Understanding Diabetes in the Context of Eye
Diabetes is a serious condition, which, if left untreated can lead to heart disease, blindness, kidney failure and other life-threatening complications. Many people with diabetes have had it for between nine and 12 years before it is diagnosed. By this time many of these people will have started to develop some of the complications. But the good news is that if diabetes is detected early and well controlled, you can greatly reduce the risk of serious health problems.
What is diabetes?
Diabetes is a condition where the amount of glucose (sugar) in your blood is too high because the body cannot use it properly. This is because your pancreas does not produce any insulin, or not enough, to help glucose enter your body’s cells – or the insulin that is produced does not work properly (known as insulin resistance).
Insulin is the hormone produced by the pancreas that allows glucose to enter the body’s cells, where it is used as fuel for energy so we can work, play and is vital for life. If you have diabetes, your body cannot make proper use of this glucose so it builds up in the blood and isn’t able to be used as fuel.
There are two main types of diabetes:
Type 1 diabetes is when no insulin is produced at all. This type of diabetes is always treated with insulin injections.
Type 2 diabetes is when the body either does not produce enough insulin, or the insulin it produces does not work as well. This type of diabetes is treated with lifestyle changes, following a healthy balanced diet, increasing physical activity, and losing weight if you need to. Some people may need medications and/or insulin injections to achieve normal blood glucose levels.
Are you at risk?
Some of the risks factors associated with Type 2 diabetes are out of your control while others, such as being overweight, you can act on to reduce the risk of developing diabetes. You should ask your GP for a test for diabetes, if you:
• are over 40 years old
• A close member of your family has Type 2 diabetes (a parent or brother or sister).
• You’re overweight or have a waist circumference over 37 inches for men or over 35.5 inches for South Asian men, or over 31.5 inches for women.
• You have high blood pressure and you’ve had a heart attack or a stroke.
• You’re a woman with polycystic ovary syndrome and you are overweight.
• You have impaired fasting glycaemia (IFG) or impaired glucose tolerance (IGT).
• You’ve had high blood glucose levels during pregnancy (gestational diabetes).
• You have severe mental health problems.
The more risk factors you have, the greater your risk of having or developing diabetes.
Some things that do not cause diabetes:
• Eating sweets and sugar does not cause diabetes, but eating a lot of sugary and fatty foods can lead to being overweight.
• You cannot catch diabetes, like a cold.
• Stress does not cause diabetes although it may make the symptoms worse in people who already have the condition.
• An accident or an illness will not cause diabetes but may reveal diabetes if it is already there.
The symptoms of diabetes
The symptoms of diabetes are not always obvious. Some people with diabetes will put the symptoms down to other reasons, such as getting older or hot weather; while others may not experience any symptoms at all.
The main symptoms are:
• going to the toilet more often – especially at night
• increased thirst
• extreme tiredness
• unexplained weight loss
• genital itching or regular episodes of thrush
• slow healing wounds
• blurred vision.
The complications of diabetes
People with diabetes have a higher risk of developing complications, including:
• heart disease
• circulation problems
• nerve damage
• damage to the kidneys
The most important of all complications that diabetes can cause is the damage to eyes.
If you have diabetes, regular visits to your eye doctor for regular exams are important to avoid eye problems. High blood sugar (glucose) increases the risk of eye problems from diabetes. In fact, diabetes is the leading cause of blindness in adults age 20 to 74.
If you have eye problems and diabetes, don’t buy a new pair of glasses as soon as you notice you have blurred vision. It could just be a temporary eye problem that develops rapidly with diabetes and is caused by high blood sugar levels.
High blood sugar in diabetes causes the lens of the eye to swell, which changes your ability to see. To correct this kind of eye problem, you need to get your blood sugar back into the target range (70-130 milligrams per deciliter or mg/dL before meals, and less than 180 mg/dL one to two hours after a meal). It may take as long as three months after your blood sugar is well controlled for your vision to fully get back to normal.
Blurred vision can also be a symptom of more serious eye problem with diabetes. The three major eye problems that people with diabetes may develop and should be aware of are cataracts, glaucoma, and retinopathy.
Cataracts and Diabetes
A cataract is a clouding or fogging of the normally clear lens of the eye. The lens is what allows us to see and focus on an image just like a camera. Although anyone can get cataracts, people with diabetes get these eye problems at an earlier age than most and the condition progresses more rapidly than in people without diabetes.
If you have a cataract, there is a cloudy area in the lens of your eye that results in the inability to focus light, and your vision is impaired. Symptoms of this eye problem in diabetes include blurred or glared vision.
During cataract surgery, the cloudy lens is removed or cleaned out and replaced by a clear man-made lens.
Glaucoma and Diabetes
When fluid inside the eye does not drain properly, it can lead to excess pressure inside the eye. This results in another eye problem with diabetes called glaucoma. The increase in pressure can damage nerves and the blood vessels in the eye, causing changes in vision.
