What is Glaucoma?
Glaucoma is an eye disease that kills the nerves in your eyes till you lose your entire vision. The most common form of Glaucoma can creep in so slowly without you even realising because it is painless and the visual symptoms are not perceptible till it is quite severe.
Glaucoma is caused by the elevation of the pressure within the eye. It is called the Intra-Ocular Pressure (IOP). Just like how excessive blood pressure is bad for one’s general health, high IOP usually spells danger for our visual health.
A normal healthy eye – A clear fluid, Aqueous Humour, produced from the back of the Iris flows to the front of the Iris with nutrients to the back of the cornea. It also helps to regulate IOP as low IOP will cause the eye ball to collapse on itself. This fluid is drained out of the eye through a drainage system primarily through the trabecular meshwork. Equal amounts of fluid produced to equal amounts of fluids drained out keeps the IOP steady and the eye healthy.
There are a few forms of Glaucoma, we will look at a few of the most common ones in decreasing occurrence.
1) Primary Open Angle Glaucoma (POAG) – This is when the trabecular meshwork starts malfunctioning and the drainage of the fluid slows down. The fluid starts to accumulate and the pressure starts to build within the eye. This pressure starts to press our delicate nerves and over time the nerves start to die, slowly. Unfortunately, our nerve cells do not regenerate. The nerve cells furthest from the optic nerve and macular die first, resulting in the loss of our most extreme peripheral vision. Most people are not sensitive enough to notice this loss. Slowly the cell death starts to creep towards the macular which is in charge of our central vision. When the death of nerve cells reaches the macular, one is left with just the central most vision.
2) Normal Tension Glaucoma – In this form of Glaucoma, the IOP remains within normal limits (Below 21mmHg) but the pressure somehow starts to kill the nerve cells in the same pattern. This makes it even more difficult to diagnose early. The pattern of vision loss is the same as POAG.
3) Acute Angle Closure Glaucoma (AACG) – In AACG, the gap between the Iris and the cornea closes/narrows unexpectedly. The sudden shutting of the drainage system will cause the IOP to skyrocket causing extreme pain, nausea, blurry vision and a headache. This is a Medical Emergency. Rush yourself to the nearest A&E. If you have access to a can of the sweetest drink available, gulp it down and get into a bright room. These actions will cause the pupils to constrict and widen the gap between the Iris and the Cornea. If untreated, permanent blindness is a real possibility.
Glaucoma can also occur at birth and also secondary to other eye diseases or eye surgeries.
Am I at risk?
Singapore’s leading cause of blindness is Glaucoma at 40% of all permanent vision loss. It is advisable to go for annual eye examinations to ensure every part of the visual system is working as it should be. But extra precaution must be taken by those in the following categories.
- People over 60 – 10% of all Singaporeans are diagnosed with Glaucoma after the age of 70
- Asians – Asians also have a higher tendency to get AACG
- Steroid users
- People who had a previous eye injury
Glaucoma is a very serious eye disease which causes irreversible vision loss. Please practice due diligence in caring for your vision. Visit an Ophthalmologist to get your eye health assessed bi-annually at the least.
Stay Healthy & Stay Happy!