Patients with what type of glaucoma have optic nerve cupping and visual field loss despite normal IOP?

• A. Open-angle glaucoma
• B. Low tension glaucoma
• C. Angle-closure glaucoma
• D. Uveitic glaucoma

Answer: (B)

The situation being tested is that glaucoma can cause optic nerve damage even when eye pressure is in the normal range. This is normal tension glaucoma, also called low tension glaucoma. In these eyes, the optic nerve is susceptible to damage or there are vascular factors that reduce blood flow to the nerve, so cupping of the optic nerve and progressive visual field loss occur despite IOP remaining within what’s considered normal (typically up to about 21 mmHg).

The other glaucoma types usually involve higher intraocular pressure or a secondary mechanism: open-angle glaucoma commonly features elevated pressure though not always, angle-closure glaucoma involves a blockage that raises IOP acutely, and uveitic glaucoma stems from intraocular inflammation affecting drainage and pressure regulation.