Glaucoma – A Silent Thief of Vision

Glaucoma is the leading cause of irreversible blindness worldwide.

In most cases, glaucoma causes painless loss of vision from the periphery leaving the central vision intact till late stages, after which complete irreversible blindness occurs. That’s why most patients with glaucoma are unaware of their condition till it is too late.

Photo by cottonbro on

World Glaucoma Week will be observed from 6th to 12th March 2022.

I will be writing 7 blogs about Glaucoma, covering one aspect of the disease in each of my posts.

Since today is the first day of the World Glaucoma Week, let me start by introducing you to the basic facts about this serious eye disease – Glaucoma.

What is Glaucoma?

Glaucoma is a group of eye diseases that are characterized by progressive damage to the optic nerve (the nerve at the back of your eye responsible for vision), visual field changes (loss of vision from the sides) and may or may not be associated with increased eye pressure.

What causes Glaucoma?

The exact cause of glaucoma is poorly understood. In most cases, glaucoma is associated with a raised eye pressure.

There is a clear fluid that circulates within our eyes, known as aqueous humor. A normal circulation of aqueous humor is essential to maintaining the integrity of our eyes, and to maintain optimum vision.

This video describes the normal circulation of aqueous humor within the eye

Any obstruction to the flow of aqueous humor in the eye leads to a build of pressure. Gradually this pressure is transmitted backwards where the optic nerve lies. This causes damage to the optic nerve and causes loss of vision.

What are the different types of Glaucoma?

Glaucoma can be classified in several ways. However the most common broad classification of glaucoma is done depending on what level the obstruction to aqueous humor occurs leading to rise in pressure.

  1. Open angle glaucoma
  2. Closed angle glaucoma (acute glaucoma)

Let me discuss these in detail

1. Open angle glaucoma

This is the most common type of glaucoma. In this type of glaucoma, the blockage to the aqueous humor circulation occurs at the trabecular meshwork. This type of glaucoma is painless, and the vision loss occurs slowly, therefore doesn’t present with any symptoms at early stages.

This video explains the disease process in a patient with open angle glaucoma.

2. Closed angle glaucoma

This type of glaucoma is less common and occurs in patients who have a narrow irido-corneal angle in their eyes. Under certain circumstances, the narrow angle becomes a closed angle and the eye pressure rises suddenly and causes painful loss of vision.

This video explains the disease process in a patient with closed angle glaucoma.

I will be writing a separate article this week, explaining in detail about closed angle glaucoma, also known as acute glaucoma.

Now I will proceed by describing only “Open Angle Glaucoma” as it is the most common type.

What are the symptoms of Open Angle Glaucoma?

In early stages, there are no symptoms of glaucoma, that is why it is called as “silent thief of vision”

The vision loss in glaucoma follows a typical pattern.

In early stages, there could be a few spots of blurred vision. Eventually, the vision loss starts occurring from the sides. Initially it is just a mild blurring, but as the disease advances, the severity of vision loss increases, severely restricting the patient’s field of vision.

In advanced stages, the patient is just left with “tunnel vision” due to severe visual field loss. And eventually even that is lost, leaving the patient in complete darkness.

This video will help you understand the pattern of vision loss in glaucoma.

Apart from vision loss, some patients may experience heaviness in their eyes due to a constantly elevated eye pressure.

How is Glaucoma diagnosed?

Most cases are diagnosed incidentally during routine eye checkup since there are no symptoms in early glaucoma.

For a diagnosis of clinical glaucoma to be made, your eye doctor will evaluate your eye pressure, your optic nerve and may advise a test for visual field changes.

How is visual field tested?

The test for assessing a person’s visual field is known as “perimetry”.

In this test, the patient will be seated in front of a machine known as a “perimeter” and asked to fixate on a central focus. A tiny light will flash on the sides of the central target, and the patient will be asked to press a button every time they see a light, without shifting their focus from the central target.

Visual field testing is an important tool to make the diagnosis of glaucoma and also used to monitor the progression of the disease.

How is Glaucoma treated?

There are three treatment options for glaucoma

  1. Eye pressure lowering medications
  2. Laser procedures
  3. Surgery
  4. Glaucoma drainage implants

Medications are often the first choice of treatment. Glaucoma medications once started need to be continued lifelong to preserve vision. The vision loss that has already occurred due to glaucoma is irreversible, but the existing vision can be preserved by complying with the treatment.

I will be discussing the details of glaucoma treatment in one of my upcoming blogs.

Photo by Yelena Odintsova on

Glaucoma is a serious and a distressing eye disease, but with early diagnosis and proper treatment, the patient’s precious vision can be saved, allowing them to live their life to the fullest.

If you have any questions, feel free to comment below or email me on

I’ll see you tomorrow in another blog about glaucoma, till then take good care of your eyes and stay healthy!

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