Glaucoma can cause loss of vision, however, treatment can save sight. These key facts about glaucoma indicate the importance of screening and early detection, as well as adherence to treatment schedules.
Of the around 300,000 Australians that live with glaucoma, up to 50% are unaware that they have the disease 1.
Definition of Glaucoma
Glaucoma is the name of a group of related diseases where the pressure within the eye is typically increased, usually due to malfunction of the drainage channels within the eye. This pressure can cause damage to the optic nerve that links the eye to the brain. The extent of damage to the optic nerve can range from mild to severe, with extreme cases causing total blindness. Unfortunately, symptoms often go unnoticed until damage to the eye has already occurred.
There is no cure for glaucoma but once diagnosed it is usually possible to slow or stop the progress of the disease. Early diagnosis is therefore essential and this is why regular eye examinations are recommended, preferably every 2 years for anyone over 40 years of age. The test and assessment process involves checking of the optic nerve, eye pressure and peripheral vision.
Symptoms of Glaucoma
There are usually no symptoms in the early stages of the disease. As it progresses, vision seems to fluctuate and peripheral vision fails. Because glaucoma is often painless, patients sometimes fail to continue using the recommended medications and this has become a major cause of blindness or extensive vision loss in glaucoma patients.
Causes of Glaucoma
This condition usually occurs when fluid in the eye builds up, causing higher pressure than the eye can withstand. Other causes may include trauma, genetic disorder and low blood flow to the optic nerve.
Although anyone can develop glaucoma, some people have a higher risk. They include those with a family history of glaucoma, diabetes, migraine, short or long sightedness, a history of eye injury and high or low blood pressure.
Other factors, too, can compromise the blood flow to the optic nerve, causing nerve cells to die, resulting in the loss of peripheral vision as the optic nerve struggles to recover. This means that even people with normal or low eye pressure can be susceptible to the disease. These additional risk factors include atrial fibrillation,
reduced blood pressure at night and Obstructive Sleep Apnoea (OSA). 2
There are four main types of glaucoma:
All four types are dangerous and require immediate treatment.
1. Primary Open Angle
The most common type, primary open-angle glaucoma causes a gradual loss of vision, due to the eye’s filter mechanism becoming more resistant to the outflow of fluids. It can, however, also occur without a pressure build-up, making it more difficult to diagnose.
Primary open-angle glaucoma is usually age-related and is most common in developed countries, with an incidence of around 2% of people over 40, increasing to 10% of people over 70. People of African descent are in greater danger than those of Caucasian descent.
2. Primary Closed Angle
Primary closed-angle glaucoma can occur at any age when there is a sudden blockage of fluid into or out of the eye. It is usually accompanied by irritation, sudden vision deterioration or nausea and often, in the early stages, by coloured lights and hazy vision. It can be very painful or can occur in a series of mild attacks. If any of these symptoms occur you should see your doctor or optometrist immediately.
Secondary glaucoma develops when other medical conditions block the supply of fluid within the eye. The range of causes includes surgery, advanced cataracts, eye injuries or severe inflammation. It can arise as a complication of diabetes.
This type is more common in boys than girls and occurs when a birth abnormality blocks the drainage channels within the eye. Diagnosis can be difficult, as the child can’t tell you there is a problem, but it is nevertheless usually detected within the first three months of life. If you notice that your child’s eye is cloudy or enlarged you should contact your doctor immediately.
Glaucoma Treatment and Testing
There are several tests used by optometrists to check for this disease. These include viewing the optic nerve using special instrumentation, pressure testing (known as tonometry) and a field test, where spots of light are shown on a screen to test the extent of vision.
Insight Optometrists have the latest technology for viewing the interior of the eye and the optic nerve. Eye examinations include the use of OCT (Ocular Coherence Tomography) to measure the retinal nerve fibre layer and ganglion cell count.
No single test is definitive enough to rule out glaucoma, but the combination of these regular eye tests and examinations will ensure that the first signs of the disease are detected as early as possible.
There is unfortunately no cure for this condition. It can be controlled, though, and further loss of sight can be prevented or slowed.
Treatment usually starts with eye drops to lower the pressure within the eye, but in more severe cases it may involve laser treatment or surgery. The insertion of shunts or stents during eye surgery, including a device called iStent, can help to lower the pressure in the eye and reduce dependence on glaucoma medication.
Whilst there is no known way to prevent glaucoma, recent research has shown that regular exercise, a healthy diet and abstinence from smoking can substantially reduce the risk of developing it, as well as many other diseases.
Because of the high incidence of glaucoma and the fact there may be no apparent symptoms before substantial damage is done to the optic nerve, early detection and treatment remains the best way to prevent severe vision loss or blindness.
Glaucoma is a progressive disease and an optometrist can detect the start of symptoms, or the potential to develop the condition, through testing and evaluation during an eye exam.
Insight Optometrists recommends a check-up every two years for everyone over 40 and more frequent examination if there is a family history of the disease, previous eye injury or vision problems, or for people prone to migraines, those have diabetes, or those who have high or low blood pressure.
Early detection can mean that irreversible damage to the eye may be largely prevented with effective treatment, meaning that regular eye checks may potentially save sight.
Make it a priority to book an appointment today with Insight Optometrists, Indooroopilly, for a full eye examination which includes a glaucoma test.
1. Glaucoma Australia
2. Glaucoma and obstructive sleep apnoea syndrome.
Faridi, 0., Park, S. C., Liebmann, J. M. and Ritch, R. (2012)
Clinical & Experimental Ophthalmology, 40: 408-419.