Untreated, glaucoma can cause blindness (CERA 2020).

Despite this, among the estimated 300,000 Australians living with glaucoma, only half are aware that they have the disease (CERA 2020).

This may be because the onset of glaucoma can be a gradual one. So much so, that a significant amount of side vision will be lost before the individual has even noticed they have a condition (Glaucoma Australia 2017).

What is Glaucoma?

Glaucoma is the name given to a range of conditions that lead to optic nerve damage. This is the nerve that transmits signals from the eye to the brain to create the image we see (Vision Eye Institute 2022).

If a considerable number of nerve fibres are affected, the peripheral field of vision is lost - this loss slowly creeps toward the central vision. Currently, glaucoma cannot be reversed (Vision Eye Institute 2022).

Types of Glaucoma

Glaucomas can typically be separated into two subgroups:

1. Open-angle glaucoma (where the drain of the eye is fully open)
2. Closed-angle glaucoma (where the drain of the eye is partially or fully blocked).

(Glaucoma Australia 2020)

Furthermore, glaucomas can be either primary (unknown cause) or secondary (caused by another condition) in nature (Glaucoma Australia 2020).

Common types of primary glaucoma include:

Primary Open-Angle Glaucoma

In the case of primary open-angle glaucoma (POAG), a patient loses their peripheral vision due to the optic nerve becoming damaged. Insufficient drainage of fluid from the eye is responsible for pressure and nerve damage (Glaucoma Australia 2020).

This type of glaucoma typically does not cause pain and is therefore difficult to detect. As with other types of glaucoma, the early signs may be very subtle (Glaucoma Australia 2020).

POAG is the most common type of glaucoma - it is responsible for around 90% of reported glaucoma cases in Australia (Glaucoma Australia 2017).

Normal Tension Glaucoma

Normal tension glaucoma is the term given to cases in which the patient has ‘normal’ eye pressure and therefore other reasons must be considered in determining changes in nerve pressure and visual field loss (Glaucoma Australia 2020).

Normal tension glaucoma accounts for roughly one-third of glaucoma cases in Australia (Glaucoma Australia 2020).

Primary Angle-Closure (PAC) and Primary Angle-Closure Glaucoma (PACG)

A primary angle-closure (PAC) is a result of an inherited narrowness of the drainage angle of the eye. Aqueous fluid must drain through the angle between the trabecular meshwork and the iris and in this condition, it is unable to (Glaucoma Australia 2020).

The term primary angle-closure glaucoma (PACG) refers to optic nerve damage caused by a PAC (Glaucoma Australia 2020).

PAC and PACG are more common in people who are long-sighted, older adults, females and/or of Asian background (Glaucoma Australia 2020).

Acute Angle-Closure Glaucoma

People with PAC and/or PACG may be prone to experiencing an acute angle-closure glaucoma attack. This is a medical emergency requiring urgent intervention (Glaucoma Australia 2020).

Symptoms of an acute attack may include blurry vision, coloured rings around lights, severe eye pain, redness, nausea and vomiting (Glaucoma Australia 2020).

Childhood Glaucoma

An abnormal drainage system is responsible for childhood glaucoma. It can be detected by noticing that children are particularly sensitive to light and have excessively cloudy and watery eyes (Glaucoma Australia 2020).

Childhood glaucoma is rare and devastating when it does occur. Cases tend to vary in severity. (Glaucoma Australia 2020).

Symptoms of Glaucoma

Symptoms most often associated with glaucoma include:

• Painless but blurred vision
• Loss of peripheral vision
• Trouble adjusting to low light.

(Vision Australia 2018)

Risk Factors for Glaucoma

Those with a family history of glaucoma are at the greatest risk of developing this condition. In fact, having a first-degree relative with glaucoma increases the risk of developing glaucoma ten-fold (CERA 2020).

Other main predictors include:

• Age (over 40-50)
• High intraocular (eye) pressure
• Myopia (short-sightedness) or hyperopia (long-sightedness)
• Diabetes mellitus
• Migraines
• History of eye surgery or injury
• Prolonged use of steroid medicines
• Hyper or hypotension.

(Vision Australia 2018; Healthdirect 2019)

Those in high-risk categories should have their eyes examined well before the age of 35 (Vision Australia 2018).

Diagnosing Glaucoma

If a doctor or optometrist suspects that a person may have glaucoma, they may be referred to an ophthalmologist for further investigation and analysis. A range of eye tests will then be taken in order to confirm the diagnosis (Vision Eye Institute 2019).

Treating Glaucoma

While damaged nerve cells caused by glaucoma are irreversible, there is treatment available to prevent or delay further damage, primarily by reducing the pressure in the eye.

Typically, this involves:

• Eye drops or medicine
• Laser surgery or other surgery to open or create a new drainage channel.

(Healthdirect 2019)

Preventing Glaucoma

The most effective way to ensure glaucoma prevention is to have regular eye tests - early diagnosis and treatment are essential (CERA 2020).

Further Information

To gain a better understanding of glaucoma, Glaucoma Australia has curated a list of several stories from the perspectives of people living with the condition: https://www.glaucoma.org.au/about-glaucoma/glaucoma-stories/

References