Cataracts
Cataracts are cloudy patches in the lens (the transparent structure at the front of the eye) that can make vision blurred or misty. They can develop in one or both eyes, and one eye can often be more affected than the other.
The lens is normally clear and allows light to pass through to the back of the eye. However, if parts of the lens become cloudy (opaque), light is unable to pass through the cloudy patches.
Over time, the cloudy patches usually become bigger, and more of them develop. As less light is able to pass through the lens, the person’s vision is likely to become blurry or cloudy. The cloudier the lens becomes, the more the person’s sight will be affected.
Cataracts are the main cause of impaired vision in the world, particularly in developing countries. They affect men and women equally.
Cataracts most commonly affect older people. Cataracts that affect older people are known as age-related cataracts. In the UK, it is estimated that more than half of people who are over 65 years of age have some cataract development in one or both eyes.
In rare cases, babies have cataracts when they are born, or children develop them at a young age. See the Health A-Z topic about Childhood cataracts for more information.
If cataracts are mild, stronger glasses and brighter reading lights may enable people to live with the condition. However, if left untreated, cataracts can cause blindness.
Once cataracts start interfering with daily activities such as cooking or getting dressed, surgery is usually recommended. It is estimated that around 10 million cataract operations are performed around the world each year. Cataract operations are generally very successful with few complications.
If you have cataracts, it could affect your ability to drive. It is your legal obligation to inform the Driver and Vehicle Licensing Agency (DVLA) about a medical condition that could have an impact on your driving ability. The Directgov website has advice about how to tell the DVLA about a medical condition.
(Source/Further information:: www.nhs.co.uk, http://www.nei.nih.gov)
Normal Vision
Vision with a Cataract
Glaucoma
Glaucoma is a term that describes a group of eye conditions that affect vision. Glaucoma often affects both eyes, usually in varying degrees. One eye may develop glaucoma quicker than the other.
If left untreated, glaucoma can cause blindness. But if it is diagnosed and treated early enough, further damage to vision can be prevented
Glaucoma occurs when the drainage tubes (trabecular meshwork) within the eye become slightly blocked. This prevents eye fluid (aqueous humour) from draining properly.
When the fluid cannot drain properly, pressure builds up. This is called intraocular pressure. This can damage the optic nerve, which connects the eye to the brain, and the nerve fibres from the retina (the light-sensitive nerve tissue that lines the back of the eye).
There are four main types of glaucoma:
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Chronic open-angle glaucoma: this is the most common type of glaucoma and develops very slowly.
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Primary angle-closure glaucoma: this is rare and can occur slowly (chronic) or may develop rapidly (acute) with a sudden, painful build-up of pressure in the eye.
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Secondary glaucoma: this occurs as a result of an eye injury or another eye condition, such as uveitis (inflammation of the middle layer of the eye).
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Developmental glaucoma (congenital glaucoma): this is rare but can be serious. It is usually present at birth or develops shortly after birth. It is caused by an abnormality of the eye
In England, about 480,000 people have chronic open-angle glaucoma. Among white Europeans, about 1 in 50 people above 40 years old and 1 in 10 people above 75 years old has chronic open-angle glaucoma. It may be more common among people of black-African or black-Caribbean origins.
The other types of glaucoma are much less common. Among white people, acute angle-closure glaucoma may affect about 1 in 1,000 people. It is more common among people of Asian origin, affecting around 1 in 100 of them.
Glaucoma can be treated with eye drops, laser treatment or surgery (see Glaucoma - treatment). However, early diagnosis is important because any damage to the eyes cannot be reversed. Treatment aims to control the condition and minimise any future damage.
Attending regular optician appointments will help to ensure that any signs of glaucoma can be detected early and allow treatment to begin. Without treatment, glaucoma can eventually cause blindness.
(Source/Further information:: www.nhs.co.uk, http://www.nei.nih.gov)
Optic Nerve
Normal Vision
Glaucoma Vision
Diabetic Retinopathy
Diabetic retinopathy is a complication of diabetes in which the retina, a part of the eye, becomes progressively damaged.
During the initial stages, diabetic retinopathy does not cause any symptoms. However, if it is not treated it can cause partial, followed by total, loss of vision.
Diabetes is a condition in which the body does not produce enough insulin or cannot use insulin properly. Insulin is a hormone that helps break down glucose (sugar) so that it can be used by the body’s cells as fuel.
The body's problem with making or using insulin causes the level of glucose in the blood to rise. This can cause a wide range of complications, including diabetic retinopathy.
There are two types of diabetes, which are described below.
In type 1 diabetes, the body does not produce any insulin. The condition usually begins in people who are under 40 years of age and often develops during the teenage years. People with type 1 diabetes will need injections of insulin for the rest of their life.
Type 2 diabetes is where the body does not produce enough insulin to function properly or where the body’s cells do not react to insulin.
Being overweight or obese is a major risk factor for type 2 diabetes. Type 2 diabetes can develop at any age, but usually affects people who are 45 years of age or over. Some people with type 2 diabetes can control their symptoms using a combination of diet and exercise. More serious cases require insulin injections.
Type 2 diabetes is the most common type of diabetes, accounting for 95% of all cases.
Diabetic retinopathy is a common complication of diabetes. It is the leading cause of blindness in adults under the age of 65.
