Normal Tension Glaucoma: Causes, Symptoms, Treatment, and More

Glaucoma steals sight silently. Many assume high eye pressure is the culprit, but that’s not always true. Normal tension glaucoma damages the optic nerve despite normal pressure levels. Without timely detection, vision loss can be significant. 

What Is Normal Tension Glaucoma?

Glaucoma is an eye disease that damages the optic nerve. It is the crucial link between the eye and brain. This nerve transmits visual signals, allowing sight. In most cases, high intraocular pressure (IOP)—the pressure inside the eye—triggers damage. However, normal tension glaucoma occurs even when IOP stays within the normal range.

The exact cause remains uncertain. Experts believe vascular dysregulation and genetic predisposition may play a role. Conditions that affect blood circulation to the optic nerve could contribute. Since vision loss develops gradually, many remain unaware until it’s severe. Routine eye exams help catch it early.

Causes of Normal-Tension Glaucoma

The exact cause of normal tension glaucoma remains unclear. Unlike other types of glaucoma, it occurs without high eye pressure. However, researchers believe several factors may contribute to optic nerve damage.

1. Poor blood circulation: Reduced blood supply may deprive the optic nerve of oxygen and nutrients, leading to gradual deterioration.
2. Vascular disorders: Conditions like migraines, Raynaud’s disease, obstructive sleep apnoea (OSA), and low blood pressure can affect the blood supply to the optic nerve.
3. Structural optic nerve weakness: Some people naturally have fragile optic nerves, making them more vulnerable to damage, even with normal eye pressure.
4. Genetics: Family history plays a role in increasing the likelihood of developing this condition.

Symptoms of Normal-Tension Glaucoma

Normal tension glaucoma progresses without much noise. It doesn’t cause noticeable discomfort or sudden vision changes. So, by the time normal tension glaucoma symptoms appear, significant damage can often occur. Below are some symptoms.

• Gradual vision loss: Blind spots may develop, often starting with paracentral vision before affecting peripheral or central sight.
• Difficulty seeing in dim light: Reduced contrast sensitivity makes it harder to adjust between light and dark environments.
• Blurred or distorted vision: Objects may appear less sharp or slightly warped over time.
• Eye strain or fatigue: Some experience mild discomfort, especially after reading or screen use.

Because symptoms emerge late, routine eye check-ups are essential. Early detection helps slow normal tension glaucoma progression rate and preserve vision.

Normal Tension Glaucoma Risk Factors

Some people are more likely to develop normal-tension glaucoma, even with normal eye pressure. Age is a key factor, with those over 60 facing higher risks. Studies suggest a stronger link in individuals of Asian descent.

Genetics also play a role. If a close family member has glaucoma, the chances of developing this condition increase. Another significant factor is thin corneas. Although a thinner-than-average cornea may cause IOP readings to appear lower than they actually are, it is also linked to increased susceptibility to optic nerve damage.

Lifestyle and overall health matter, too. Poor sleep patterns, chronic stress, and vascular conditions like Raynaud’s disease and obstructive sleep apnoea (OSA) can indirectly affect eye health. Since normal tension glaucoma risk factors often overlap, regular eye exams remain the best defence against vision loss.

Diagnosis of Normal Tension Glaucoma

An ophthalmologist examines the optic nerve using optical coherence tomography (OCT) or a dilated eye examination. These methods reveal early signs of nerve thinning. 

Visual field tests check for blind spots, while corneal thickness measurements ensure accurate pressure readings. Although abnormalities in blood flow to the optic nerve are suspected contributors, there is no standard clinical test for measuring optic nerve circulation in routine practice.

Because normal tension glaucoma symptoms appear late, routine screenings are essential. Nethradhama Super Speciality Eye Hospital offers state-of-the-art diagnostic tools for early detection and personalised care.

Treatment Options for Normal Tension Glaucoma

Normal tension glaucoma treatment focuses on protecting the optic nerve and slowing vision loss. Since eye pressure is not always high, doctors take a multi-step approach based on disease severity.

Medications for Normal-Tension Glaucoma

Doctors often prescribe normal tension glaucoma treatment in the form of medicated eye drops. These reduce intraocular pressure slightly, even if it’s already within normal limits. Lowering pressure helps slow optic nerve damage and prevents further vision loss. Some medications, such as brimonidine, may have neuroprotective benefits beyond IOP reduction. In certain cases, oral medications may be added for better control. Side effects vary, so regular monitoring is necessary. Patients should never stop using prescribed drops without consulting their doctor. 

Laser Treatment for Normal-Tension Glaucoma

Laser therapy offers a non-invasive way to manage normal tension glaucoma when medications alone are not enough. The procedure helps lower eye pressure slightly, reducing stress on the optic nerve. While pressure isn’t always the main cause, even minor reductions can slow the disease’s progression. 

Selective Laser Trabeculoplasty (SLT) is a common option, but it is less effective in NTG than in other types of glaucoma. It improves fluid drainage from the eye, but since NTG is not primarily pressure-driven, SLT’s success varies. The procedure is quick, painless, and performed in a clinic. Though results differ, some patients experience long-term benefits. 

Surgical Options for Normal Tension Glaucoma

When medications and laser treatments fail to control normal tension glaucoma, surgery may be necessary. The goal is to improve fluid drainage from the eye, reducing pressure fluctuations that could worsen optic nerve damage. Even small reductions in pressure can help slow disease progression.

Trabeculectomy is a common procedure where a tiny opening is created to help fluid drain more efficiently. In some cases, drainage implants are used instead. While surgery carries some risks, it offers long-term benefits for patients with worsening vision loss. 

Can Normal Tension Glaucoma Be Prevented?

There is no guaranteed way to prevent normal tension glaucoma, but early detection and lifestyle adjustments can help reduce risks. Since the disease progresses silently, routine eye exams remain the best defence. 

Maintaining stable blood pressure is essential, as fluctuations can impact optic nerve health. A balanced diet, regular exercise, and proper sleep also support overall eye function. Avoiding smoking, managing vascular health, and reducing stress may further protect nerve health. 

Conclusion

Normal tension glaucoma is a silent threat to vision. It progresses without obvious warning signs, making early detection crucial. Since eye pressure stays within normal limits, many people remain unaware until significant damage has occurred. Regular eye exams are the best way to catch it early and start treatment.

Though there’s no cure, various treatments help slow progression. Medications, laser therapy, and surgery offer effective options when necessary. Lifestyle changes, such as managing blood pressure, improving vascular health, and reducing stress, may also support optic nerve function.