eMedicine Specialties > Ophthalmology > Intraocular Pressure

Glaucoma, Low Tension: Differential Diagnoses & Workup

Author: Jacqueline Freudenthal, MD, Co-Investigator, Ophthalmic Consultants Centre, Toronto
Coauthor(s): Iqbal Ike K Ahmed, MD, FRCSC, Clinical Assistant Professor, Department of Ophthalmology, University of Utah; Baseer U Khan, MD, Staff Physician, Department of Ophthalmology, University of Toronto, Canada; Khalid Hasanee, MD, Glaucoma and Anterior Segment Fellow, Department of Ophthalmology, University of Toronto
Contributor Information and Disclosures

Updated: Jan 29, 2010

Differential Diagnoses

Central Retinal Artery Occlusion
Optic Neuritis, Adult
Glaucoma, Angle Closure, Acute
Optic Neuropathy, Anterior Ischemic
Glaucoma, Angle Closure, Chronic
Optic Neuropathy, Compressive
Glaucoma, Drug-Induced
Posner-Schlossman Syndrome
Glaucoma, Pigmentary
Sarcoidosis
Glaucoma, Primary Open Angle
Toxic/Nutritional Optic Neuropathy
Glaucoma, Uveitic

Other Problems to Be Considered

Intermittent intraocular pressure (IOP) elevation
Burned-out glaucoma
Nonglaucomatous optic nerve
Congenital disc anomalies/cupping
Myopia with peripapillary atrophy
Optic nerve coloboma/pit
Vascular etiology
Carotid and ophthalmic artery occlusion
Previous blood loss or shocklike episode
Neurologic etiology
Hereditary optic neuropathy
Leber optic atrophy
Dominant or recessive optic atrophy
Tonometric error (thin cornea)

Workup

Laboratory Studies

  • Blood tests in low-tension glaucoma (LTG) 
    • Order a CBC count to rule out anemia.
    • Erythrocyte sedimentation rate (ESR) rarely is elevated in low-tension glaucoma and typically is obtained in cases of decreased central acuity with a pale nerve to rule out anterior ischemic optic neuropathy (AION).
    • Order rapid plasma reagent (RPR) and fluorescein treponema antibody (FTA) testing.
    • Checking for the presence of antinuclear antibody (ANA) is recommended to rule out collagen-vascular and autoimmune diseases. Screening for extractable nuclear antigens (ie, Ro, La, Sm) also is recommended to rule out autoimmune diseases.
    • Serum immunofixation for monoclonal gammopathy is indicated. Approximately 10% of patients with low-tension glaucoma have monoclonal gammopathy (paraproteinemia), which represents a benign condition two thirds of the time. However, lymphoproliferative disorders (ie, cancers) need to be ruled out by a hemato-oncology specialist if results from this test are positive.
    • High-sensitivity C-reactive protein is becoming the criterion standard for documenting both symptomatic and nonsymptomatic ischemic heart disease, and results often are positive in patients with low-tension glaucoma.
    • Mitochondrial testing for Leber should be ordered, when indicated.
    • Anticardiolipin antibody (ACA) testing should be performed, and an increased level is considered a risk factor for visual-field defect progression.9

Imaging Studies

  • Optic nerve head and/or retinal nerve fiber analysis may be helpful in diagnosing and monitoring progression of glaucomatous optic neuropathy. 
    • Analyze optic nerve head with confocal scanning laser ophthalmoscopy (SLO), eg, Heidelberg Retinal Tomograph, or optical coherence topography (OCT).
    • Analyze retinal nerve fiber with confocal SLO, OCT, or scanning laser polarimetry (GDx). Often, retinal nerve fiber layer changes may occur before any changes on visual-field testing. Most often, nerve fiber layer thinning occurs first in the superior and inferior poles.
  • Neuroimaging of orbits and head 
    • MRI is the preferred imaging modality compared with CT scanning because of its higher sensitivity.
    • Controversy exists as to whether neuroimaging should be performed routinely. Some advocate referral to a neurophthalmologist if concerned.
    • Neuroimaging should be performed in any patient with the following:
      • Markedly asymmetric disease
      • Increased optic disc pallor relative to cupping
      • Unusual visual-field defects, particularly those with respect to the vertical midline
      • Rapid progression of visual fields
      • Rapid progression of optic neuropathies
      • Dyschromatopsia
      • Afferent papillary defect with mild cupping
  • If indicated, carotid Doppler testing is recommended to rule out carotid insufficiency.
  • When indicated, chest radiography is necessary to rule out sarcoidosis.

