07 January 2020
All about glaucoma
Glaucoma is a condition whereby your eyesight gradually deteriorates as a result of damage to your optic nerve. The optic nerve is at the back of your eye and becomes damaged by a build-up of pressure inside the eye – primarily due to issues with the eye’s draining area. Your eyes constantly produce a watery fluid called aqueous to maintain good eye pressure and nourish the cornea, keeping your eyes healthy and promoting good vision. Your eye’s drainage area, also known as the drainage angle or simply just “the drain”, is what controls the outflow of the aqueous. It is a mesh-like structure, meaning that it can easily become blocked. The rate at which the aqueous is produced and leaves the eye contributes to healthy eye pressure.
Glaucoma occurs when the drainage angle in the eye is either completely blocked or partially blocked, preventing the aqueous from draining properly. This causes eye pressure to build, damaging the optic nerve and impairing peripheral vision. There are two main types of glaucoma: open angle and closed angle. If the aqueous can reach the drainage angle, it is called open angle glaucoma as the drain is still accessible. The issue here is primarily with how the liquid drains. If drainage angle is blocked, preventing the aqueous from passing through, it is called closed angle glaucoma.
Types of glaucoma
Open-angle glaucoma, discussed above, is the most common type of the condition. The eye’s drain structure may look normal, but doesn’t function properly and the liquid doesn’t leave the eye as it should. Closed angle glaucoma is more common in Asia than in other parts of the world, raising questions about people’s genetic predisposition to developing different forms of glaucoma. The blocked drainage angle that comes with this form of glaucoma causes a sudden, dangerous build-up of pressure, due to a blocked drainage angle.
There are three other types of glaucoma which are less common: secondary glaucoma, normal-tension glaucoma, and pigmentary glaucoma. Their names tend to give a good indication of their causes. Secondary glaucoma occurs as a result of a primary condition causing a build-up of pressure in your eye. This is typically due to cataracts or diabetes, and isn’t necessarily related to a genetic predisposition.
Normal-tension glaucoma occurs when, as the name suggests, your eye pressure is still within the average range. Instead of resulting in loss of peripheral vision, there are smaller blind spots occurring due to a damaged optic nerve. It has been suggested that this is a sub-type of open angle glaucoma. Finally, there is pigmentary glaucoma. Sometimes your iris (the coloured section of your eye) produces small bits of pigment which can come loose and enter the aqueous. These then clog the mesh-like drainage angle inside your eye, leading to high pressure and development of glaucoma.
Who is at greater risk of developing glaucoma?
There are certain groups of people whose risk factor for glaucoma is much higher than other members of the population. First and foremost, age is a key factor with adults in their 70s and 80s at highest risk. Research has found that you are more likely to develop a form of glaucoma if you fall into one of the below categories:
- African, Irish, Russian, Japanese, Hispanic, Inuit or Scandinavian descent
- Aged over 40
- Severely short-sighted or long-sighted
- Family history of glaucoma
- Have cataracts
- High blood pressure
- Thin corneas
- Suffered from an eye injury
Everyone should visit their opticians regularly to have all aspects of their eye health checked but, if you meet any of the above criteria, it is especially important for you to attend eye appointments. Glaucoma is often called “the silent thief of sight” because its symptoms usually go entirely unnoticed until irreversible damage to your vision has already been done. Without any pain or deterioration in the quality of your vision, there is no way for you to know about the disease in your eyes other than by having it checked out and identified by a professional.
What are the symptoms?
As previously mentioned, glaucoma infamously has few symptoms. Open angle glaucoma usually has none at all, while closed angle glaucoma has a few such as blurry vision, halos when looking at lights, eye pain and nausea. One of the key signs that glaucoma may be developing is if you have high eye pressure – this suggests an issue with the amount of aqueous in your eye. Your optician will measure your eye pressure and, ideally, the reading should be lower than 21 mmHg (millimetres of mercury). All About Vision suggests that “if your IOP [intraocular pressure] is higher than 30 mmHg, your risk of vision loss from glaucoma is 40 times greater than someone with intraocular pressure of 15 mmHg or lower”. It is this elevated eye pressure that damages the optic nerve at the back of the eye.
One of the most well-known symptoms of glaucoma is loss of peripheral vision however, by the time you notice this, it is likely that irreversible damage has already been done. However, treatment can usually mitigate the effects and prevent any further vision loss. Should you notice any changes to your peripheral vision, contact your eye doctor immediately.
Sometimes, in severe cases of glaucoma, you might experience an acute attack. This occurs when the iris is too close to the eye’s drain and blocks it entirely. This, in turn, leads to a sudden rise in eye pressure, often resulting in total loss of vision. Symptoms of an acute attack are:
- Vision loss
- Eye redness
- Vomiting and nausea
- Eye pain
- Halos around bright lights
If you have any combination of these symptoms, seek help from a professional immediately. The sooner you act, the more of your vision can potentially be saved.
Can glaucoma be treated?
Thankfully, as the years go by, research into glaucoma and how to treat it improves all the time. There are a range of treatments available to minimise the effects of glaucoma and save thousands of people’s sight. Eye drops are available to reduce the amount of aqueous in your eyes, or to increase the rate at which it flows out. This works to lower your eye pressure which is they key cause of glaucoma. Oral medication is another option, again aiming to reduce the amount of fluid produced in your eye. This can also improve the drainage, lowering your overall eye pressure.
There are also surgical procedures which work to reduce eye pressure and the symptoms of glaucoma and, while we do not offer them here at Optimax, they are crucial in glaucoma emergencies. Laser surgery (a different procedure to corrective laser eye surgery) serves multiple purposes: opens the drainage area, makes a hole in the iris to help the aqueous flow, or can lower overall fluid production. Alternatively, there is something called microsurgery which “creates a new channel to drain the fluid and ease eye pressure”, although this procedure is more invasive and can result in infections and potential vision loss. Ideally, glaucoma will be treated much sooner than the point at which this surgery becomes necessary.
Essentially, it’s important for you to have regular eye checks, particularly if you’re in the high risk group for developing glaucoma. Make sure you’re aware of the symptoms, and taking steps to lower your blood pressure – and therefore eye pressure – could go a long way to preventing glaucoma from taking hold.