Glaucoma Overview

When you suffer from any disease that affects your eyesight, it can be a daunting process to get to the bottom of what’s really going on. You often take your sight for granted until a serious disease threatens to take your vision away. Glaucoma is a set of eye diseases which can gradually and unknowingly become worse over your lifetime. In rarer cases it can affect your vision by way of sudden attack. So exactly what is glaucoma, and how can you avoid becoming a victim of this increasingly common disease?

Glaucoma is a set of eye diseases that can lead to blindness if left untreated. The common cause of glaucoma is a build-up of pressure in the eye, often when excess fluid becomes blocked. This fluid is known as aqueous fluid. Because of ongoing pressure from this built-up fluid, the sensitive optic nerve, which is located at the back of the eye can become damaged and may lead to irreversible blindness.

The optic nerve is important, as it’s made up of over one million nerve fibers, which help to send information to the brain about the images we see. What’s challenging about glaucoma is that there are usually no symptoms to suggest its presence. At least not until it may be too late to save your vision.   

Approximately three million Americans suffer from glaucoma, but because of the lack of symptoms, over half of those with glaucoma won’t even know they have it. Globally, over 60 million people have glaucoma and many have no clue. Glaucoma is the second leading cause of blindness, behind cataracts.

The two main types of glaucoma are described in terms of angles, as this is the angle between the iris (colored part of the eye) and the cornea (the clear part of your eye). While there are multiple types of glaucoma, the two main types are open and closed angle.

Open angle glaucoma

This is the most common type of glaucoma, which makes up 90% of all cases. It is a disease that develops slowly over time and can remain entirely asymptomatic until the disease has become quite developed. It can sneak up on you over a number of years, which is why it is known as the silent thief of sight.

Open angle glaucoma is where your drainage canals become blocked due to the angle where your iris and cornea meet not being as open or wide as seen in a healthy eye.  This blockage causes the eye pressure to rise, and damage to be caused to the optic nerve.

Angle closure glaucoma

This type of glaucoma can come with a sudden onset of symptoms, that requires immediate medical attention to save your sight. Chronic versions of angle closure glaucoma however can also develop without any symptoms.

The outer edge of the iris is known to bunch over the drainage canals, completely blocking the canal and preventing the fluid in your eye from draining. This type of glaucoma is a rarer form than open angle glaucoma.

Glaucoma: Causes & Warning Signs

It is estimated that approximately 10 to 33% of those with open angle glaucoma have inherited certain types of mutations in their genes from their parents. In particular, a gene called the MYOC gene, which gives instructions for the production of myocilin, a type of protein that is found in parts of the eye.

When mutations occur, there can be excess protein formation, which stops the free-flowing movement of fluid to and from the eye. This is because the body continues to produce fluid to keep the eyes hydrated, but it cannot properly drain from the eye.

In a healthy eye, fluid should leave the eye through what is called a trabecular meshwork, which can be viewed as a small pipeline for the fluid to exit.  

When fluid does not drain so freely, this causes a lot of pressure within the eye and leads to damage within the optic nerve. This damage is often irreversible, as the optic nerve has been robbed of nutrients and oxygen over a lengthy period of time. For this reason, early intervention is crucial.

Warning signs of open angle glaucoma

Unfortunately, there are no warning signs or symptoms with this predominant form of glaucoma. Because this type of glaucoma develops slowly over time, those that suffer from it don’t usually notice a loss of vision until the disease is quite developed. Open angle glaucoma can progress over many years without any noticeable symptoms.

The typical characteristics of open angle glaucoma is the gradual loss of peripheral (side vision), before that loss of vision moves more centrally and becomes noticeable. It is not usually until central vision loss occurs, when its sufferers realize something is not right. Sadly, by this point most of the damage has been done.

The best approach to avoid becoming a victim of open angle glaucoma is to have regular eye examinations. If you have a family history of glaucoma, high or low blood pressure or diabetes, it is highly recommended to undertake regular eye examinations.

Warning signs of closed angle glaucoma

Unlike open angle glaucoma, angle closure glaucoma commonly comes with a sudden attack and a series of symptoms due to the increase in pressure behind the eye. Some of the symptoms include:

  • Blurred vision
  • Severe pain behind the eye region
  • Sudden loss of sight
  • Pupils are different sizes
  • Vomiting and nausea
  • Strong headaches
  • Seeing halos of light

Angle closure glaucoma is a common cause of irreversible blindness. 

Risk groups of glaucoma

Age seems to be a huge risk factor, as open angle glaucoma is rare in Americans under the age of 50, yet it affects 8% of those over the age of 80. In particular, certain ethnicities are more at risk of developing glaucoma, including:

  • African Americans & Hispanics The most common form of glaucoma, open angle glaucoma, is five times more common in African Americans and Mexican Americans, than that in Caucasians. In African Americans, it is noted that glaucoma often develops at an earlier age than Caucasians, and is likely to progress a lot faster.
  • Asian ethnicities -From various studies, it has been found that Asia accounts for 77% of angle closure glaucoma.

Diagnosis of Glaucoma

There are many tests that can be carried out by your eye doctor to determine whether or not you have glaucoma. Regularly having your eyes checked over by a specialist is the best way to avoid glaucoma. Diagnosing glaucoma early on, allows treatment to begin to preserve your sight.

