Normal tension glaucoma is a type of glaucoma that causes damage to the optic nerve even when the pressure within the eye is normal. The causes are unknown, but theories suggest decreased blood flow or weaknesses in the optic nerve. Risk factors include family history, cardiovascular disease, and Japanese descent. Treatment involves keeping intraocular pressure low with medication, laser, or filter surgery.
The high pressure inside the eye can damage the optic nerve, causing vision loss and eventually blindness. This condition is called glaucoma, and there are several specific types of glaucoma. Although all glaucomas cause damage to the optic nerve due to intraocular pressure, most forms of glaucoma cause increased pressure. Normal tension glaucoma, however, occurs when the pressure within the eyeball is within the normal range but still damages the optic nerve.
The causes of normal tension glaucoma are unknown. Vision loss is directly related to optic nerve damage, but it’s not clear why the nerve is damaged when the pressure is within the normal range. Normal intraocular pressure has a measure of 10-20 millimeters of mercury. An estimated one-third of glaucoma cases involve normal intraocular pressure.
This condition is characterized by progressive damage to the optic nerve. As the damage worsens, the field of vision narrows. Normal tension glaucoma is difficult to diagnose. Standard glaucoma tests are based on a constantly rising intraocular pressure. The diagnosis of normal tension glaucoma depends on a careful examination and tests of visual acuity.
Several theories have been proposed as to why the optic nerve is damaged by normal pressure in some cases. One theory suggests that decreased blood flow causes optic nerve cells to die from lack of oxygen and nutrients. Without the cells to carry nerve impulses to the brain, vision suffers. An alternative theory cites weaknesses in the optic nerve that leave the nerve particularly susceptible to pressure-related damage even when the pressure is within the normal range. Additionally, poor circulatory mechanisms could inhibit blood vessels from regulating pressure within the eye, leading to damage.
A few risk factors for normal tension glaucoma have been identified. Anyone with a family history of any type of glaucoma is considered to be at risk for all types of glaucoma. Women are at a higher risk than men. The presence of cardiovascular disease also increases a person’s risk. People of Japanese descent are particularly susceptible to the disease.
Damage to the optic nerve caused by any type of glaucoma is irreversible, so the goal of treatment is to prevent further damage. Treatment for normal tension glaucoma is to keep intraocular pressure as low as possible with medication. If medications are ineffective, you may need laser or filter surgery. In some people, however, maintaining normal intraocular pressure isn’t enough to prevent further damage. Damage to their optic nerves progresses regardless of low eye pressure.
Protect your devices with Threat Protection by NordVPN
