Can glaucoma cause blindness?

Glaucoma is a common eye condition that everyone should be aware of as they get older. Vision lost to glaucoma cannot be recovered, however, early diagnosis and monitoring can prevent further damage. Hence, booking your annual eye appointment with an optometrist is essential in diagnosing glaucoma early on. Mr John Brookes is a world-renowned ophthalmic surgeon and an expert in glaucoma. Find out what this eye disease is, how it could affect you and how it is treated.

What is glaucoma?

Glaucoma is a group of eye diseases that cause progressive damage to the optic nerve. The optic nerve is responsible for transmitting light signals from the eye to the brain. The main cause of this damage is increased eye pressure (intraocular pressure), however, not all cases of glaucoma are caused by increased eye pressure. To begin with, glaucoma may not produce any symptoms, but if it is not diagnosed and treated, there can be a loss of the peripheral visual field initially and then blindness.

What causes pressure within the eye?

A layer of cells in the eye called the ciliary body produce fluid called aqueous humour which is needed for normal eye function. This fluid is drained from the eye through a structure called the trabecular meshwork. If this flow of fluid through the trabecular meshwork is obstructed, the pressure inside the eye can increase, allowing glaucoma to develop. Normal pressure in the eye should be between 12 and 21 mmHg.

Types of glaucoma

There are several types of glaucoma, but closed angle and open angle glaucoma are the two main types that are diagnosed.

• Open angle glaucoma:

This is the most common type of glaucoma, affecting more than 2% of adults aged 40 and over. This type of glaucoma becomes more common with age, as well as myopia (short-sightedness) and sometimes diabetes. Additionally, open angle glaucoma is more severe in people of African or Caribbean origin.

Whilst the exact cause of glaucoma is not yet known, it does run in families, which is why it is so important to be tested annually by an optometrist if you know it runs in your family. The nature of open angle glaucoma is that it is a slow, progressive disease that can go unnoticed until it is too late, causing loss of peripheral vision and eventual blindness. Open angle glaucoma generally affects both eyes and is completely painless in its progression.

• Closed angle glaucoma:

This form of glaucoma is less common in the UK, but it is more common in older patients, as well as those of an East Asian origin and people with hypermetropia (long-sightedness).

Closed angle glaucoma presents very suddenly, causing the eye to become sore and red. This sudden onset occurs because the trabecular meshwork becomes blocked, causing the eye pressure to raise rapidly. Onset can be preceded by intermittent symptoms, including seeing rainbows or haloes around lights. Closed angle glaucoma must be treated as an ocular emergency and is often treated with laser treatment. If you are identified as being at risk from this type of glaucoma, it can be treated with preventative measures.

How is glaucoma treated?

Most glaucoma patients are treated medically with special eye drops which aim to reduce the intraocular pressure and to prevent further damage to the optic nerve. Even though glaucoma cannot be cured, treatment can be successful in controlling the disease. If medication fails to reduce the eye pressure, then sometimes laser treatment will be carried out, however, this is usually performed as a temporary measure. For patients who do not respond enough to medication, glaucoma surgery can be performed.

Glaucoma surgery:

A trabeculectomy is the most common surgical procedure used to treat glaucoma. This operation aims to create a passage for the fluid to drain from the eye into a space below the conjunctiva (this is known as the bleb). This is a widely successful operation, but there are sometimes complications. For example, sometimes there will be excessive drainage from the eye, resulting in eye pressure that is too low, or infection may set in which can be sight-threatening. Another risk is excessive scarring below the conjunctiva which can cause the operation to fail, however, nowadays we use special drugs to prevent scarring.

For very advanced cases of glaucoma, a glaucoma tube can be inserted into the eye to drain excess fluid. However, this is considered a major operation with some risk of complications, although it can provide a useful way of reducing eye pressure and preventing blindness.

If you are concerned about your visual health, make an appointment with an expert.