Glaucoma is commonly known as the ‘sneak thief of sight’ because it can cause irreversible vision loss without any obvious symptoms. Up to 50% of all people with glaucoma in Australia are not even aware they have the condition. However, if it is diagnosed early enough, treatment can begin and serious vision loss can be prevented.
The term glaucoma actually refers to a group of conditions that lead to eye (optic) nerve damage. This nerve transmits signals from the eye to the brain to produce the image that we see. When a significant number of nerve fibres are damaged, blind spots begin to appear in our side (peripheral) field of vision and then central vision, until eventually all sight is lost. Vision loss caused by glaucoma is permanent.
Most cases of glaucoma are due to an increased pressure inside the eye (intraocular pressure), either from the drainage angle being closed (angle-closure glaucoma) or the drainage angle being open but damaged (open-angle glaucoma).
A specific part of the eye called the trabecular meshwork provides natural resistance to the drainage of fluid from the eye. It is a failure of this meshwork that often causes raised eye pressure and, in turn, glaucoma nerve damage.
Glaucoma nerve damage can also occur with normal eye pressure. This is known as normal-tension glaucoma and is thought to be related to poor blood supply to the eye nerve.
Anyone can get glaucoma, but some people may be at higher risk than others.
Risk factors include:
Most cases of glaucoma are asymptomatic – there is no pain and vision seems quite normal. However, without treatment, you will gradually lose your side (peripheral) vision without noticing. This vision loss will slowly creep towards your central vision until, in the most serious cases, no vision remains. Other symptoms include blurred vision and difficulty adjusting to low-light conditions.
In angle-closure glaucoma, there is a risk that you might experience sudden onset of eye pain, vision loss, headache, nausea or vomiting. This is due to the drainage angle suddenly and completely closing up, causing the pressure inside the eye to rise very quickly. This is a medical emergency and you should contact your ophthalmologist immediately or visit the nearest emergency department.
If your GP or optometrist suspects that you have glaucoma, you will be referred to an ophthalmologist for further investigation. A number of tests will be carried out to confirm the diagnosis, including:
Unfortunately, there is no cure for glaucoma. But there are a number of treatment options available to help reduce eye pressure and minimise or prevent further vision loss. Sometimes a combination of treatments may be used.
Starting treatment as early as possible is critical for preserving as much of your remaining eyesight as possible, but vision that has already been lost cannot be recovered. Make sure you have regular eye checks with an optometrist, even if you don’t require glasses to see, as they will routinely check your eye pressure. This is particularly important for people who are at high risk of developing glaucoma.
Patients with glaucoma require ongoing care by an ophthalmologist.
Long-term use of eye drops is very effective in controlling eye pressure for most people with glaucoma. However, these medications can sometimes stop being effective or may cause side-effects, such as stinging or irritation.
It’s important that you don’t stop treatment without consulting your ophthalmologist first, as this may lead to further loss of vision. This is the case even if your eyes feel comfortable and you think your eye pressure is ok. Eye pressure can only be measured using a special tool called a tonometer.
Sometimes it’s hard to remember to take your eye drops. Having a routine (e.g. when you first wake up or when you brush your teeth) can be useful, or you might like to try setting an alarm on your mobile phone.
Laser treatment for glaucoma is different to the laser eye surgery used to help people get rid of their glasses or contact lenses.
Laser treatment for glaucoma is performed in the clinic and does not require admission to a day surgery. Anaesthetic eye drops are used to numb the eye so there is little or no discomfort.
If your condition continues to progress despite medication and laser, your ophthalmologist may recommend a third treatment – surgery.
There are many forms of glaucoma surgery and your ophthalmologist will discuss the option most suitable for you.
The iStent, iStent inject and Hydrus Microstent are a part of a group of glaucoma operations known as minimally invasive glaucoma surgery or MIGS. They have an excellent safety profile, but do not have the same pressure-reducing ability as conventional trabeculectomy surgery.
MIGS procedures are usually combined with cataract surgery and are suitable for mild-to-moderate glaucoma. The stents are placed in the drainage angle to bypass the blocked trabecular meshwork and restore the natural drainage system for fluid in the eye. This, in turn, reduces pressure on the optic nerve.
Vision Eye Institute specialists are currently conducting a quality-of-life study assessing the ways in which the iStent and iStent inject benefit patients with glaucoma.
This is the standard surgery for glaucoma, having been used for many decades. Trabeculectomy surgery is generally reserved for people who no longer respond to other treatments or who are in the advanced stages of the disease. During surgery, a new pathway is created to allow fluid to bypass the obstruction and drain out of the eye.
This procedure is usually performed under a local anaesthetic in one of our day surgeries.
In rare, advanced cases where a trabeculectomy is not suitable or becomes ineffective, a glaucoma drainage device can be inserted to control the eye pressure. The implant, also known as the Baerveldt tube, has a plate that sits on the surface of the eye and a small tube passes into the eye to divert fluid out.