Because open angle closure glaucoma has little to no symptoms, many tests may be required to be undertaken, before reaching a final diagnosis.


This is a test that helps to determine the pressure inside your eye called intraocular pressure. Elevated pressure within the eye is known to cause damage to the optic nerve. Your eye doctor will place eye drops into your eye that works as an anesthetic.

The tonometer machine is placed in front of you, where you can comfortably rest your chin and forehead against the padded support. A slit lamp is moved into position to focus on the center of your eye.

The tonometer device on the lamp then presses slightly against your cornea. The reaction to this slight pressure is then measured by the tonometer sensor. This test is essential in diagnosing glaucoma. The eye pressure result recorded by what is called millimeters of mercury or mmHg.  

Visual Field Test (Perimetry test)

If you are found to have higher than average readings of mmHg in the tonometer pressure test, your doctor will next want to determine if any damage has occurred to the optic nerve, as a result of that elevated pressure.

This type of test measures how well you respond to certain objects or lights appearing on a screen in front of you. You will look inside a bowl-shaped instrument that is called a perimeter, with your forehead and chin resting on padded support.

The test is performed on one eye at a time, where you press a button as soon as you see a flashing object within the window. If you missed an object or flash, this will be recorded on the computer, determining if you have any peripheral loss of vision or otherwise. Any peripheral vision loss is linked to damage of the optic nerve. You can expect the visual field test to last around 10 to 20 minutes.

The visual field test is a type of test that can be used repeatedly in the future, in order to help monitor your glaucoma. This is especially important if your doctor believes you are in the early stages of this condition and is vital for preserving vision. Of course this test also helps to determine the level of treatment you will receive.


Gonioscopy is a type of test that specifically examines how fluid drains from your eye via tiny canals. Much like the tonometer test, a slit lamp is used along with the eye drops that act as an anesthetic. A contact lens is placed on the eye and a beam of light is used to determine the angle in which the lens sits.

If the test shows that the angle between your cornea and iris is not within normal measures, then your doctor can determine how this affects the drainage of fluid from your eye. Essentially, your doctor will be able to tell if the drainage angle is open or closed.


Pachymetry is important for measuring the thickness of your cornea. Generally, those with less thickness in the cornea, are found to be at greater risk of developing glaucoma.

Most advanced modern tests are carried out by way of hand-held ultrasound technology. Your doctor will place anesthetic eye drops into your eye, before carefully placing a pachymetry probe tool against the center of your cornea. An ultrasound wave will then measure the thickness of your cornea. This is considered to be a very quick and easy evaluation.

Treatment of Glaucoma

Depending on how far your glaucoma has progressed, most cases are able to be controlled by medication. However, with many advances in surgical procedures, you may wish to consider surgical options.

While there are particular treatments that can delay loss of vision, scientists have still not been able to find a cure for glaucoma. This means that any vision that has been lost along the way cannot be restored. Some common treatments include:


There are certain types of prescription medications that your eye doctor may prescribe to you, that help to reduce the amount of fluid that is produced within the eye. Some pills also help to better drain fluid from your eye. In turn, this helps to reduce the pressure inside the eye. Common medication used to treat glaucoma include:

  • Betagan
  • Osmitrol
  • Trusopt
  • Alphagan
  • Lumigan
  • Pilopine

As with any medication, you may experience unwanted side-effects, which should be reported to your doctor if it raises any concerns.

Eye drops

Unlike regular eye drops that help to hydrate dry eyes, glaucoma eye drops are specially medicated to help lower eye pressure. This is done by either reducing the amount of fluid your eyes produce or by helping that fluid to better flow from the eye, via the drainage canal.

Laser surgery for angle closure glaucoma

Iridotomy Angle closure glaucoma requires immediate medical attention and treatment. Often surgery is performed to help fluid drain freely from the eye. The main type of surgery carried out for angle closure glaucoma is called iridotomy, where your surgeon uses a laser to create small holes over the iris, in order to assist in the drainage process.

Iridotomy is a type of surgery that can also be used as a preventative treatment for those that show signs of the disease developing.

Laser surgery for open angle glaucoma

Trabeculoplasty– The surgeon will place special eye drops in your eye to numb the area before guiding a tiny laser beam to the canals where fluid drains from your eye.

The laser makes small incisions in the drainage holes, which helps fluid to drain freely from the eye. This is a good option for those that have a form of open angle glaucoma that gradually worsens over time or for those that don’t react well to any prescribed medication used to treat their glaucoma.

Other types of surgery

Viscocanalostomy– Much like laser surgery, this technique aims to increase the flow of fluid from the eye by removing a section of the white covering of the eye in patients with open angle glaucoma. This type of surgery is gaining a lot of interest as it has a very high success rate. It has also been recognized as a safe and effective treatment, for those with open angle glaucoma, in developing countries where other medical treatments are limited.

Trabecular stent bypassThis involves inserting a very small tube into your eye to help to increase fluid drainage. The micro-tube is around 1.00mm in length and 0.33mm in height, and claims the title for the smallest ever medical device. The success of the surgery is high, and also helps in reducing the future use of ongoing glaucoma medication.

Glaucoma is a disease that is becoming more common in our ageing society. While it does have daunting consequences in terms of robbing your vision, quite often without any symptoms, regular eye checks can boost your confidence in preserving your vision as you move into your older years. 

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