Glaucoma: Causes, Symptoms, Types & Tests

Glaucoma is a group of eye diseases that gradually damage the optic nerve, the vital link between your eye and your brain. Often called the “silent thief of sight,” glaucoma can progress without obvious symptoms until vision loss becomes noticeable and irreversible. Early detection through routine eye exams is critical, as prompt treatment can help slow or prevent further vision damage.

What is Glaucoma?

Glaucoma is an eye disorder characterized by damage to the optic nerve, typically linked to increased pressure inside the eye (intraocular pressure or IOP). The optic nerve carries visual information from the retina to the brain, and its health is essential for clear vision. While elevated eye pressure is a major risk factor, glaucoma can sometimes develop even with normal IOP levels. Over time, damage to the optic nerve leads to vision loss, starting from the peripheral (side) vision and progressing toward the center if untreated.

Causes of Glaucoma

Glaucoma develops when the drainage system in the eye (called the trabecular meshwork) becomes blocked or doesn’t work efficiently. This causes fluid (aqueous humor) to build up, increasing intraocular pressure and eventually damaging the optic nerve.

Key causes and risk factors include:

• Age: Risk increases significantly after age 40.
• Family history: Genetics plays a strong role; having a close relative with glaucoma raises your risk.
• High intraocular pressure (IOP): The most significant risk factor, though not the only one.
• Ethnicity: People of African, Asian, or Hispanic descent are at higher risk.
• Medical conditions: Diabetes, high blood pressure, and heart disease can increase risk.
• Eye injuries: Trauma to the eye can damage its drainage system.
• Prolonged use of corticosteroids: Especially eye drops, which can raise IOP.
• Thin corneas: People with thinner corneal tissue are at higher risk.

Though the exact cause of glaucoma isn’t always clear, these risk factors help doctors identify those who should be monitored closely.

Symptoms of Glaucoma

One of the challenging aspects of glaucoma is that it often develops slowly without noticeable symptoms in its early stages. Symptoms vary by type but may include:

• Gradual loss of peripheral (side) vision
• Tunnel vision (advanced stage)
• Blurred vision
• Severe eye pain (more common in acute angle-closure glaucoma)
• Halos around lights
• Redness in the eye
• Nausea and vomiting (with sudden increase in eye pressure)

Types of Glaucoma

Glaucoma isn’t a single disease; it includes several types. The main ones are:

Primary Open-Angle Glaucoma (POAG):

• The most common form.
• Occurs when the eye’s drainage system becomes partially blocked over time.
• Develops slowly and painlessly, gradually damaging vision.

Angle-Closure Glaucoma (also called Narrow-Angle or Acute Glaucoma):

• Occurs when the drainage angle in the eye becomes completely blocked suddenly.
• Leads to a rapid increase in eye pressure.
• Symptoms can include severe eye pain, nausea, blurred vision, and halos.
• This is a medical emergency and requires immediate treatment to prevent blindness.

Normal-Tension Glaucoma:

• Optic nerve damage occurs despite normal eye pressure.
• Cause is unclear, but it may relate to poor blood flow to the optic nerve.

Secondary Glaucoma:

• Develops as a complication of another eye condition, trauma, inflammation, or prolonged steroid use.

Congenital Glaucoma:

• Rare, present at birth.
• Caused by improper eye drainage system development.
• Symptoms include cloudy eyes, excessive tearing, and sensitivity to light.

Tests Used to Detect Glaucoma

Because early glaucoma often lacks noticeable symptoms, eye doctors rely on several specialized tests to diagnose and monitor it:

• Tonometry: Measures intraocular pressure.
• Ophthalmoscopy (Fundus Exam): Allows the doctor to examine the shape and color of the optic nerve.
• Perimetry (Visual Field Test): Tests peripheral vision to detect vision loss patterns.
• Gonioscopy: Examines the drainage angle to differentiate between open-angle and angle-closure glaucoma.
• Pachymetry: Measures corneal thickness, as thinner corneas may increase glaucoma risk.
• Optical Coherence Tomography (OCT): Provides detailed images of the optic nerve and retinal layers.

Conclusion

Glaucoma is a serious but often silent eye disease that can cause irreversible vision loss if left untreated. Since early stages typically have no symptoms, routine comprehensive eye exams are essential, especially for those at higher risk. Understanding the causes, knowing the different types, and being aware of the available diagnostic tests can empower individuals to act early. With timely treatment—ranging from medicated eye drops to laser therapy and surgery—many people with glaucoma can slow disease progression and maintain quality vision for years.

Frequently Asked Questions (FAQ’s)

What is glaucoma?
Glaucoma is a group of eye diseases that damage the optic nerve, often due to increased eye pressure.

Can glaucoma be cured?
No, glaucoma can’t be cured, but its progression can often be slowed or controlled with treatment.

Who is at higher risk for glaucoma?
People over 40, those with a family history of glaucoma, and individuals of African, Asian, or Hispanic descent.

Does glaucoma always cause symptoms?
No, most types develop slowly and painlessly, with no early symptoms.

How is glaucoma detected?
Through eye exams that include measuring eye pressure, visual field tests, and optic nerve imaging.

What happens if glaucoma is left untreated?
It can lead to permanent vision loss and even blindness.

Is glaucoma painful?
Most common types aren’t painful, but angle-closure glaucoma can cause severe eye pain and requires immediate treatment.

At what age should I start glaucoma screening?
It’s recommended to start by age 40, or earlier if you have risk factors like family history.