Illustration of an eye with subtle light on optic nerve, symbolizing hidden pressure in glaucoma.

Normal Eye Pressure, Hidden Danger: Are You at Risk for Silent Glaucoma?

Jordan Keane in Health & Wellness August 2025 • 4 min read.

"The Shocking Prevalence of Normal-Tension Glaucoma and How to Protect Your Sight"

Glaucoma, a leading cause of irreversible blindness, is often associated with elevated intraocular pressure (IOP). However, a significant portion of glaucoma cases, known as normal-tension glaucoma (NTG) or primary angle closure glaucoma (PACG), occurs even when eye pressure readings fall within the normal range. This silent threat can lead to delayed diagnosis and potentially devastating vision loss.

A recent study published in the 'Journal of Glaucoma' sheds light on the prevalence of PACG with normal IOP, exploring the unique ocular characteristics of individuals affected by this condition. The research underscores the importance of comprehensive eye exams that go beyond simple pressure checks to identify those at risk.

The study reveals surprising statistics about the occurrence of normal-pressure PACG, particularly in Asian populations, and highlights key factors that can help clinicians detect this hidden form of glaucoma early. Understanding these risk factors and the role of advanced diagnostic techniques is crucial for preserving vision.

What is Normal-Tension Glaucoma and Why Is It So Hard to Detect?

Illustration of an eye with subtle light on optic nerve, symbolizing hidden pressure in glaucoma.

Normal-tension glaucoma (NTG), also known as normal-pressure glaucoma, is a type of glaucoma where damage to the optic nerve occurs despite having IOP within the statistically normal range. It is a challenge to detect, as the main risk factor traditionally associated with glaucoma, high eye pressure, is absent. This can lead to delayed diagnosis and progression of the disease before it is discovered.

Several factors may contribute to the development of NTG, even with normal IOP. These include:

Optic Nerve Vulnerability: Some individuals may have optic nerves that are more susceptible to damage, even at normal pressure levels.
Blood Flow Issues: Problems with blood flow to the optic nerve can contribute to nerve damage. Conditions like low blood pressure or vasospasm (narrowing of blood vessels) may play a role.
Anatomical Factors: Specific anatomical characteristics of the eye, such as the depth of the anterior chamber, can influence the risk of developing NTG.
Systemic Conditions: Certain systemic diseases, such as autoimmune disorders, have been linked to an increased risk of NTG.

Because of these varied factors, relying solely on IOP measurements can be misleading. Comprehensive eye exams that include assessment of the optic nerve, visual field testing, and potentially imaging of the nerve fibers are essential for early detection of NTG.

Take Control of Your Eye Health Today

Don't let normal eye pressure lull you into a false sense of security. If you have any risk factors for glaucoma, such as a family history of the disease, or are of Asian descent, make sure to discuss your concerns with your eye doctor. Early detection and management are key to preserving your sight for years to come.

About this Article -

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Everything You Need To Know

What is normal-tension glaucoma (NTG), and why is it considered a 'silent threat' to vision?

Normal-tension glaucoma (NTG), also known as normal-pressure glaucoma, is a type of glaucoma where optic nerve damage occurs despite intraocular pressure (IOP) being within the normal range. It's a 'silent threat' because the absence of high eye pressure, traditionally associated with glaucoma, can lead to delayed diagnosis. This delay allows the disease to progress, causing potentially irreversible vision loss before it's discovered. Unlike glaucoma typically linked to elevated IOP, NTG presents a diagnostic challenge, requiring comprehensive eye exams beyond standard pressure checks.

Besides elevated intraocular pressure (IOP), what other factors can contribute to the development of normal-tension glaucoma (NTG)?

Several factors beyond elevated intraocular pressure (IOP) can contribute to normal-tension glaucoma (NTG). These include optic nerve vulnerability, where some individuals' optic nerves are more susceptible to damage even at normal pressure levels. Blood flow issues to the optic nerve, influenced by conditions like low blood pressure or vasospasm, can also play a role. Anatomical factors, such as the depth of the anterior chamber, and systemic conditions, such as autoimmune disorders, are other contributing factors. Considering these varied elements is crucial since relying solely on IOP measurements for diagnosis can be misleading.

The study mentioned research from the 'Journal of Glaucoma'. What was the focus of this research and why is it significant?

The study published in the 'Journal of Glaucoma' sheds light on the prevalence of primary angle closure glaucoma (PACG) with normal intraocular pressure (IOP). This research is significant because it emphasizes the importance of comprehensive eye exams that go beyond simple pressure checks to identify individuals at risk for this hidden form of glaucoma. The study reveals statistics about the occurrence of normal-pressure PACG, particularly in Asian populations, and highlights key factors that can help clinicians detect this condition early, underscoring the need for advanced diagnostic techniques to preserve vision.

If intraocular pressure (IOP) is within a normal range, what specific tests should be included in a comprehensive eye exam to detect normal-tension glaucoma (NTG)?

If intraocular pressure (IOP) is within a normal range, a comprehensive eye exam to detect normal-tension glaucoma (NTG) should include several key assessments. These include a thorough evaluation of the optic nerve to identify any signs of damage. Visual field testing is essential to detect any peripheral vision loss, which is a common symptom of glaucoma. Additionally, imaging of the nerve fibers, such as Optical Coherence Tomography (OCT), can provide detailed information about the structure and health of the optic nerve. These tests, beyond standard IOP measurements, are crucial for early and accurate diagnosis of NTG.

What are the implications of normal-tension glaucoma (NTG) often being undetected, and what proactive steps can individuals take to safeguard their vision?

The implications of undetected normal-tension glaucoma (NTG) are potentially devastating, as delayed diagnosis can lead to irreversible vision loss. Because NTG progresses without the warning sign of high intraocular pressure (IOP), individuals may not realize they have the condition until significant damage has occurred. To safeguard vision, individuals, especially those with risk factors such as a family history of glaucoma or those of Asian descent, should proactively discuss their concerns with an eye doctor. Regular, comprehensive eye exams that include assessments of the optic nerve and visual fields are crucial for early detection and management of NTG.