Glaucoma is a common group of eye conditions. It is particularly dangerous because it often has little or no symptoms until it is too late. Fortunately, regular sight tests will allow for it to be detected and treated at the earliest possible stage. Glaucoma affects our peripheral vision, and since it is a very slow process, it is understandable that people do not tend to notice that anything is wrong. Left untreated, it can result in severe tunnel vision.
Why are my intraocular pressures important?
The fluid at the front of the eye (between the coloured iris and the clear cornea) is called the aqueous humour. This fluid is used to keep the cornea nourished and healthy. Because it is contained within your eye there needs to be a correct balance of new aqueous being produced and old aqueous being taken away.
Think of your kitchen sink with the tap running. If you leave the sink unplugged, there will be a steady flow of fresh water coming out of the tap and old water flowing down the plughole. If the plug were to suddenly become blocked, the sink would start to fill with water and there would be nowhere for the water to go.
Something similar happens in glaucoma, in that the aqueous is not able to flow away and so remains in the eye. This results in the pressure of the eye going up. The pressure presses on the eye and whilst you cannot feel this, it begins to damage the soft and sensitive optic nerve at the back of the eye.
The optic nerve is made up of millions of tiny fibres and these carry all the information from your eyes that make up your vision. If these become damaged, then your vision will be affected. In this case, the fibres relating to your peripheral vision are damaged and this in turn causes the loss in peripheral vision.
So what are the treatment options?
Whilst there is no cure for glaucoma as such, the aim of the medication is to reduce the pressure in the eye and prevent the damage from continuing. These work in a variety of ways but all are designed to lower the pressure. Sometimes a combination of drops may be used, or sometimes a minor laser procedure may be done by an eye consultant at the hospital which will also help lower the pressure.
Can I do anything to prevent it?
Regular sight tests! Whilst there is nothing you can do or take to prevent glaucoma from occurring, a regular sight test will allow your optometrist to detect the earliest possible changes and refer you on to a specialist before it may even have started to cause you any noticeable problems.
What are the different types of glaucoma?
There are different causes for the pressure to rise in the eye and this affects which type of glaucoma you have. Sometimes the gap between the cornea and the coloured iris is very narrow. This means that the drains where the aqueous leaves the eye become blocked and this causes the pressure to rise dramatically. This is referred to as angle closure glaucoma.
If the angle between these two is wide open, the aqueous can reach the drainage structures but they may be blocked for some other reason. This is referred to as open angle glaucoma.
My pressures are high – do I have glaucoma?
Not necessarily. The pressure required to damage the optic nerve is individual for everyone. We have a range of “normal” pressures, but this does not mean that if your pressure is outside of this range you have or will have glaucoma. Similarly if your pressures are within this “normal” range you can still develop glaucoma.
It depends on how sensitive your optic nerve is. If you have a very tough optic nerve, the pressure can still be very high and yet it does not get damaged by glaucoma. Also, you may have a very sensitive optic nerve, and whilst the pressure may be considered “normal” it may still be too high for your eye and so the pressure will need to be dropped before any damage occurs.
So what can Davis Optometrists do?
Firstly, a regular sight check will allow us to monitor your vision and ocular health, but specifically for glaucoma we can look closely at:
- Your intraocular pressure
- Your peripheral vision
- Your optic nerve health
By having regular checks we are able to determine changes at the earliest opportunity. It is always recommended that you try to stay with the same Optometrist if possible as they will have your records from before. With conditions like glaucoma it is often just as important to look at your notes from previous visits to see any subtle changes.
Importantly, we have a 3D OCT machine. This works much like an ultrasound machine in that it allows us to look at the layers underneath the retina, but also look at the optic nerve. This machine is very advanced and only normally found in the hospitals so to be able to have it performed as part of your standard sight test is very useful when checking your eye health.
Because we can look at your optic nerve in 3D, we are able to inspect it closely and monitor it carefully, helping us to safeguard the health of your eyes.