ACUTE MONOCULAR BLINDNESS

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ACUTE MONOCULAR BLINDNESSBASIC NEURO
OPHTHALMOLOGY

• Almero Oosthuizen
• UCT/US Emergency Medicine
• January 2009

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PERSPECTIVEWhy is this important?

• SMALL problems with the eye causes BIG problems
  for the patient
• EYE problems may be markers for serious SYSTEM
  problems

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OUTLINE

• Basic Neuro Ophthalmology
• Visual, reflex and gaze pathways
• Some clinical findings
• Overview of sudden visual loss
• Acute monocular blindness
• Overview and some conditions
• Summary

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BASIC VISUAL PATHWAYS
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PUPILLARY REFLEXES

• Reaction to light (direct and consensual)
• Reaction to accommodation
• Autonomic reflexes

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PUPIL MUSCLE ACTIONS
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LIGHT REFLEX PATHWAYS
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LIGHT REFLEX PATHWAYS
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LIGHT REFLEX PATHWAYS
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AFFERENT PUPILLARY DEFECT

• Total loss of the AFFERENT reflex pathway
• Blind eye, i.e. severe retinal damage or optic
  nerve pathology
• For a LEFT APD
• Light into left eye no direct light reflex (L)
• Light into left eye no consensual reflex (R)
• Light into right eye normal direct and
  consensual reflex

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RELATIVE AFFERENT PUPILLARY DEFECT

• Incomplete damage to AFFERENT pathway
• Partial retina or optic nerve damage
• For LEFT RAPD
• Light into left eye left and right pupil
  constrict
• Light into right eye both pupils constrict
  further
• Back to left eye both pupils dilate, but not
  completely
• Light away both pupils dilate completely

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SOME OTHER PUPIL DEFECTS
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ACCOMODATION VS. LIGHT

• Accommodation pathway visual cortex to CNIII
  nucleus
• Absent light, Intact accommodation
• Midbrain lesion (i.e., Argyll Robertson,
  syphilis)
• Cilliary ganglion lesion (i.e. Adies pupil)
• Failure of accommodation alone
• Midbrain lesion (occasional)
• Cortical blindness

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CONJUGATE GAZE PATHWAYS
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INTERNUCLEAR OPHTHALMOPLEGIA

• Caused by a brainstem lesion involving the MLF
• Common in Multiple Sclerosis
• Sometimes with small brainstem infarcts

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INTERNUCLEAR OPHTHALMOPLEGIA

• Right INO
• Lesion of right MLF
• On attempted left lateral gaze
• Right eye fails to ADduct
• Left eye develops coarse nystagmus in ABduction
• The side of the lesion the side of the failed
  ADduction, NOT the side of the (more obvious)
  nystagmus

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INTERNUCLEAR OPHTHALMOPLEGIA
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BLINDNESS OUTLINE

• Basics of blindness
• Clinical approach
• Monocular blindness

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BLINDNESS BASICS

• Decrease in visual function with varying degrees
  of
• Loss of visual acuity
• Visual field defects
• Abnormalities of visual information processing
• Multiple etiologies, basically divided
• Eye problems
• Neuro-ophthalmological problems
• Functional visual loss

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ETIOLOGY

• Three groups
• Eye, neuro-ophthalmological, functional
• Primary diseases of the eye
• I.e. glaucoma
• Systemic diseases INVOLVING the eye
• I.e. hypertension, diabetes, infections
• Systemic diseases AFFECTING the eye
• I.e. thromboembolic events (RAO)

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REMEMBER THE ANATOMY!
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TIMEFRAME AND PAIN

• Transient (lt24hr)
• Persistent (gt24 hr)
• Sudden, painless
• Gradual, painless
• Painful
• Monocular anterior to chiasm
• Binocular posterior to chiasm

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TRANSIENT (lt24 HR)

• Seconds
• Papilledema
• Minutes
• TIA (amarausus fujax) - unilateral
• Vertebrobasilar artery insufficiency bilateral
• Minutes to an hour
• Migraine
• Sudden BP changes

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PERSISTENT (gt24 hr)

• Sudden, Painless
• Retinal artery or vein occlusion
• Vitreous bleed
• Retinal detachment
• Optic neuritis/neuropathy
• Temporal arteritis

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PERSISTANT (gt24 hr)

• Gradual and painless
• Cataract
• Age
• Refraction
• Open-angle glaucoma
• Chronic retinal disease
• Macular degeneration
• Diabetic retinopathy
• CMV retinopathy
• SOL

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PERSISTANT (gt24 hr)

