Glaucoma refers to a group of eye disorders often associated with a dangerous buildup of internal eye pressure, known as intraocular pressure (IOP). This increased pressure can damage the optic nerve, which carries visual information from the eye to the brain.

If left untreated, most types of glaucoma gradually worsen and can lead to permanent visual damage and eventually blindness. The damage caused by glaucoma is usually irreversible. Because the disease often progresses silently without obvious warning signs, glaucoma is frequently referred to as the “silent blinding disease” or the “sneak thief of sight.”

Globally, glaucoma is the second most common cause of blindness. It is estimated that about 4.5 million people worldwide are blind due to glaucoma, and this number may increase significantly in the coming years.

One of the major concerns with glaucoma is that it often develops without symptoms in its early stages. Studies suggest that up to 50% of affected individuals in developed countries are unaware they have glaucoma, and this number may reach 90% in underdeveloped regions.

In India, glaucoma contributes to about 12.8% of total blindness and is considered the third most common cause of blindness. The prevalence of glaucoma in the country ranges between 2.6% and 4.1%. With the ageing population increasing rapidly, the number of people affected is also expected to rise.

Risk Factors for Glaucoma

Early detection is extremely important because glaucoma can be successfully managed if diagnosed early. While anyone can develop glaucoma, certain individuals are at higher risk and should undergo regular eye examinations.

Major risk factors include:

Family history of glaucoma

Black racial ancestry

 History of elevated intraocular pressure

 Nearsightedness (high degree of myopia)

 Previous injury to the eye

 Long-term use of cortisone or steroid medications (either eye drops or systemic medications)

Individuals with these risk factors should undergo more frequent eye examinations.

There are several different types of glaucoma. Most cases, however, fall into two main categories:

This is the most common type. It develops slowly over time and is considered a chronic condition. In most cases, patients do not experience symptoms in the early stages.

Closed-Angle (Angle-Closure) Glaucoma

This form can develop suddenly and may cause acute symptoms. It requires immediate medical attention. Glaucoma usually affects both eyes, although one eye may deteriorate more rapidly than the other.

Glaucoma may develop in one or both eyes.

The most common type, open-angle glaucoma, usually produces no symptoms in the early stages. It causes no pain, and vision may initially appear normal.

However, if untreated, patients gradually lose their peripheral (side) vision. People often describe this as looking through a tunnel. Over time, even the central vision may decrease until severe visual loss occurs. Because symptoms appear late, many patients remain unaware of the disease until significant vision loss has already occurred.

Tests Used for Diagnosing Glaucoma

Glaucoma is detected through a comprehensive eye examination that may include the following tests:

 Visual acuity test – measures how clearly you see.

 Dilated eye examination – allows the doctor to examine the optic nerve.

 Gonioscopy – evaluates the drainage angle of the eye.

 Tonometry – measures intraocular pressure (IOP).

 Pachymetry – measures corneal thickness.

 Visual field testing – detects loss of peripheral vision.

Additional advanced imaging methods may also be used to monitor glaucoma, including:

 Scanning Laser Polarimetry (SLP)

 Optical Coherence Tomography (OCT)

 Confocal Scanning Laser Ophthalmoscopy

These technologies help assess damage to the optic nerve and detect progression of the disease.

How Often Should Eye Screening Be Done?

The American Academy of Ophthalmology recommends the following screening intervals:

People with African ancestry or a family history of glaucoma should have an eye exam every two to four years. Others should have at least two eye exams during this period.

Eye examination every two to four years.

Age 65 years or older

Eye examination every one to two years.

Regular screening is important because glaucoma often develops without symptoms in its early stages. Once the optic nerve is damaged, the vision loss cannot be reversed. Early detection therefore plays a crucial role in preserving vision.

Treatment of Glaucoma

Treatment depends on the severity of the disease and may include:

 Eye drops (medications) to lower eye pressure

 Surgical procedures

In most cases, treatment begins with medicated eye drops designed to reduce intraocular pressure.

Since glaucoma often does not cause pain or noticeable symptoms, some patients become careless about using their prescribed medications. However, poor adherence to treatment is one of the leading causes of blindness due to glaucoma.

Patients should understand that glaucoma is usually a lifelong condition. Regular follow-up visits and strict adherence to prescribed medications are essential to preserve vision. Although there is no permanent cure for glaucoma, medications, laser therapy, or surgery can slow or stop further vision loss.

How Can You Reduce the Risk of Blindness?

Glaucoma-related blindness can often be prevented with proper treatment and regular monitoring.

Important steps include:

 Using medications exactly as prescribed

 Attending regular follow-up visits with the eye doctor

 Monitoring intraocular pressure several times a year

 Performing visual field tests at least once annually

 Taking photographs or imaging of the optic nerve every one to two years

Some visits may involve only quick pressure checks, while others may include comprehensive examinations and imaging tests. You can also help protect the vision of family members who may be at high risk of glaucoma. Encourage relatives and friends—especially those over 40 years of age or with a family history of glaucoma—to undergo annual eye examinations with dilated pupils.

Early diagnosis and regular follow-up remain the most effective ways to prevent vision loss from glaucoma.

Prof. (Dr) Bashir Ahmad is a Director,

Eye Care And Research Centre

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