What is glaucoma?
Glaucoma is the name given to a few different types of eye conditions that cause damage to the optic nerve head, causing vision loss. Light enters the eye through your pupil and an image is cast on the retina, which is at the back of the eye. This image is then sent to your brain through nerve fibres that extend from the retina. These fibres all band together and form the optic nerve. The point where the optic nerve exits the eye is called the optic nerve head. It’s at the optic nerve head where your eye specialist will observe any damage caused by glaucoma. About 2%of New Zealanders over 40 years of age have some form of glaucoma and as risk increases with age, about 10% of New Zealanders over the age of 70 have glaucoma. Undiagnosed, it can lead to permanent vision loss, but if caught in time, and following a treatment plan, your vision can be saved.
What are the symptoms of glaucoma?
Glaucoma is often referred to as being the “thief of sight”. This is mainly due to its slow progression, and because it is initially only able to picked up in your regular eye exam. Because glaucoma causes a decrease in peripheral vision, this form of vision loss is difficult to notice in everyday life. Ultimately, the gradual loss of peripheral vision leads to tunnel-vision and is irreversible.
Different types of glaucoma
Glaucoma can be broken down into different classifications. These are primary open-angle glaucoma, angle closure glaucoma, normal tension glaucoma, developmental glaucoma and pigmentary glaucoma.
Primary open-angle glaucoma
Primary open-angle glaucoma is when a gradual increase in pressure within the eye occurs but it is not due to a narrowing of the drainage angle.
Angle-closure glaucoma is when the drainage angle is narrow and thus increasing pressure in the eye.
Normal tension glaucoma
Normal tension glaucoma is when the optic nerve is damaged even though the pressure within the eye remains within a normal range.
Developmental glaucoma occurs only in infants and children and is usually without symptoms.
Pigmentary glaucoma occurs when iris pigment granules build up in the eye and eventually block the drainage channel.
Chronic or acute glaucoma
Glaucoma can also be described as chronic or acute due to its onset and symptoms.
Chronic glaucoma is the most common form and is painless, and although this is a benefit, it makes it harder to diagnose initially. Those who suffer from chronic glaucoma usually experience a gradual vision loss causing tunnel vision, and if not caught, blindness.
Acute glaucoma, however, is usually caused by a sudden drainage angle closure. It is usually painful, and the reduction of your vision is sudden. If acute glaucoma is not treated immediately, loss of vision can be permanent.
What are the causes of glaucoma?
Glaucoma is caused by damage to the optic nerve and its fibres by an abnormally elevated pressure in the eye (intraocular pressure). In some cases, the pressure is within the normal range, but glaucoma may still develop due to the nerve being overly sensitive. The pressure usually builds up because of the imbalance between fluid production and drainage from the eye.
People aged over 60 years are more susceptible to suffering from glaucoma, as are people of African or Asian descent. If you have a family history of glaucoma, then there is a chance you’ll develop it as well. Pre-existing medical conditions such as diabetes, high blood pressure, heart disease, obesity and hyperthyroidism can all contribute to glaucoma development, as can migraines, eye injuries and long-term use of corticosteroids – especially eye drops.
How do you diagnose glaucoma?
In order to diagnose glaucoma, your eye care professional will need to perform a series of tests after taking a thorough history. The tests include checking your intra-ocular pressure which is called tonometry; viewing the optic nerve head and assessing damage which involves testing and scans that allow your eye care professional to determine any changes to the nerve and monitor any changes in the future.
An example of this is a fundus check or an OCT scan. A visual field test checks your field of view and how or if it has been affected by glaucomatous changes. Measuring corneal thickness, also known as pachymetry, is tested because this affects the pressure reading. Checking interior angles, also known as a gonioscopy, is where a mirrored lens is used to view your drainage angles and assess how open they are.
Can glaucoma be cured completely?
Unfortunately, glaucoma cannot be completely cured which is why it is optimal to have it diagnosed while you still have vision. While it can’t be cured fully, you can preserve your vision if treated in time.
Is glaucoma painful?
The most common type of glaucoma, chronic glaucoma is not painful. However, acute angle closure glaucoma can be painful. Any eye pain should be taken straight to your eye professional, as should any changes to your vision.
Can you prevent glaucoma?
Unfortunately, glaucoma cannot be prevented. But if you know your medical history, and have any of the aforementioned medical conditions or know that it runs in the family, it’s important to have regular eye checks. With regular eye checks, glaucoma can be detected earlier and a loss of sight can be prevented through good treatment and management.
How do you treat glaucoma?
Once glaucoma is diagnosed, on-going management and treatment are required for life. The aim of the treatment is to reduce the pressure inside the eyes so that there is less stress on the optic fibre nerves. This should slow down and inhibit any further nerve damage, and also prevent further vision loss. However, if treatment is stopped the glaucoma is likely to progress and cause further damage.
Medicinally, eye drops are usually the first-line treatment for glaucoma. There are various kinds of eye drops that can be used and an eye specialist can recommend the one that best suits you.
If eye drops have proven to be unsatisfactory, surgical or laser treatments are the next consideration to control the pressure inside the eye. This is not a type of laser we perform at the Wellington Eye Centre.