Watch out! Having diabetes can injure your eyes severely - Part I

Watch out! Having diabetes can injure your eyes severely - Part I

Having too much sugar in your blood can injure many parts of the body, including your heart, kidneys -- even your eyes.

Diabetes is a serious disease, but if an individual adopts healthy lifestyle habits, complications can be prevented.

It's important to check your blood sugar levels regularly and make sure you lower it if necessary. Too high of a blood sugar level, especially over a prolonged period, can damage many areas of the body.

Insofar as the eyes are concerned, diabetes can damage the blood vessels in your eyes.

This damage can lead to glaucoma, cataracts, structural changes to your retina, even blindness.

When blood vessels are damaged, nerve signals can't reach your eyes.

In addition, having diabetes can lead to a buildup of pressure from fluid, which can compress nerves and other structures in your eyes.

Given the above information, it is essential to know how your eye works.

When we look at something, light passes through the front of the eye, and is focused by the lens onto the retina. The retina is a delicate tissue that is sensitive to light. It converts the light into electrical signals that travel along the optic nerve to the brain. The brain, in turn, interprets these signals to "see" the world around us. The retina is supplied with blood by a delicate network of blood vessels.

These blood vessels can be damaged by diabetes.

Light is focused onto an area of the retina called the macula, which is about the size of a pinhead. This highly specialised part of the retina is vital, because it allows you to see fine detail for activities such as reading and writing, and to recognise colours.

The rest of the retina gives you side vision (peripheral vision). The eye is filled with a clear jelly-like substance called the vitreous gel. Light passes through the gel to focus on the macula.

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 can go cloudy and 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.

In 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.

In diabetic retinopathy, the blood vessels in the retina are only very mildly affected, they may bulge slightly (microaneurysm) and may leak blood (haemorrhages) or fluid (exudates).

As long as the macula is not affected, vision is normal and you will not be aware that anything is wrong.

Your retinal screening test will keep a close check on these early changes and ensure that any signs of progression to more serious stages of retinopathy are detected early.

Maculopathy means that your macula is affected by retinopathy.

If this happens, your central vision will be affected and you may find it difficult to see detail such as recognising people's faces in the distance or seeing detail such as small print.

Most maculopathy can be treated with laser with the aim of preserving as much vision as possible. The amount of central vision that is lost varies from person to person. However, the vision that allows you to get around at home and outside (peripheral vision) is not affected.

If diabetic retinopathy progresses, it can cause the larger blood vessels in the retina to become blocked. These blockages can result in areas of the retina becoming starved of oxygen. This is called ischaemia. If this happens the eye is stimulated into growing new vessels, a process called neo-vascularisation.

This is the proliferative stage of diabetic retinopathy, and is nature's way of trying to repair the damage by growing a new blood supply to the oxygen starved area of your retina.

Unfortunately, these new blood vessels are weak, and grow in the wrong place - on the surface of the retina and into the vitreous gel. As a result, these blood vessels can bleed very easily which may result in large haemorrhages over the surface of the retina or into the vitreous gel. These types of haemorrhages can totally obscure the vision in the affected eye as light is blocked by the bleed. With time the blood can be reabsorbed and vision can improve.

Extensive haemorrhages can lead to scar tissue forming which pulls and distorts the retina. This type of advanced diabetic eye disease can result in the retina becoming detached with the risk of serious sight loss.

Only between 5 and 10 per cent of all diabetics develop proliferative retinopathy. It is more common in people with type 1 diabetes than type 2. Sixty per cent of type 1 diabetics show some signs of proliferative disease after having diabetes for 30 years.

The following action reduces your risk of developing retinopathy or helps to stop it from getting worse:

• controlling your blood sugar (glucose levels)
• tightly controlling your blood pressure
• controlling your cholesterol levels
• keeping fit, maintaining a healthy weight and giving up smoking are all part of good diabetes control. Nerve damage, kidney and cardiovascular disease are more likely in smokers with diabetes. Smoking increases your blood pressure and raises your blood sugar level which makes it harder to control your diabetes
• regular retinal screening (see more below). The most effective thing you can do to prevent sight loss due to diabetic retinopathy is to attend your retinal screening appointments. Early detection and treatment prevents sight loss.

Risk factors that cannot be controlled:

• the length of time you have had diabetes. This is a major risk for developing diabetic retinopathy
• your age affects the progression of diabetic retinopathy
• your ethnicity. Studies have suggested higher levels of diabetic retinopathy in certain ethnic groups, while other work has suggested that these differences are due only to social factors.

Most complications can be treated, but it is vital that they are diagnosed early. They can only be detected by a detailed examination of the eye carried out at a specialist screening centre.

Source: ANI