Definition
Glaucoma is the leading cause of blindness worldwide. It occurs when the pressure within the eye (IOP) is high for prolonged periods. This results in painless and progressive damage to the optic disc/nerve, resulting in vision loss. There are four main types of glaucoma:

1. Open-angle glaucoma
This is the most common form of glaucoma. It:

  • is caused by the slow clogging of the drainage canals, resulting in increased eye pressure;
  • has a wide and open angle between the iris and cornea;
  • develops slowly and is a lifelong condition;
  • has symptoms and damage that are not noticeable.

“Open-angle” means that the angle where the iris meets the cornea is as wide and open as it should be. Open-angle glaucoma is also called primary or chronic glaucoma.

2. Normal-tension glaucoma
This is where the pressure inside the eye is within the normal range but nerve damage still occurs.

3. Angle-closure glaucoma
This type of glaucoma is caused by a blockage in the drainage system. It is the only type of glaucoma that can be painful and develops rapidly. Patients may notice a severe ache in the eye along with eye redness and blurry vision. It can damage vision within a day or two, so an urgent assessment is needed.

4. Secondary glaucoma
This can arise due to other eye problems, such as inflammation, blood vessel blockage, trauma, and systemic body illness. Causes

  • Pressure in the eye (intraocular pressure - IOP). The principal cause of glaucoma is high pressure in the eye. This pressure comes from a build-up of a naturally produced watery fluid in the front part of the eye that provides nutrition to the tissues inside the eye. Pressure increases when there is an imbalance between the production and drainage of this fluid.
  • Structure and blood supply of the optic disc. In some patients, the eye pressure is within the normal range, but they still develop damage to the nerve (normal tension glaucoma).
  • Family history of glaucoma. Having an immediate relative with the disease significantly increases the risk. Anyone with a family history should have regular checks from the age of 35 and above.
  • Age. The incidence of glaucoma increases with age.
  • Other associated conditions. Other conditions may increase the risk of glaucoma, such as high blood pressure, diabetes, and short-sightedness.

Symptoms
There are usually no symptoms, until it is too late. Early detection, through regular and complete eye exams, is the key to preventing glaucoma-related blindness.

Treatment
1. Tonometry.

This determines the inner pressure of the eye. There are a number of eye machines that do this. Some have to contact the eye surfaces and others do not have to.

2. Gonioscopy.
This is a painless eye test in which a contact lens that enables the doctor to inspect the drainage angle of the eye is placed on the eye surface after numbing it.

3. Pachymetry.
This is a simple, quick, and painless test to measure the thickness of the cornea. It is important to assess this, as it can have a bearing on the accuracy of eye pressure measurements.

If glaucoma is detected, then the treatment can begin. The aim of treatment is to reduce the pressure (IOP) inside the eye, which will reduce stress on the optic nerve and slow down or stop any further nerve damage. It entails:
1. Medical treatment.
Eye drops are usually the first line of treatment for glaucoma. There are various types of eye drops that can be used.

2. Laser for narrow or closed-angle glaucoma.
Another form of laser surgery called YAG Peripheral Iridotomy (PI) surgery creates an opening through the iris, which allows the eye fluid to bypass the normal drainage pathway. This can reverse closed-angle glaucoma and prevent its development in those who have narrow drainage systems and are at risk of acute loss of vision.

3. Surgery.
Surgery can be used to control pressure inside the eye but is generally used only when eye drops have proven unsatisfactory. The surgery for high pressure control is called trabeculectomy. In this procedure, an alternative drainage pathway is created.

To Note
Once glaucoma is diagnosed, ongoing management and treatment is required throughout life. Fluctuations in eye pressure are damaging. Therefore, it is very important to ensure that eye drops are taken regularly as missed doses can be harmful. Remember:

  • Elevated pressures are painless;
  • Prevention of damage is the only way to avoid vision loss;
  • Once damage has occurred, it is permanent and irreversible.

Benefits of Treatment

  • Early treatment may decrease your chance of eye damage and loss of vision.
  • Eye pressure medicines help decrease eye pressure. They may also decrease the amount of fluid your eyes make or help your eyes drain better. These medicines may be eye drops or pills.
  • Trabeculectomy is a surgical procedure that creates a new channel for fluid outflow in cases in which the intraocular pressure is high and the optic nerve damage progresses. Long-term results vary, but generally, the success rate is good.
    Surgical implants that push fluid out of the eye may also be used to decrease pressure in the eye.

Frequently Asked Question about Glaucoma
Do I have to get up in the night to take my glaucoma eye drops? No. Having an undisturbed night is more important. If you have to take drops more than twice a day, put the drops in when you get up and when you go to bed and then space the other drops in between, during the day. Always wait for 5–10 minutes if putting more than one drop.