• Painful
• Corneal abrasion or ulcer
• Angle closure glaucoma
• Optic neuritis
• Iritis/uveitis
• Keratoconus with hydrops
• So, mainly EYE problems

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NEURO-OPHTHALMOLOGICAL

• Visual loss not readily explained my an
  abnormality on physical examination
• Pre-Chiasmal (often monocular)
• Optic neuritis
• Ischemic optic neuritis
• Compressive optic neuritis
• Toxic and metabolic optic neuritis

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NEURO-OPHTHALMOLOGICAL

• Chiasmal
• Chiasmal compression from pituitary or other IC
  tumours
• Classically bitemporal hemianopia
• SOLs may compress asymmetrically!
• Post-Chiasmal
• CVA
• Tumour
• AV malformation
• Migraine

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CLINICAL APPROACH

• Rapid assessment to find and treat reversible
  conditions
• Remember to consider systemic implications
• As always
• History
• Physical
• VA, pupils, fundoscopy, inspection of the globe
  (fluoresscine!)
• Use an anatomical system
• Tests

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ACUTE MONOCULAR BLINDNESS

• Always an emergency
• Neuro-ophthalmological (see before)
• Problems BEHIND the eye
• Pre-chiasmal group (mainly optic
  neuritis/neuropathy)
• Non neuro-ophthalmological
• Problems WITH the eye

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NON NEURO-OPHTHALMOLOGICAL

• Central retinal artery occlusion
• Central retinal vein occlusion
• Temporal arteritis
• Retinal breaks and detachment
• Vitreous bleed
• Retinal/macular disease
• incl retinal vasculitis, CMV etc
• Corneal disease (trauma, ulcers etc)
• Glaucoma
• Iritis/uveitis (incl ant chamber bleed)
• Lens detachment
• Many other, more obscure causes

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CENTRAL RETINAL ARTERY OCCLUSIONGeneral

• Abrupt, painless, usually unilateral blindness
• Usually some degree of permanent loss if not
  corrected immediately
• ICA -gt ophthalmic artery -gt retinal artery
• Occasional additional supply by the cilioretinal
  art.

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CENTRAL RETINAL ARTERY OCCLUSIONEtiology

• Same as for any thromboembolic disease
• ICA atherosclerosis (all the usual CVA risk fs)
• Cardiac emboli (AF, SIBE etc)
• Other (often systemic) problems
• Haematological disease (i.e. sickle)
• Hypercoagulable states
• Autoimmune/inflammatory states (i.e. lupus, GCA)

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CENTRAL RETINAL ARTERY OCCLUSIONClinical

• Blindness sudden, dramatic, painless
• Often only a small unaffected area
• May be transient or stuttering
• TAPD or RAPD
• Fundus
• Pale, edematous retina, may see embolis
• Macula cherry red spot (underlying choroid)
• May see cholesterol plaques etc

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CENTRAL RETINAL ARTERY OCCLUSIONFundus
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CENTRAL RETINAL ARTERY OCCLUSIONTreatment

• Not much helps. Almost everyone does badly
• Act fast!
• gt240min irreversible damage lt100 min best
  chance of benefit
• Ocular massage
• Press for 15s on closed lid, release suddenly,
  repeat for 15 min
• Decrease IO pressure
• Ant chamber paracentesis (ophthalmologist), IV
  diuretics, trabeculectomy
• Other strategies (insufficient evidence,
  ophthalmologist decides)
• Lytics (riskbenefit), vasodilators etc.
• OPHTHALMOLOGIST EARLY

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CENTRAL RETINAL VEIN OCCLUSIONGeneral

• BRVO vs. CRVO
• Ischemic vs. Non-Ischemic
• Caused by
• Crossing of art/ven, with ven compression and
  stasis/thrombosis
• Thrombosis in the main draining retinal vain
• Results in
• Disk/retinal edema, hemorrhage, vascular leakage
• Complications
• Neovascularisation and glaucoma

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CENTRAL RETINAL VEIN OCCLUSIONClinical

• BRVO
• Milder symptoms, often noticed on routine exams
• CRVO
• Sudden, unilateral visual loss. Painless. Often
  dramatic, often more central
• Classically noticed upon waking in the morning
• Variable TAPD/RAPD
• Fundus
• Disc edema, bleeds, cotton-wool spots, tortuous
  veins
• Blood and thunder!

