Eye Conditions Explained
Age-Related Macular Degeneration (AMD)
Age-related macular degeneration is a condition of the eye that affects a very small part of the retina at the back of your eye, called the macula. AMD causes problems with your central vision, but does not lead to total loss of sight and is not painful. AMD affects the vision used when you are looking directly at something, e.g. when you are reading, watching television or looking at photographs. AMD may make this central vision blurry or distorted and may, over time, cause a blank patch in the centre of your vision.
Types of AMD
AMD comes in two main variations – ‘wet’ AMD and ‘dry’ AMD. The reason that they are called ‘wet’ and ‘dry’ is because of what happens inside your eye and what the ophthalmologist sees when the inside of your eye is examined and not because of how the eye feels or whether you have a watery or dry eye.
Approximately 10-15% of people with AMD have wet AMD. It is developed when the cells of the macula cease to work properly causing the body to start growing new blood vessels in order to fix the problem. Unfortunately, the new blood vessels grow in the wrong place, causing swelling and bleeding below the macula. This growth of new blood vessels, known as neo-vascularisation, causes additional damage to your macula which will eventually lead to scarring. Both the new blood vessels and the scarring will damage your central vision and usually leads to a blank patch in the centre of your sight.
Dry AMD is the most common type. Usually, it develops very slowly and will cause a gradual change to your central vision. Dry AMD often takes a number of years before it reaches its final stage. In the most extreme cases, dry AMD can cause a blank patch at the centre of your vision, in both eyes. However, it doesn’t affect your peripheral vision, so does not lead to total blindness.
For more in depth information goto The RNIB website
Cataracts are a very common eye condition. As our bodies grow older the lens inside our eye will gradually change and become less transparent. A lens that has turned misty, or cloudy, in this way is described as having a cataract. Over the course of time a cataract can get gradually worse, making your vision mistier and less clear. Often, a simple operation can be carried out which will remove the cloudy lens and replace it with an artificial one, thus, allowing you to see more clearly once more. For more information goto The RNIB website
Glaucoma is used to describe a group of eye conditions that cause damage to the optic nerve and can consequently affect your eye sight. Glaucoma damages the optic nerve at the point where it leaves your eye. Glaucoma damage is most often caused through raised eye pressure and a weakness in the optic nerve. Though it is possible to have an eye pressure within normal limits and for damage to occur if there is a weakness in the optic nerve. In most cases, high pressure and optic nerve weakness are both involved. Note that your eye pressure is in no way connected to your blood pressure.
Your eye needs a certain degree of pressure to maintain the shape of the eyeball, allowing it to work correctly. However, if the optic nerve comes under too much pressure then it can be damaged. The level of damage that occurs is dependent on how high the pressure is and for how long it lasts, and whether there are any weaknesses of the optic nerve, such as a poor blood supply. Very high eye pressure can cause damage to the optic nerve immediately. A lower level of pressure will cause the damage to your eye to occur more slowly, thus gradually losing your sight if the condition is not treated.
Acute Angle Closure Glaucoma
Acute glaucoma is much less common than Primary Open Angle Glaucoma. Acute Angle Closure Glaucoma occurs when there is a sudden and more complete blockage to the flow of aqueous fluid from the eye. This is nearly always very painful and causes permanent damage to your sight if not treated correctly.
In acute angle closure glaucoma, the pressure in the eye rises rapidly. This is because the outer edge of the iris and the front of the eye (cornea) come into contact, which stops the aqueous fluid from draining away through the trabecular meshwork as normal. This can happen in one or both eyes but it is rare for both eyes to have an attack at the same time.
Symptoms of acute glaucoma
In the early stages you may see misty rainbow-coloured rings around white lights. But for most people sudden increase in eye pressure is very painful. The affected eye becomes red, the sight deteriorates and you may even black out. You may also feel nauseous and be sick. Acute glaucoma is an emergency and needs to be treated quickly if sight is to be saved.
Some people can experience a series of mild attacks, often in the evening. Vision may seem “misty” with coloured rings seen around white lights and there may be some discomfort in the eye. If you think that you’re having mild attacks you should have your eyes tested as soon as possible and let the optometrist know that you’re having these symptoms.
In some people, the angle between the cornea and the iris is narrow, meaning there could be more risk of developing closed angle glaucoma. Your optometrist may notice this during your eye test and may refer you to the hospital for further tests and treatment even if you have no symptoms of acute glaucoma.
For more information goto The RNIB website
Diabetes And Your Eye
Diabetes can affect your eye in a number of ways:
- The most serious eye condition associated with diabetes involves the network of blood vessels supplying the retina. This condition is called diabetic retinopathy.
- The unusual changes in blood sugar levels resulting from diabetes can affect the lens inside the eye, especially when diabetes is uncontrolled. This can result in blurring of vision which comes and goes over the day, depending on your blood sugar levels.
- A longer term effect of diabetes is that the lens of your eye can go cloudy, This is called a cataract.
Not everyone who has diabetes develops an eye complication. Of those that do, many people have a very mild form of retinopathy which may never progress to a sight threatening condition.
The most serious complication of diabetes for the eye is the development of diabetic retinopathy. Diabetes affects the tiny blood vessels of the eye and if they become blocked or leak then the retina and possibly your vision will be affected. The extent of these changes determines what type of diabetic retinopathy you have. Forty per cent of people with type 1 diabetes and twenty per cent with type 2 diabetes will develop some sort of diabetic retinopathy.
For more information goto The RNIB website.
Flashes And Floaters
Floaters look like small, dark spots or strands that appear to float in front of your eyes. Floaters are very common and are normally harmless. They are more common if you are short sighted or as you get older.
Some people notice they see flashes of light. These can be due to movement of the gel inside the eye.
Very occasionally, flashes or an increase in floaters can be a sign of a retinal detachment, which needs treating as soon as possible. This is more common as you get older, or in people who are short sighted or have had eye surgery.
Other Useful Links
Click here to access The College of Optometrists website which holds up-to-date information on eye and vision health and common conditions