage may cause decreased vision, exudate deposition or serous retinal detachment. Treatment is with extensive laser photocoagulation or cryotherapy.

Wyburn–Mason syndrome Retinal racemous angioma associated with intracranial arteriovenous malformation. Request brain MRI.

Ataxia telangiectasia (Louis–Bar syndrome) Autosomal recessive. The most common

progressive ataxia of childhood. Thymic hypoplasia and defective immune system results in recurrent infections. Conjunctival telangiectasia is common.

Optometry and General

Practice Guidelines

General comments

Many neuro-ophthalmic symptoms are non-specific and it is not always clear if they should be managed by a general practitioner, neurologist, ophthalmologist, or other specialist. Thus, transient loss of vision might reflect systemic disturbance such as hypoglycaemia or hypotension, carotid emboli, or raised intraocular pressure (IOP).

Headache can be caused by several eye conditions and the following questions may help:

■Is the headache precipitated by visual attention? This may suggest refractive error or ocular muscle imbalance.

■Is headache associated with a red eye? This may suggest uveitis, scleritis, or acute angle closure glaucoma. Mild or moderately raised IOP does not usually cause headache or a red eye.

■Is headache associated with blurred vision? Consider high IOP, uveitis, raised intracranial pressure, optic neuritis, and migraine. A careful history can usually distinguish migrainous photopsia from those associated with retinal detachment (p. 556).

General practice

Although rare in general practice, always consider giant cell arteritis in those aged over 50 years with jaw claudication and temporal tenderness, especially those with polymyalgia rheumatica; an ESR and or CRP is helpful in this setting. Assessment of refraction, anterior chamber depth, IOP, dilated fundoscopy, optic discs, ocular muscle balance, and screening field tests can usually be undertaken via an optometrist and will help exclude many eye conditions associated with headache. Note that patients with good visual acuity but hemianopia are usually suitable for partial-sight registration by an ophthalmologist and this may confer some benefits.

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Optometrists

An asymptomatic visual field defect picked up on routine screening should usually be repeated. Many defects will disappear as the patient learns how to perform the test. If a superior field defect is present, exclude ptosis. Tape the drooping lid up whilst the test is repeated. Exclude obvious optic disc and retinal disease with dilated fundal examination. Homonymous visual field defects (p. 639) suggest postchiasmal lesions and require relatively urgent medical assessment. For glaucomatous field defects, see page 329.

The following guide to referral urgency is not prescriptive, as clinical situations vary.

Immediate

Urgent (within 1 week)

■Sudden onset of symptomatic (oscillopsia) nystagmus. Consider ENT referral if deafness, vertigo or tinnitus are prominent features. Also consider

Soon (within 1 month)