Glaucoma

Generally, glaucoma occurs when the pressure inside the eyeball becomes higher than it should be. This can happen suddenly or be more gradual. However, glaucoma can also occur with normal eye pressure. Concern about the diagnosis is usually identified by an optician and the diagnosis is confirmed and treated by an ophthalmologist.

Glaucoma is common in older adults, although it can occur at any age, including in infancy. Across the globe, it is the second leading cause of blindness after cataracts.

There are several different types of glaucoma depending on the underlying cause:

• chronic open-angle glaucoma or primary open-angle glaucoma
• primary closed-angle glaucoma
• normal-tension glaucoma
• congenital glaucoma

In most cases, glaucoma is caused by obstruction of the internal aqueous drainage system and subsequent damaging effects on the optic nerve.

However, the underlying cause of this blockage depends on the type of glaucoma you have:

• chronic open-angle glaucoma or primary open-angle glaucoma – this is the most common type of glaucoma. It develops slowly over several years and is partly due to the gradual blockage of tiny drainage channels that allow fluid to pass out of the eye to control eye pressure. Often, these blockages occur more frequently with age.
• primary angle closure glaucoma – this type of glaucoma develops due to the internal structures of the eye increasing the risk of elevated pressure. More rarely the closure can be ‘acute’ leading to a more rapid ‘attack’ of glaucoma.
• normal-tension glaucoma – this type of glaucoma is a subset of primary open-angle glaucoma and occurs despite pressure in the eye being normal. The treatment options are very similar to primary open-angle glaucoma but your ophthalmologist will also discuss some other risk factors that need to be considered with this diagnosis.
• secondary glaucoma – this diagnosis of glaucoma is typically found when there has been some other eye disease (such as chronic inflammation) that predisposes the eye to glaucoma.
• congenital glaucoma – a child may be born with glaucoma or develop it in their first few years of life. So, congenital glaucoma is glaucoma diagnosed in a newborn or a child. It is caused by an underlying medical condition or injury which blocks drainage in the eye, causing pressure to build which damages the optic nerve.

Other than ageing, the risk factors for glaucoma include:

• a family history of glaucoma
• being of African, Hispanic or Asian heritage
• high blood pressure
• previous eye injury or surgery
• diabetes
• farsightedness or nearsightedness
• long-term use of steroid medications
• migraine

Many people with glaucoma are not aware they have it, because, at first, there are no symptoms. Symptoms can come on very gradually, making them easy to miss.

When you do start to develop signs of the condition, they are likely to depend on the type of glaucoma you are experiencing. This means that your symptoms may be different to those affecting someone else who also has the condition.

The symptoms for each type of glaucoma include:

Chronic open-angle glaucoma (typically when moderate to advanced)

• gradually developing patchy blind spots in your peripheral vision
• reduced central vision

Primary angle closure glaucoma (acute onset)

• headaches
• pain in your eye
• nausea or vomiting
• blurred vision
• rainbow-coloured halos or rings around lights
• red eyes

Normal-tension glaucoma

• gradual blurred vision
• reduced peripheral vision

Congenital glaucoma (in an infant or young child)

• a dull or cloudy eye
• excessive blinking
• watery eyes or tears when not crying
• blurred vision
• progressive nearsightedness
• headaches