CITY CONDITIONS UPDATE: The Wills Eye Hospital building, staff, and patients have been safe during the protests in the City. We will continue to monitor the situation. Friday care will proceed as scheduled at 840 Walnut Street unless conditions change. Please contact your physician if you are unable to keep your appointment.

Normal Tension Glaucoma

Normal tension glaucoma, also referred to as low tension glaucoma or normal pressure glaucoma, is a type of open-angle glaucoma where damage to the optic nerve occurs without intraocular pressure falling outside of a normal range. This differs from other types of glaucoma, where damage to the optic nerve occurs due to heightened intraocular pressure. At this time, researchers are still not completely sure why or how normal tension glaucoma occurs.


It is important to understand that there is no normal intraocular pressure, and no one number for intraocular pressure is safe for everyone. Instead, there is an average pressure range and intraocular pressure may be elevated, within the average range, or lower than average. Studies done on large populations in the United States indicate that average intraocular pressure is between 15-16 mmHg and about 95% of people have an intraocular pressure between ten and 21.

As for the connection between normal tension glaucoma and primary open-angle glaucoma, people with average pressure glaucoma never get an elevated intraocular pressure where those with P.O.A.G. do present with elevated pressure levels.


While we still have a lot to learn about the causes behind low tension glaucoma, the current understanding is that damage to the optic nerve without elevated intraocular pressure is due to either reduced blood flow to the optic nerve or an optic nerve that is otherwise already susceptible to damage.

Low tension glaucoma can run in families, so a family history of this illness is considered to be a strong risk factor. Other low tension glaucoma risk factors include age, irregular blood flow to the optic nerve, diabetes, sleep apnea, Raynaud’s syndrome, migraines, and anatomical abnormalities of the structures around the optic nerve.


Not all individuals with low tension glaucoma experience symptoms, however, some may occur. These include:

  • Changes in blood pressure
  • Migraine headaches
  • Blurred vision
  • Stinging or itchy eyes

We encourage you to see a specialist right away if you are experiencing the symptoms above.


The most common diagnostic method used to identify low tension glaucoma is a type of glaucoma eye pressure test known as tonometry. This test measures intraocular pressure within each eye, with measurements taken at different times throughout the day since levels may change from hour to hour.

Other diagnostic tests for this illness include:

  • Slit lamp examination, which can identify other signs or symptoms of glaucoma
  • Pachymetry, to measure corneal thickness
  • Gonioscopy, to check the angle between the cornea and iris

Your physician will likely use multiple diagnostic tests.


Treatments for normal pressure glaucoma are focused on manually lowering eye pressure, and may include:

  • Laser treatments
  • Conventional surgery
  • Medications

Sometimes it is also advised that patients stop taking certain currently prescribed medications.

Contact us today at Wills Eye Hospital for eye pressure testing and low tension glaucoma treatments. If you are experiencing any of the acute symptoms mentioned above, it is advised that you seek medical assistance as soon as possible.


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