Normal Tension Glaucoma: Who Needs Neuroimaging?

1. Normal Tension Glaucoma:Who 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

3. 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

4. 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

5. Nonglaucomatous optic disc cupping • Compressive lesion • Meningioma • Aneurysm • Dolichoectasia of the internal carotid artery • Suprasellar mass

6. 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

7. Glaucomatous VS Nonglaucomatous cupping • Systematic approach recommended • Demographic characteristics • Visual acuity • Optic disc characteristics • Visual field findings

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

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

15. 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

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

17. 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.

18. 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

19. 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

20. NTG: Who needs neuroimaging? • Most likely NTG if: • Vertical elongation of the cupping • Presence of notch • Presence of splinter hemorrhage • Family history of glaucoma