Normal Tension Glaucoma:Who Needs Neuroimaging?

Julie Falardeau, MD, FRCSC

Casey Eye Institute

Devers Eye Institute

Portland, Oregon

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

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. 1977;83:755-762

Nonglaucomatous optic disc cupping

Hereditary optic neuropathy Leber’s hereditary optic neuropathy Autosomal dominant optic atrophy

Temporal disc excavation and pallor

Traumatic optic neuropathy Infectious

Syphilis Toxic

Methanol

Nonglaucomatous optic disc cupping

Compressive lesion Meningioma Aneurysm Dolichoectasia of the internal carotid

artery Suprasellar mass

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

Glaucomatous VS Nonglaucomatous cupping

Systematic approach recommended

Demographic characteristics Visual acuity Optic disc characteristics Visual field findings

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. 1998;105:1866-1874

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 < 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

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

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 1984;16:948-53

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

Humphrey perimetry in patients with suprasellar mass

Ahmed et al. Neuroradiologic screening in normal-pressure glaucoma: study results and literature review. J Glaucoma. 2002 Aug;11(4):279-86

NTG and Neuroimaging Some physicians routinely obtain

neuroimaging studies in patients with NTG

Cost-to-benefit ratio of performing such studies is unknown

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 Aug;11(4):279-86

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

NTG and Neuroimaging In Bianchi-Marzoli at al’s 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 1995;102:436-440.

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

NTG: Who needs neuroimaging?

Atypical rate of progression of VF loss Monocular or binocular

Pallor > cupping Asymmetric cupping

Especially if progressive changes while IOP remains symmetric and well controlled

NTG: Who needs neuroimaging?

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