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CENTRAL RETINAL VEIN OCCLUSIONFundus
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CENTRAL RETINAL VEIN OCCLUSIONTreatment

• Not much works, and basically nothing in the
  acute setting
• Find systemic problems
• Refer to an ophthalmologist
• They may try many therapies
• As for CRAO, plus hemodilution, laser
  photocoagulation, steroids

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OPTIC NEURITISGeneral

• Focal inflammatory demyelination of the optic
  nerve (bulbar vs. retro bulbar)
• Causes acute, painful monocular blindness
• Most common in 20y 40y age group, female
  preponderance
• Approx. 30 will go on to develop MS
• 31 will have recurrence of optic neuritis within
  10 years
• Consultation with ophthalmology and neurology is
  advisable

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OPTIC NEURITISClinical

• Acute visual disturbance
• Hours to days
• Often initial loss of colour discrimination and
  contrast
• Loss mostly central
• Monocular and painful
• Typically pain on moving the eye
• Always some degree of APD
• Natural History
• Worst in about one week, then gradually better
  over several weeks

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OPTIC NEURITISFundus

• May be normal in up to 66 (retro bulbar)
• Rest may have
• Optic disk swelling
• Blurring of disk margins
• Swollen retinal veins

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OPTIC NEURITISMore pictures
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OPTIC NEURITISTreatment

• Controversial
• Steroids
• Hastens visual recovery, and may delay onset of
  MS, but no benefit beyond 2y compared to placebo
• So talk to ophthalmology, and discuss with
  neurology re work-up for MS
• May offer gadolinium enhanced MRI
• Talk to patients regarding risk for MS

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OTHER OPTIC NERVE PROBLEMS

• Please see enclosed information pack
• Examples include
• Ischemic optic neuropathy (i.e. with Temp Art)
• Nonarteritic ischemic optic neuropathy
• Compressive optic neuropathy
• Toxic and metabolic optic neuropathy
• Methanol, chloramphenicol, INH, antifreeze,
  ethambutol, thiamine deficiency, pernicious
  anaemia

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TEMPORAL ARTERITISGeneral

• Medium- and large-vessel vasculitis
• Extra cranial branches of the carotid artery
• Very rare below 50y, peak 70 80y
• 21 female to male
• Etiology
• Poorly understood, possibly an infective trigger
• Pathophysiology
• CD4 cell mediated granulomatous inflammation with
  giant cells
• Reactive intimal proliferation with occlusion of
  the lumen (not thrombosis)
• This causes an ischemic optic neuropathy

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TEMPORAL ARTERITISClinical

• Most common features
• Headache
• Constitutional symptoms (cytokines)
• Tender, hardened temporal/occipital arteries
• Other features
• Tongue/jaw claudication, neuropathies etc
• Visual features
• Visual loss or disturbance, often preceded by
  amarousis fujax, may experience diplopia etc.
• Usually painless and monocular, but may be
  bilateral

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TEMPORAL ARTERITISDiagnosis

• Clinical picture raised inflammatory markers
• KEY Temporal artery biopsy
• Giant cell granulomatous inflammation
• Visual findings
• Visual loss, APD
• Disk pallor and edema, scattered cotton wool
  patches, retinal bleeds

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TEMPORAL ARTERITIS
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TEMPORAL ARTERITISManagement 1

• Steroids (dont wait for biopsy)
• If any visual disturbance
• Ophthalmological emergency try to save the
  other eye!
• Many regimes, but initial high dose IV steroids,
  followed by a year or more of tapering steroids,
  protects vision
• Monitor treatment with CRP and symptoms. If
  either worsens, dont taper further

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TEMPORAL ARTERITISManagement 1

• Example regime
• 3 days IV Methylprednisolone
• 2 years of oral prednisolone (start at 40 -60mg)
• Temporal arteritis with visual loss should be
  referred to ophthalmologists
• Also remember to look for joint involvement that
  may indicate polymyalgia rheumatica

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SUMMARY

• SMALL problems with the eye causes BIG problems
  for the patient
• EYE problems may be markers for serious SYSTEM
  problems
• Acute monocular visual loss is an emergency and
  should be assessed rapidly
• Involve ophthalmology early

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Bibliography

• 5 Minute emergency medicine consult, Rosen and
  Barkin
• Textbook of emergency medicine, Rosen and Barkin
• Acute monocular visual loss, M. Vortmann et al,
  Emerg Med Clin N Am 26(2008) 73-96
• Clinical Examination, 3rd edition Talley
  OConnor Blackwell Science
• MaCleods Clinical examination Munro ed
  Churchill Livingstone
• Principles of Anatomy and Physiology, 11th
  edition G.Tortora, B.derrickson Wiley press
• Atlas of Human anatomy Frank H. Netter Ciba
  publishing