Which type of glaucoma can occur with normal intraocular pressure?

• A. Acute angle-closure glaucoma
• B. Normal tension glaucoma
• C. Secondary glaucoma from trauma
• D. Congenital glaucoma

Answer: (B)

Normal tension glaucoma shows that optic nerve damage can occur even when the eye’s internal pressure is in the normal range. In this condition, the IOP readings stay within what we consider typical limits (often around or below 21 mmHg on repeated checks), yet the optic nerve slowly develops cupping and the visual field narrows. The important idea is that high IOP is a major risk factor for glaucoma, but it isn’t required for damage to occur; other factors—such as vulnerability of the optic nerve, vascular regulation, and ocular blood flow—can make the nerve susceptible even at normal pressures.

This is different from acute angle-closure glaucoma, which presents with a sudden, very high IOP and acute symptoms; congenital glaucoma, which appears in infancy with characteristic eye changes; and trauma-related secondary glaucoma, which usually involves pressure changes due to injury to the drainage angle or other eye structures and often results in elevated IOP as part of its course. In normal tension glaucoma, the emphasis is on detecting optic nerve damage and visual field loss with normal IOP, and management focuses on reducing risk of progression, sometimes aiming for an IOP lower than the patient’s measured baseline.