Normal Tension Glaucoma (NTG).

Normal tension glaucoma is also known as low-tension glaucoma or normal pressure glaucoma. In this type of glaucoma, the optic nerve is damaged even though intraocular pressure (IOP) is not very high. Doctors do not know why some people’s optic nerves suffer damage even though pressure levels are in the “normal” range (between 12-22 mm Hg).

Those at higher risk for this form of glaucoma are people with a family history of normal tension glaucoma, people of Japanese ancestry, and people with a history of systemic heart disease, such as irregular heart rhythm. Normal tension glaucoma is usually detected after an examination of the optic nerve.

The Glaucoma Research Foundation sponsored a collaborative international study to help determine the best treatment for this type of glaucoma. The study concluded that eye drops used to lower intraocular pressure were effective even in cases of normal tension glaucoma. Currently, most doctors treat normal tension glaucoma by keeping normal eye pressures as low as possible with medicines, laser surgery, or filtering surgery.