Glaucoma is a group of eye diseases which cause irreversible vision loss due to optic nerve damage. Loss of sight is normally gradual, and may be first noticed with a loss to your peripheral vision.
2% of Australians will develop the disease in their lifetime, and you are ten times more likely to develop it if it runs in your family. Glaucoma is the second leading cause of blindness, after cataracts.
What causes glaucoma?
Your optic nerve is made up of roughly a million nerve fibres which connect the back of the eye to the brain. A rise in intraocular pressure (IOP) can be caused by a build-up of fluid within the eye, which may damage the optic nerve.
This fluid (aqueous humour) keeps they eye healthy and normally drains. However, when it is overproduced or prevented from draining normally, it may increase the pressure in the eye.
As the nerve deteriorates, blind spots will start to develop in your field of vision.
Types of glaucoma
Multiple types of glaucoma exist, each characterised by differences in their presentation.
Open-angle glaucoma is the most common form of the disease. Despite having a normal drainage angle, the trabecular meshwork (a type of specialised tissue which helps drain the eye) becomes partially blocked, causing pressure on the optic nerve.
Symptoms of open-angle glaucoma include:
- Patchy blind spots in your peripheral or central vision
- Tunnel vision (in advanced glaucoma).
Closed angle glaucoma occurs when the iris bulges forward and blocks the drainage angle between the cornea and the iris, stopping fluid from circulating through the eye. When this closure happens suddenly, it is called acute angle-closure. If it is gradual, it is called chronic angle-closure.
Symptoms of angle-closure glaucoma include:
- Severe headaches
- Eye pain
- Nausea and vomiting
- Blurred vision
- Halos around lights
- Redness of the eyes
Acute angle-closure glaucoma is an eye emergency. If these symptoms onset suddenly, it is important to visit your local emergency department immediately. Immediate treatment is necessary to prevent permanent vision loss.
Normal tension glaucoma
As the name suggests, normal tension glaucoma develops despite normal pressure in the eye. Medical professionals are not 100% sure why this happens, but could be due to having a sensitive optic nerve or poor blood flow in the arteries.
Glaucoma in children
Some children may be born with glaucoma, or may develop it early on in their lives. This is normally due to an underlying medical condition or drainage blockages.
Symptoms in children include:
- Unusually large eyes
- Cloudiness of the cornea
- Excessive tearing
- Sensitivity to light
Pigment granules from the iris can build up in the drainage channels, causing blockages and increasing the eye’s pressure intermittently.
Symptoms of pigmentary glaucoma include:
Initially, there may not be any symptoms at all. However, this can change as the condition progresses. This may result in:
- Loss of peripheral vision
- Halos and blurry vision
- More pigment in the drainage channels
- A thinning of the iris
- Optic nerve damage
What are the risk factors?
More than half the people living with glaucoma are still unaware that they have the disease, so it is important to be aware of the warning signs.
Factors which may put you at a higher risk of developing glaucoma include:
- High internal eye pressure
- Being over 60 years of age
- People of colour are at higher risk
- A family history
- Underlying medical conditions such as diabetes, heart disease, high blood pressure and sickle cell anaemia
- Thin corneas
- Being extremely nearsighted or farsighted
- Previous eye surgery
- Using eye medication regularly, including eye drops.
How is glaucoma prevented?
There are currently no known ways of prevention. However, the disease can be managed if detected early, and significant vision loss can be prevented.
To increase your chances of detecting glaucoma and addressing it before it causes significant vision detraction, it is important to:
- Know your family’s health history, as the condition tends to run in families.
- Have regular eye examinations, particularly if you are considered at-risk.
- Exercise safely, as exercises like jogging may increase the risk of pigmentary glaucoma.
- Wear eye protection, as eye injuries can lead to the disease. This is particularly important when using power tools.
In some cases, medication can be used to control and lower the pressure on the eye. In more advanced cases, surgery or laser treatment may be required to treat your glaucoma.
Dr Joseph Park conducts laser surgical procedures at Westside Eye Clinic.
Selective Laser Trabeculoplasty (SLT) involves directing laser pulses at the eye’s drainage flow channels. This stimulates the cells and clears away any debris causing blockages. This will lower the pressure on the eye, and can be used in conjunction with specialised eye drops.
YAG laser peripheral iridotomy is used for angle-closure glaucoma. It creates a channel in the iris, opening up the drainage angle and preventing the disease from progressing any further.
If medication or laser surgery fail to halt the progress of your condition, then Dr Park might recommend surgery as the next step in your treatment.
There are a few surgical procedures available to treat the disease.
Minimally Invasive Glaucoma Surgery (MIGS) – In mild to moderate cases, microstents are placed in the drainage angle to bypass the blocked trabecular meshwork. This restores the natural drainage system.
Filtration Surgery (Trabeculectomy) – People who don’t respond to other treatments will undergo filtration surgery. A new pathway will be created to allow the fluid of the eye to bypass the obstruction, and drain out of the eye.
Ahmed Drainage Implant – The Ahmed Drainage Implant is a drainage device that is inserted into the eye to control pressure.