Normal Tension Glaucoma: Who Needs Neuroimaging?

1
Normal Tension GlaucomaWho Needs Neuroimaging?

• Julie Falardeau, MD, FRCSC
• Casey Eye Institute
• Devers Eye Institute
• Portland, Oregon

2
Background

• Normal tension glaucoma (NTG) is characterized
  by
• Cupping of the optic nerve head
• Visual field loss
• Intraocular pressure (IOP) ? 21 mmHg
• No obvious or apparent cause for these changes

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Nonglaucomatous optic disc cupping

• Following an ischemic optic neuropathy (anterior
  or posterior - AION or PION)
• Temporal arteritis
• Quigley and Anderson found that 50 of patient
  with arteritic -AION developed cupping, compared
  to 10 after non-arteritic-AION
• Severe hypotensive/hypovolemic event
• Demyelinating optic neuritis

Quigley et Anderson. Cupping of the optic disc in
ischemic optic neuropathy. Trans Am Acad
Ophthalmol Otol. 197783755-762
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Nonglaucomatous optic disc cupping

• Hereditary optic neuropathy
• Lebers hereditary optic neuropathy
• Autosomal dominant optic atrophy
• Temporal disc excavation and pallor
• Traumatic optic neuropathy
• Infectious
• Syphilis
• Toxic
• Methanol

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Nonglaucomatous optic disc cupping

• Compressive lesion
• Meningioma
• Aneurysm
• Dolichoectasia of the internal carotid artery
• Suprasellar mass

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Glaucomatous VS Nonglaucomatous cupping

• Distinguishing glaucomatous from non-glaucomatous
  disc cupping is often difficult
• A detailed history is crucial
• Presence of neurological symptoms
• Chronicity and pattern of visual loss
• History of head trauma
• History of shock or severe low blood pressure

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Glaucomatous VS Nonglaucomatous cupping

• Systematic approach recommended
• Demographic characteristics
• Visual acuity
• Optic disc characteristics
• Visual field findings

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Demographic characteristics

• A family history of glaucoma among first degree
  relatives is highly specific (96) for
  glaucomatous cupping
• Age under 50 years is 93 specific for
  nonglaucomatous cupping

Greenfield et al. The cupped disc Who needs
neuroimaging? Ophthalmology. 19981051866-1874
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Visual Acuity

• Patients with nonglaucomatous cupping have
  significantly lower levels of visual acuity than
  patients with glaucoma
• Trobe et al found all 20 patients with
  compressive optic neuropathy had loss of central
  vision
• Greenfield et al found visual acuity lt 20/40 to
  be 77 specific for nonglaucomatous cupping
• Hupp et al described sparing of central acuity in
  3 of 6 eyes with compressive lesions

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Optic disc characteristics

• Glaucomatous cupping
• Vertical elongation
• Cupping more than pallor
• Greater frequency of peripapillary atrophy
• Disc hemorrhage
• Highly specific
• Nonglaucomatous cupping
• Pallor of the neuroretinal rim
• Highly specific sign but relatively insensitive
• The absence of disc pallor does not exclude
  compressive lesions

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Optic nerve appearance

• Baring of the circumlinear vessels and temporal
  saucerization
• Common in glaucoma
• Can also be seen in compressive optic neuropathy

Kupersmith and Krohn. Cupping of the optic disc
with compressive lesions of the anterior visual
pathway. Ann Ophthalmol 198416948-53
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Visual field findings

• Glaucoma
• Nerve-fiber-layer (arcuate) defects, bordering
  horizontal midline
• Arcuate scotoma
• Nasal step
• Compressive lesion
• Central scotoma
• Temporal hemianopia
• Incongruous hemianopia respecting the vertical
  meridian
• Glaucomatous types of VF defects can occur

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Humphrey perimetry in patients with suprasellar
mass
Ahmed et al. Neuroradiologic screening in
normal-pressure glaucoma study results and
literature review. J Glaucoma. 2002
Aug11(4)279-86
14
NTG and Neuroimaging

• Some physicians routinely obtain neuroimaging
  studies in patients with NTG
• Cost-to-benefit ratio of performing such studies
  is unknown

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NTG and Neuroimaging

• Ahmed et al found that routine neuroimaging of
  NTG patients was cost-effective
• 6.5 of 62 consecutive patients with NTG had
  clinically significant intracranial lesions
  associated with optic neuropathy and visual field
  loss typical of glaucoma

Ahmed et al. Neuroradiologic screening in
normal-pressure glaucoma study results and
literature review. J Glaucoma. 2002
Aug11(4)279-86
16
NTG and Neuroimaging

• Steward and Reid reported compressive lesions in
  2 of 53 patients (3.8) referred for evaluation
  of NTG
• In the series by Greenfield et al, none of the
  patients diagnosed with glaucoma had
  neuroradiological evidence of compressive lesion

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NTG and Neuroimaging

• In Bianchi-Marzoli at als series of 29 patients
  with cupping from unilateral compressive lesion,
  only one had cupping and field loss as an
  isolated manifestation of their optic neuropathy
• All others had
• Reduced acuity
• Decreased color vision
• RAPD

Bianchi-Marzoli et al. Quantitative analysis of
optic disc cupping in compressive optic
neuropathy. Ophthalmology 1995102436-440.
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NTG Who needs neuroimaging?

• Presence of headache or other neurological
  symptoms
• Symptoms of decreased vision, fluctuating vision,
  or visual field loss
• Atypical visual field for glaucoma
• Visual field defect respecting the vertical
  meridian
• Junctional scotoma
• Central or cecocentral scotoma

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NTG Who needs neuroimaging?

• Atypical rate of progression of VF loss
• Monocular or binocular
• Pallor gt cupping
• Asymmetric cupping
• Especially if progressive changes while IOP
  remains symmetric and well controlled

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NTG Who needs neuroimaging?

• Most likely NTG if
• Vertical elongation of the cupping
• Presence of notch
• Presence of splinter hemorrhage
• Family history of glaucoma