Other Tests

  • To rule out nocturnal hypotension, 24-hour ambulatory blood pressure monitoring is advised.
  • The diurnal tension curve may need to be determined. Although IOP may be normal during an examination, the patient may have intermittent spikes in IOP throughout the day that may explain optic nerve and visual field damage.
  • Multifocal electroretinograms (mfERGs) provides an index of identification for a glaucomatous optic neuropathy in normal-tension glaucoma.10
  • Future diagnostic modalities - Ocular blood flow analysis 
    • Scanning laser ophthalmoscopy - Retinal and choroidal, superficial optic nerve head
    • Doppler ultrasonography - Carotid arteries
    • Confocal scanning laser Doppler flowmetry (Heidelberg Retinal Flowmetry) - Short posterior ciliary artery circulation, optic nerve head
    • Diffuse tension MRI (DTI) - Reduction of the optic radiation volume in patients with normal-tension glaucoma, in relation to arterial hypertension and cerebral microangiopathy stage11

Histologic Findings

  • Findings include posterior deformation of the cribriform plate, with compression of the lamina due to direct deformation by secondary vascular compression, resulting in glial atrophy.

More on Glaucoma, Low Tension

Overview: Glaucoma, Low Tension
Differential Diagnoses & Workup: Glaucoma, Low Tension
Treatment & Medication: Glaucoma, Low Tension
Follow-up: Glaucoma, Low Tension
References
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References

  1. Kim KCY, Ahn AMD, Seong SGJ. Does redefining of high intraocular pressure (IOP) according to IOP distribution change prevalence of normal tension glaucoma in Korea? [abstract]. World Glaucoma Congress, 2009. Available at http://www.worldglaucoma.org/WGC2009/. Accessed July 24, 2009.

  2. Caprioli J, Coleman AL. Intraocular pressure fluctuation a risk factor for visual field progression at low intraocular pressures in the advanced glaucoma intervention study. Ophthalmology. Jul 2008;115(7):1123-1129.e3. [Medline].

  3. Paul T, Radcliffe N, Shimmio M. Reclassification of normal and high tension glaucoma eyes using corneal compensated IOP [abstract]. World Glaucoma Congress, 2009. Available at http://www.worldglaucoma.org/WGC2009/. Accessed July 28, 2009.

  4. Akopov E, Astakhov Y, Nefedova D. Retinal vessels calibrometry in normal pressure glaucoma evaluation [abstract]. World Glaucoma Congress, 2009. Available at http://www.worldglaucoma.org/WGC2009/. Accessed July 28, 2009.

  5. Su WW, Cheng ST, Hsu TS, Ho WJ. Abnormal flow-mediated vasodilation in normal-tension glaucoma using a noninvasive determination for peripheral endothelial dysfunction. Invest Ophthalmol Vis Sci. Aug 2006;47(8):3390-4. [Medline].

  6. Delaney Y, Walshe TE, O'Brien C. Vasospasm in glaucoma: clinical and laboratory aspects. Optom Vis Sci. Jul 2006;83(7):406-14. [Medline].

  7. Plange N, Kaup M, Remky A, Arend KO. Prolonged retinal arteriovenous passage time is correlated to ocular perfusion pressure in normal tension glaucoma. Graefes Arch Clin Exp Ophthalmol. Aug 2008;246(8):1147-52. [Medline].

  8. Harris A, Siesky B, Zarfati D, et al. Relationship of cerebral blood flow and central visual function in primary open-angle glaucoma. J Glaucoma. Jan 2007;16(1):159-63. [Medline].

  9. Chauhan BC, Mikelberg FS, Balaszi AG, LeBlanc RP, Lesk MR, Trope GE. Canadian Glaucoma Study: 2. risk factors for the progression of open-angle glaucoma. Arch Ophthalmol. Aug 2008;126(8):1030-6. [Medline]. [Full Text].

  10. Asano E, Mochizuki K, Sawada A, Nagasaka E, Kondo Y, Yamamoto T. Decreased nasal-temporal asymmetry of the second-order kernel response of multifocal electroretinograms in eyes with normal-tension glaucoma. Jpn J Ophthalmol. Sep-Oct 2007;51(5):379-89. [Medline].

  11. Michelson G, Waerntges S, Engelhorn T, Doerfler A. Reduced optic radiation volume measured by DTI is correlated by arterial hypertension in normal tension glaucoma [abstract]. World Glaucoma Congress, 2009. Available at http://www.worldglaucoma.org/WGC2009/. Accessed July 28,2009.

  12. [Guideline] Screening for glaucoma: recommendation statement. US Preventive Services Task Force. National Guideline Clearinghouse. Mar 2005.