It is estimated that 25% of people with type 1 diabetes will have some degree of diabetic retinopathy five years after their symptoms first develop.
In the case of type 2 diabetes, 25% of people who do not require insulin will have some degree of diabetic retinopathy five years after the onset of symptoms. The figure is higher for people who require insulin (an estimated 40%).
If diabetic retinopathy is diagnosed and treated at an early stage, the outlook for the condition is good. Research has found that treatment can prevent severe vision loss in 90% of cases of diabetic retinopathy.
Early stage diabetic retinopathy can usually be treated by bringing your diabetes under better control. More advanced diabetic retinopathy will require laser surgery to prevent further damage to the eyes.
The Department of Health has set up a national screening (testing) programme for diabetic retinopathy. If you are 12 years of age or over and you have diabetes, you should be offered annual screening.
The screening programme was introduced because, if diabetic retinopathy is detected early enough, it can be treated effectively using laser treatment.
By the time diabetic retinopathy begins to cause noticeable symptoms, it is often much harder to treat.
You should receive a letter from your GP or healthcare professional inviting you to attend a screening appointment. Contact your GP if you think that you are overdue for a screening appointment.
During screening, eyedrops are used to make your pupils large and photographs of your retina are taken. As the photographs are being taken, you will see flashes of bright light, but usually it is not uncomfortable.
The eyedrops may cause your eyes to sting slightly and your vision may become blurred about 15 minutes after the procedure ends. The blurring can last between two and six hours, depending on what sort of eyedrops were used.
The blurring will affect your ability to drive, so you will not be able to drive home from your screening appointment. You will also find that everything looks very bright, so you may want to take sunglasses to your appointment.
In very rare cases, the eyedrops can cause a sudden rise in pressure within your eye. However, this only occurs in people who are already at risk of developing the condition. If it occurs, prompt treatment in an eye unit will be required.
In rare cases, the screening procedure may cause:
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pain or severe discomfort in your eye
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redness of the white of your eye, or
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constant blurred sight, sometimes with rainbow haloes around lights
If, after screening, you experience any of the symptoms above, contact your screening centre or go to an accident and emergency (A&E) department.
You will not receive the results immediately after the procedure because the pictures will need to be studied by a team of healthcare professionals. The screening staff should tell you how long this will take.
You will be called back for a further assessment if:
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staff find sight-threatening retinopathy that requires follow-up treatment
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the degree of retinopathy needs checking more than once a year
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the photographs are not clear enough to give an accurate result, or
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other eye conditions, such as glaucoma or cataracts, are detected by chance (screening for retinopathy will not always detect other eye conditions)
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The screening programme is not compulsory, but if you have diabetes it is the single best way to prevent sight loss.
If diabetic retinopathy is detected during screening, you will be given information about how far the condition has progressed. This will determine the type of treatment you will receive.
The stages of diabetic retinopathy are described below.
Background retinopathy is the first stage of diabetic retinopathy. There is evidence of microaneurysms (tiny bulges in blood vessels) and some mild bleeding.
Pre-proliferative retinopathy is the second stage. By this stage, new blood vessels have started to form in the retina and there are multiple points of bleeding.
Maculopathy is the third stage. By this time, the macula (the most sensitive part of the retina) has been damaged.
Proliferative retinopathy is the most advanced stage. The formation of new blood vessels has increased, there is evidence of scar tissue and there may be some degree of retinal detachment.
(Source/Further information:: www.nhs.co.uk, http://www.nei.nih.gov)
Healthy Retina
Severe Diabetic Retinopathy
Age Related Macular Degeneration (ARMD/AMD)
Macular degeneration is a painless eye condition that leads to the gradual loss of central vision (the ability to see what is directly in front of you). Central vision is used while:
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reading
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writing
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driving
Macular degeneration occurs when the macula (the part of the eye that is responsible for central vision) is unable to function as effectively as it used to.
Macular degeneration does not affect the peripheral vision, which means that the condition will not cause complete blindness. The peripheral vision, sometimes known as "side vision", is the outer vision.
There are two types of macular degeneration:
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Dry macular degeneration (also called non-neovascular) affects the eyes gradually.
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Wet macular degeneration (also called neovascular) can develop very quickly, and is more serious than dry macular degeneration.
Around 90% of cases of macular degeneration are dry.
Macular degeneration most commonly affects people who are over 50, and is referred to as age-related macular degeneration (AMD). Around 30% of people who are over 75 have early signs of AMD, and about 7% have more advanced AMD.
For reasons that are not fully understood, AMD tends to be more common in women than in men. There are also a number of other factors, such as smoking, that can increase the risk of developing AMD.
Macular degeneration in young people is rare, and is usually caused by a genetic condition.
Although AMD is the leading cause of visual impairment in the UK, almost everyone affected will have enough peripheral vision to continue their daily activities.
There is currently no treatment for dry macular degeneration, but techniques such as using magnifying lenses to read can help people to live with the condition. Dry AMD progresses slowly, over several years.
Wet AMD is more serious. It is estimated that around 70% of people with wet AMD will experience severe loss of vision within two years of receiving their diagnosis.
There are several treatment options available that can slow the progression of wet AMD and, in some cases, restore some of the lost vision. Treatment must be started as soon as possible.
(Source/Further information: www.nhs.co.uk)
Healthy Retina
Age Related Macular Degneration
Amsler Grid Result With AMRD