Is it a fish

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Is it a fish
or is it fishy?
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ORWhen might a cupped disc be something else?

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• ??"? ??? ???? ?????? ?????? ????? - ????

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Our Patients
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Frequency

• Up to 15-25 of patients with POAG experience NTG
• In the Baltimore Eye Study
• 50 of individuals with cupping and VF changes
  had an IOP lt 21 on a single visit
• 33 had an IOP lt 21 mm Hg on 2 measurements

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NTG and compressive lesions

• Both can cause ONH cupping
• Both can produce VF changes
• Compression of the ON may make the nerve
  susceptible to damage at normal Tension

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Do I need to image?

• Yes Occasional pathology found, Kastach
  difficult patients
• No Low cost effectiveness, unnecessary
  radiation (CT)

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Compressive lesions to consider in NTG

• Meningiomas
• Craniopharyngiomas
• Pituitary tumors
• Cysts
• Chordomas

• Compression by normal carotid artety
• Aneurysms affecting
• the prechiasmal and/or chiasmal visual pathways.

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Compression by ICA

• Gutman and Melamed (Graefes 1993) studied by CT
  62 patients with NTG
• 90 had either calcification or dilation of the
  ICA adjacent to the opening of the optic canal
• Only 21 of age matched controls had similar
  abnormalities

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N. Ogata - BJO 2005

• Retrospective, 103 eyes with NTG, 104 controls
• Compressive optic neuropathy by ICA in 49.5 of
  NTG patients
• 34.6 in age matched controls
• Bilateral compression
• 40.7 of NTG
• 21.2 in controls
• C/D gt 0.7 higher frequency of ICA compression

Neurosurgical decompression? dont rush
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Sheba Hospital (RHB)

• 40 consecutive NTG suspects referred to the
  neuro-ophthalmology clinic
• Complete neuro-ophthalmic exam
• Review of scans by neuro-ophthalmologist (RHB)and
  neuro-radiolosist (MB)

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Results
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NTG - Suspected findings

• gt visual complaint
• gt color vision defect
• gt optic disc pallor
• gt atypical visual field defect for glaucoma

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Greenfield - Oph 1998

• A retrospective case-controlled study
• Fifty-two eyes of 29 NTG patients
• All had brain CT or MRI as part of a diagnostic
  evaluation between 1985- 1995
• Comparison group
• 44 eyes of 28 patients withcompressive lesions
  and increased C/D ratio

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RESULTS

• None of the patients diagnosed with glaucoma had
  radiologic evidence of a mass lesion in the
  anterior visual pathway

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Group characteristics

• Compressive lesions
• Younger lt50 y
• VA lt 20/40
• No disc hemorrhage
• Mostly pallor
• Vertically aligned defects

• Glaucoma patients
• Older 68.7 y
• Better VA
• Vertical cupping
• Disc hemorrhage (13)
• Less NR pallor
• HVF arcuate defects aligned horizontally

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CONCLUSIONS

• Anterior visual pathway compression is an
  uncommon finding in the neuroimaging of patients
  with suspected NTG.
• Younger age, lower levels of visual acuity,
  vertically aligned visual field defects, and
  neuroretinal rim pallor may increase the
  likelihood of identifying an intracranial mass
  lesion.

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Ahmed - Methods

• A prospective, comparative, observational case
  series, 1988-1998
• 62 consecutive NTG patients had MRI
• 70 progressive POAG with controlled IOP .
• The prevalence of intracranial compressive
  lesions, demographic data, and clinical
  characteristics were compared.
• J Glaucoma, 2002

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RESULTS

• 4 of the 62 (6.5) patients withNTG had
  clinically relevant intracranialcompressive
  lesions involving the anterior visual pathway
• 2 pituitary macroadenoma, 1 meningioma, 1
  arachnoid cyst
• None of the 70 patients with POAG had a
  compressive lesion (P 0.039)

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What is the diagnosis?
24-2 HVF of a patient with pituitary macroadenoma
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What is the diagnosis?
HVF of a patient with an arachnoid cyst
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CONCLUSIONS

• Intracranial compressive lesions are an important
  diagnostic consideration in the workup of
  normal-pressure glaucoma
• Ahmed Neuroimaging is cost-effective
• Remember
• Compressive lesions can cause cupping and mimic
  glaucomatous VF defects!!!
• Trobe et al, Arch oph 1980

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Red Flags

• Mismatch between the cupping and the visual field
  loss (C/D 0.5 but 10- VF remaining).
• An APD or visual acuity loss out of proportion to
  the VF loss or cupping.
• Rapid progression of visual loss.
• Glaucomatous-appearing visual field loss in a
  patient with an anomalous or hypoplastic optic
  nerve (where cupping is hard to judge).

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Indications for neurological workup

• Unexplained reduction of visual acuity
• Color vision loss w/o advanced VF loss
• visual field loss out of proportion to cupping
• VF loss atypical for glaucoma
• Optic nerve pallor in excess of cupping
• Neurological symptoms.

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I agree with the authors

• If it looks like normal-tension glaucoma, you do
  not have to do neuroimaging
• to sleep at night.
• Richard Mills, Discussion on Greenfield

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