  13. [Guideline] Primary open-angle glaucoma. American Academy of Ophthalmology. National Guideline Clearinghouse. 2005.

  14. [Guideline] Comprehensive adult eye and vision examination. American Optometric Association. National Guideline Clearinghouse. 2005.

  15. Orgul S, Zawinka C, Gugleta K, Flammer J. Therapeutic strategies for normal-tension glaucoma. Ophthalmologica. Nov-Dec 2005;219(6):317-23. [Medline].

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  17. Netland PA, Chaturvedi N, Dreyer EB. Calcium channel blockers in the management of low-tension and open-angle glaucoma. Am J Ophthalmol. May 15 1993;115(5):608-13. [Medline].

  18. Takako Nakagami, Yoshio Yamazaki, Fukuko Hayamizu. Prognostic Factors for Progression of Visual Field Damage in Patients with Normal-Tension Glaucoma. Japanese Journal of Ophthalmology. January, 2006;Volume 50, Number 1:38-42.

  19. Abedin S, Simmons RJ, Grant WM. Progressive low-tension glaucoma: treatment to stop glaucomatous cupping and field loss when these progress despite normal intraocular pressure. Ophthalmology. Jan 1982;89(1):1-6. [Medline].

  20. Fraunfelder FT, Roy FH. Current Ocular Therapy. Philadelphia: WB Saunders; 2000:488-9.

  21. Hitchings RA. Low tension glaucoma--its place in modern glaucoma practice. Br J Ophthalmol. Aug 1992;76(8):494-6. [Medline].

  22. Kawabata K, Kimura T, Fujiki K, Murakami A. [Ocular pulse amplitude in patients with open-angle glaucoma, normal-tension glaucoma, and ocular hypertensionby dynamic observing tonometry]. Nippon Ganka Gakkai Zasshi. Dec 2007;111(12):946-52. [Medline].

  23. Stewart WC, Reid KK. Incidence of systemic and ocular disease that may mimic low-tension glaucoma. J Glaucoma. 1992;1:27-31.

  24. Werner E. Progressive normal-tension glaucoma. I. Analysis. J Glaucoma. Dec 1996;5(6):422-6. [Medline].

  25. ²Kurtz S, Haber I, Kesler A. Corneal Thickness Measurements in Normal-tension Glaucoma Workups: Is It Worth the Effort?. J Glaucoma. Apr 15 [Epub ahead of print] 2009.

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Further Reading

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Keywords

low-tension glaucoma, low tension glaucoma, LTG, low-pressure glaucoma, optic neuropathy, intraocular pressure, primary open-angle glaucoma, POAG

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Contributor Information and Disclosures

Author

Jacqueline Freudenthal, MD, Co-Investigator, Ophthalmic Consultants Centre, Toronto
Jacqueline Freudenthal, MD is a member of the following medical societies: American Academy of Ophthalmology, Association for Research in Vision and Ophthalmology, and Canadian Ophthalmological Society
Disclosure: Nothing to disclose.

Coauthor(s)

Iqbal Ike K Ahmed, MD, FRCSC, Clinical Assistant Professor, Department of Ophthalmology, University of Utah
Iqbal Ike K Ahmed, MD, FRCSC is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery, Canadian Ophthalmological Society, and Ontario Medical Association
Disclosure: Nothing to disclose.

Baseer U Khan, MD, Staff Physician, Department of Ophthalmology, University of Toronto, Canada
Baseer U Khan, MD is a member of the following medical societies: Canadian Ophthalmological Society
Disclosure: Nothing to disclose.

Khalid Hasanee, MD, Glaucoma and Anterior Segment Fellow, Department of Ophthalmology, University of Toronto
Khalid Hasanee, MD is a member of the following medical societies: Canadian Medical Association, Canadian Ophthalmological Society, and Ontario Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Neil T Choplin, MD, Adjunct Clinical Professor, Department of Surgery, Section of Ophthalmology, Uniformed Services University of Health Sciences
Neil T Choplin, MD is a member of the following medical societies: American Academy of Ophthalmology, American Glaucoma Society, Association for Research in Vision and Ophthalmology, and California Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Martin B Wax, MD, Clinical Professor, Department of Ophthalmology, University of Texas Southwestern Medical School; Vice President, Ophthalmology Research and Development, Head, Ophthalmology Discovery Research, Alcon Labs, Inc
Martin B Wax, MD is a member of the following medical societies: American Academy of Ophthalmology, American Glaucoma Society, and Society for Neuroscience
Disclosure: Alcon Labs Salary Employment

CME Editor

Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri
Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology
Disclosure: Nothing to disclose.

 
 
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