What is glaucoma?
Glaucoma is an eye disease that is usually the result of high pressure in the eye, causing damage to the optic nerve over time. This can lead to vision loss and, potentially, cause irreversible blindness.
Broadly classified into 3 categories, glaucoma is the second-leading cause of blindness around the world.
Primary open-angle glaucoma (POAG)
This is the most common type of glaucoma. In this form of glaucoma, there are often no symptoms other than gradual loss of peripheral vision. It happens so gradually that by the time vision loss is noticeable, it is often in the advanced stage of the disease. Hence, it is often termed as the “silent thief of sight”.
- Normal tension glaucoma
This is a subset of POAG, also known as low-tension glaucoma, where the optic nerve gets damaged though the eye pressure is within the normal range. In this form, obstructive sleep apnoea and lack of blood flow to the optic nerve can be a contributing factor.
- Congenital glaucoma
This is a rare condition that occurs in babies and young children. It may be inherited and it is caused by abnormal development of the eye’s drainage system before birth. This leads to increased intra-ocular pressure, which in turn damages the optic nerve.
Primary angle-closure glaucoma (PACG)
There are acute or chronic types in this form of glaucoma. The acute type, termed as acute primary angle closure (APAC), is caused by a rapid build-up of fluid in the eye as a result of a blockage of the angles.
It presents with sudden eye pain, blurring of vision associated with headache, nausea and vomiting. This requires immediate medical attention as it can lead to rapid loss of vision if left untreated.
The chronic form is usually asymptomatic, just like POAG.
There are notable causes such as being the result of previous injury to the eye from an accident, surgery, hyper-mature cataracts, eye tumour or medications such as corticosteroids. Uncontrolled diabetes or hypertension can also cause secondary forms of glaucoma.
Who is most at risk?
The following are known risk factors for glaucoma, but not being in these risk types does not rule one out from developing glaucoma:
The risk of developing glaucoma increases as you grow older. In Singapore, 3% of those above 50 years old and as high as 10 – 12% of those above 70 years old have glaucoma.
POAG is more prevalent in those of African-Caribbean descent as compared with Caucasians, while PACG is more common in Asians as compared to Caucasians.
Those with a first-degree relative with glaucoma may have an increased 1 in 10 risk of getting glaucoma.
Pre-existing medical conditions
Heart disease, high blood pressure and diabetes are all risk factors for glaucoma.
Extended use of certain medications
Medicines, such as the extended use of corticosteroids in any form, can increase eye pressure and cause glaucoma.
Conditions leading to increased pressure in the eye
Past injury to the eye or chronic eye inflammation can lead to increased eye pressure and glaucoma as well.
When should I see a doctor?
A doctor, preferably an ophthalmologist, should be consulted should any changes or abnormalities occur with the eyes.
However, since glaucoma is usually asymptomatic, one should go for eye screening once you reach 50 years of age. If you have any risk factors for glaucoma as mentioned above, screening should start at the age of 40 years old. Thereafter, your ophthalmologist will advise you on the frequency of the follow-ups which can range from 1 – 2 years, or sooner if there are any concerns.
You should see an eye doctor immediately if you experience the symptoms below as you could be having an acute angle closure attack:
- sudden severe eye pain with eye redness
- sudden vision disturbances or blurred vision
- seeing coloured rings or halos around lights
- headache, nausea or vomiting accompanying eye pain
Can glaucoma be cured?
While there is no cure for glaucoma, the disease can be kept under control and vision loss slowed or even stopped if the pressure in the eye is well-controlled. However, any vision that has been lost will not be restored, and lifelong treatment and follow-ups will be required to ensure that the disease is kept under control.
What are the treatment options for glaucoma?
At first diagnosis, your ophthalmologist will help to reduce your eye pressure to halt any further vision loss or deterioration. This can be achieved with the use of eye drops or medications. Some patients may require laser or surgery if the eye pressure cannot be controlled adequately with medications.
In the case of an acute angle closure attack, which is a medical emergency, the high eye pressure will need to be lowered immediately with medications. The ophthalmologist will then perform a laser peripheral iridotomy. In this procedure, laser is used to create a small hole in the iris tissue to allow for fluid movement from behind the iris to the front chamber of the eye. The other eye, which may be at risk, will likely require a prophylactic laser peripheral iridotomy as well to prevent a future attack.
How can the risks be reduced?
The best way to minimise vision loss is to detect glaucoma early through annual eye tests, as early glaucoma often has no symptom at all. Consult an ophthalmologist to book an annual eye check-up.
Should worrying changes in the eyes or vision be noticed, do not delay seeing a doctor for an accurate diagnosis and appropriate treatment plan.
Article reviewed by Dr Tan Yar Li, ophthalmologist at Gleneagles Hospital
Glaucoma. Retrieved 16/7/20 from https://www.healthline.com/health/glaucoma
Glaucoma. Retrieved 16/7/20 from https://www.webmd.com/eye-health/glaucoma-eyes#1