Glaucoma is a type of optic neuropathy, a group of diseases that affect the optic nerve of the eye. The optic nerve is the direct connection between the eyeball and brain and is responsible for carrying the neural signals from the eye’s light-sensing structures to the visual processing centres of the brain. In Australia, approximately 2 out of every 100 people will develop glaucoma in their lifetime. To learn more about what is glaucoma and how is it treated, keep reading.
Signs of Glaucoma
Glaucoma causes permanent and irreversible vision loss. It is typically associated with elevated pressure inside the eyeball, known as intraocular pressure. This high intraocular pressure can cause damage to the optic nerve. A healthy intraocular pressure is usually considered to be within the range of 10-21mmHg (millimetres of mercury), however, this is only a guideline. There are cases of glaucoma that can develop and continue to progress despite a person’s intraocular pressure being within this range. Conversely, someone may have an intraocular pressure above 21mmHg and still have a healthy, robust optic nerve.
Because the optic nerve has no pain receptors, you can’t feel any pain or discomfort even if the majority of the nerve fibres are damaged. For this reason, glaucoma is nicknamed the “sneak thief of sight”, because the signs of glaucoma often go unnoticed and the disease may remain undiagnosed until its more advanced stages.
The vision loss from glaucoma typically begins in the sides of your vision, also known as your peripheral field of view. We are usually less aware of changes to these areas of our sight because most of our attention is focused on our central vision. As the disease progresses and if you haven’t been able to access timely glaucoma treatment, eventually your field of view becomes more and more narrowed, eventually constricting down to tunnel vision. Although we rely on our central vision for crucial tasks such as reading, writing, and colour discrimination, our peripheral sight is still important. Loss of this area of your vision will affect tasks such as:
- Walking around without bumping into objects
- Driving safely
- Participating in sports
- Noticing approaching dangers
The signs of glaucoma may be more obvious with one specific type of the disease, known as angle-closure glaucoma. During an angle-closure attack, the intraocular pressure can spike very high.
If you experience an angle-closure attack, it can be difficult to realise what’s happening. Symptoms can include:
- A red, aching eye
- Seeing haloes around lights
- Cloudy vision
- Vomiting and nausea
If you think you may be experiencing acute angle-closure glaucoma, it’s imperative to seek medical attention immediately in order to preserve your vision as the damage to your optic nerves can be severe. Visit your local optometrist, ophthalmologist, or hospital emergency department without delay.
Diagnosis and Treatment of Glaucoma
Because glaucoma is known to be largely asymptomatic in the majority of cases, it’s important to keep up with routine eye checks with your optometrist or ophthalmologist. Through various tests, regular examinations are able to catch glaucoma early before you even realise something is wrong. If you are diagnosed with glaucoma, the sooner you can commence glaucoma treatment, the better the prognosis for your sight.
In order to diagnose glaucoma, your eye care practitioner will perform tests such as:
- Intraocular pressure measurement, also known as tonometry
- Examination of your optic nerve and retina
- Assessment of other structures of your eyeball that may indicate you’re at risk of glaucoma
- Imaging tests such as retinal photography or optical coherence tomography to record the health of your nerve fibres
- Visual field testing, to map the sensitivity of your peripheral vision
It is not uncommon for a person to be considered at risk of glaucoma or a “glaucoma suspect”. This may include people who have high intraocular pressures or abnormally thin nerve fibres, yet do not demonstrate any defects in their visual field. There are a few valid ways of managing someone who is a glaucoma suspect, based on your eye care professional’s findings, your risk factors, and your personal preferences. If you are at high risk or have a high likelihood of glaucoma, your optometrist or ophthalmologist may choose to commence glaucoma treatment as a preventative measure. Alternatively, you may opt to be monitored closely for signs of deterioration to your visual fields or optic nerve.
If your eye care practitioner believes it’s best to commence you on treatment, there are several options. Management of glaucoma can include:
- Intraocular pressure-lowering eye drops. These are instilled at least once per day and will need to be administered for the long term. Some people need multiple medications to control their pressures.
- Laser therapy. Selective laser trabeculoplasty is used to stimulate the drainage of fluid from the eye in order to lower the intraocular pressures. This may be performed once only or may need to be repeated.
- Surgery. There are various surgical options, all with the aim of increasing fluid drainage from the eyeball.
In some cases, you may be strongly recommended one particular treatment over the other. In other cases, you may have a choice. Ask your clinician to discuss the pros and cons with you.
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Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.