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Wollongong, Shellharbour, Kiama & Nowra Eye Surgeon

What is Glaucoma?

Fig. Normal optic nerve (Left) compared to a glaucomatous optic nerve (Right).

Fig. Normal optic nerve (Left) compared to a glaucomatous optic nerve (Right).

Glaucoma encompasses a group of eye conditions which cause damage to the optic nerve, the structure that carries nerve fibres from the eye to the brain. This results in irreversible vision loss starting in the periphery then slowly involving your central vision. being lost irreversibly. The main risk factor for the development and progression of glaucoma is elevated pressure within the eye.

What causes pressure within the eye?

Eye pressure is controlled by aqueous humour, fluid which fills the front part of the eye and drains through tiny channels, called the trabecular meshwork.

In a normal eye, there is a balance between the production and drainage of this fluid, but in glaucoma this balance is disturbed, which typically causes the eye pressure to rise. This is usually because the drainage of fluid from the eye becomes restricted.

Normal eye pressures ranges from 10-21 mm Hg. However, there is no specific level of elevated eye pressure that definitely leads to glaucoma; conversely, there is no lower level of pressure that will absolutely eliminate a person’s risk of developing glaucoma. Every optic nerve is unique and has a different eye pressure that it can tolerate. That is why early diagnosis and individualised treatment of glaucoma is the key to preventing vision loss.

What are the different types of glaucoma?

The two most common types of glaucoma are primary open angle and primary angle closure glaucoma.

Primary open angle glaucoma

Primary open angle glaucoma is the most common form, affecting approximately three percent of Australians. It is often referred to as “the silent thief of sight” as there are no symptoms until vision is severely and irreversibly damaged. It is estimated that 50% of Australians with this form of glaucoma are unaware that they have it.

Primary angle closure Glaucoma

Primary angle closure refers to an anatomical blockage of fluid drainage from the eye. It is more common with age, particularly in ‘long-sighted’ eyes. The most sinister form is acute angle closure, which occurs when there is no drainage of fluid from the eye causing the eye pressure to rapidly rise acutely. Symptoms include pain, seeing halos, cloudy vision and vomiting. It must be treated promptly or can lead to irretrievable vision loss.

How is Glaucoma Diagnosed?

glaucoma vision simulation wollongong eye doctor Steven Yun.jpg

Glaucoma is usually painless and vision loss unnoticed until it is advanced. It is therefore crucial to have regular eye health checks with your optometrist, who can pick up glaucoma at an early stage. The three main tests to check for glaucoma are:

  1. Viewing the optic nerve.

  2. Measuring pressure in the eye.

  3. Testing your field of vision. This may not be required if your optic nerve appears health and your eye pressure is within normal range.

Optometrists are trained to detect glaucoma, and if they are concerned, they will refer you to an ophthalmologist to confirm the diagnosis and discuss treatment options.

What investigations are needed to diagnose and monitor glaucoma?

Glaucoma can be difficult to detect, particularly early in the disease. At Illawarra Ophthalmology, Dr Yun has access to the most up-to-date equipment to diagnose and monitor your glaucoma.

  1. Visual Field Test

This test involves sitting in front of a concave dome and fixating on a target in the centre with one eye. Lights of different intensities are shone in your peripheral vision and you will be asked to click a button each time you see a light. Based on your responses, the computer analysis will generate a map of peripheral vision for each eye. This test is not only helpful in diagnosing glaucoma, but is particularly useful in monitoring for subtle changes in glaucoma over time.

Visual field test showing the progression of glaucoma over time

Visual field test showing the progression of glaucoma over time

2. OCT Scan of the Optic Nerve

The Optical Coherence Tomography (OCT) scan generates cross-sectional images of the optic nerve. Glaucoma changes the appearance of the nerve and the OCT can detect early, subtle changes to assist in diagnosing glaucoma. Serial OCT measurements can be used to monitor for glaucoma progression over time.

Figure. An OCT print out showing advanced glaucoma in both optic nerves.

Figure. An OCT print out showing advanced glaucoma in both optic nerves.

3. Corneal Thickness Measurement (Pachymetry)

The cornea is the dome shaped window at the front of your eye. Eye pressure is measured by pressing down on the cornea and evaluating the degree of depression. This can be influenced by corneal thickness as well as the eye pressure. Knowing the corneal thickness allows a more accurate measurement of the eye pressure. Furthermore, a reduced corneal thickness is associated with increased glaucoma risk, independent of the eye pressure.

Someone in my family has glaucoma. Does that mean I am at risk?

There is at least a four times increased risk of developing glaucoma if you have a close blood relative with the condition. If you have a family member with glaucoma, we advise you regularly see an optometrist to screen for glaucoma.

How is glaucoma treated?

Optic nerve damage from glaucoma is irreversible. The aim of treatment is to slow the progression of this damage to a rate that allows vision to be preserved. This is achieved by eye drops, laser or surgery. Dr Yun is an expert in glaucoma treatment and will provide you with a personalised plan which best suits you.