Which condition is characterized by optic neuropathy with normal intraocular pressure?

• A. Low-tension glaucoma
• B. Primary open-angle glaucoma
• C. Acute angle-closure glaucoma
• D. Diabetic retinopathy

Answer: (A)

Low-tension (normal-tension) glaucoma is the condition where optic nerve damage and glaucomatous visual field loss occur even when intraocular pressure readings are within the normal range. The key idea is that the optic nerve can be susceptible to injury at normal pressures, so damage happens without the IOP being elevated. This is why you see classic glaucomatous signs—optic disc cupping and neuroretinal rim thinning with corresponding visual field defects—despite a normal IOP.

Think of it in terms of risk factors beyond sheer pressure: vascular factors, nocturnal blood pressure dips, and impaired optic nerve perfusion can contribute to damage. Management focuses on lowering IOP further to protect the optic nerve, even if the starting pressure is normal, using medications, laser therapy, or surgery as needed.

For comparison, acute angle-closure glaucoma presents with very high IOP and acute symptoms; diabetic retinopathy involves retinal vascular changes rather than optic neuropathy linked to IOP. Primary open-angle glaucoma typically involves elevated IOP, though some patients may have normal pressures; the defining feature here is glaucomatous damage associated with high or fluctuating IOP, not necessarily at normal levels.