Treatment of open-angle glaucoma — the most common form of glaucoma — requires lowering the eye’s pressure by increasing the drainage of aqueous humor or decreasing the production of the fluid. Medications can accomplish both of these goals.
With open-angle glaucoma, there may be no symptoms of this eye problem at all until the disease is very advanced and there is significant vision loss. In the less common form of this eye problem, symptoms can include headaches, eye aches or pain, blurred vision, watering eyes, halos around lights, and loss of vision.
Treatment of this eye problem in diabetes can include special eye drops, laser procedures, medicine, or surgery. Surgery and laser treatments are directed at improving the eye’s aqueous drainage. You can prevent serious eye problems in diabetes problems by getting an annual glaucoma screening from your eye doctor.
People with diabetes are also more likely to get an uncommon type of glaucoma, called neovascular glaucoma. In this form of glaucoma new blood vessels grow on the iris, the colored part of the eye. These blood vessels block the normal flow of fluid out of the eye, raising the eye pressure. It is difficult to treat. One option is laser surgery to reduce the vessels. Doctors are also studying the use of implants to help drain the fluid.
The retina is a group of specialized cells that convert light as it enters though the lens into images. The eye nerve or optic nerve transmits visual information to the brain.
Diabetic retinopathy is one of the vascular (blood-vessel related) complications related to diabetes. This diabetes eye problem is due to damage of small vessels and is called a “microvascular complication.” Kidney disease and nerve damage due to diabetes are also microvascular complications. Large blood vessel damage (also called macrovascular complications) includes complications like heart disease and stroke.
The microvascular complications have, in numerous studies, been shown to be related to high blood sugar levels. You can reduce your risk of these eye problems in diabetes complications by improving your blood sugar control.
Diabetic retinopathy is the leading cause of irreversible blindness in industrialized nations. The duration of diabetes is the single most important risk for developing retinopathy. So the longer you have diabetes, the greater the risk of this very serious eye problem. If retinopathy is not found early or is not treated, it can lead to blindness.
People with type 1 diabetes rarely develop retinopathy before puberty. In adults with type 1 diabetes, it is also rare to see retinopathy before five years’ duration of diabetes. The risks of retinal damage increase with progressive duration of diabetes. Intensive control of blood sugar levels will reduce your risks of developing retinopathy. The DCCT, a large study of people with type 1 diabetes showed that people with diabetes who achieved tight control of their blood sugars with either an insulin pump or multiple daily injections of insulin were 50%-75% less likely to develop retinopathy, nephropathy (kidney disease), or nerve damage (all microvascular, or small blood vessel, complications).
People with type 2 diabetes usually have signs of eye problems when diabetes is diagnosed. In this case, control of blood sugar, blood pressure, and blood cholesterol with diabetes have an important role in slowing the progression of retinopathy and other eye problems.
Types of Retinopathy in Diabetes:
• Background retinopathy: Sometimes the blood vessel damage exists, but there is no vision problem. This is called background retinopathy. It’s important to carefully manage your diabetes at this stage to prevent background retinopathy from progressing to more serious eye disease.
• Maculopathy: In maculopathy, the person has developed damage in a critical area called the macula. Because this occurs in an area that is critical to vision, this type of eye problem can significantly reduce vision.
• Proliferative retinopathy: New blood vessels start to grow in the back of the eye. Because retinopathy is a microvascular complication of diabetes, a disease of small vessels, this type of retinopathy develops because of an increasing lack of oxygen to the eye from vascular disease. Vessels in the eye are thinned and occluded and they start to remodel.
Here, it is important to address the risks factors that can worsen the occluded vessels. Smoking cessation, high blood pressure control, cholesterol management, and blood sugar control must take place in order to stop the progression of new vessels from forming into the orbit of the eye. These are fragile vessels that can bleed and eventually cause a clot to form in the orbit, which scars and causes detachment of the retina. This eventually leads to irreversible vision loss.
Treatment of diabetic retinopathy may involve laser procedures or surgery. In a study of people with diabetes with early retinopathy, laser therapy to burn the fragile vessel resulted in a 50% reduction of blindness.
To prevent retinopathy with diabetes, have your eye doctor screen your eyes annually. Women with diabetes who later become pregnant should have a comprehensive eye exam during the first trimester and close follow-up with an eye doctor during the rest of their pregnancy to avoid serious eye problems with diabetes. (This recommendation does not apply to women who develop gestational diabetes, since they are not at risk for retinopathy.)
Preventing Eye Problems With Diabetes
Everyone should have regular eye exams, but annual eye exams are particularly important if you have diabetes. A thorough eye exam can help identify a problem early on when it is more easily treated. This can also help prevent further vision loss.
If you are considering pregnancy and have a history of diabetes, you should have an eye exam prior to and possibly during pregnancy. Ask your eye doctor what is right for you.
Also, controlling your blood sugar and blood pressure will help prevent eye problems if you have diabetes.
When to Contact Your Doctor About Eye Problems in Diabetes
If you have diabetes, contact your doctor about any eye problems in if any of the following occur:
• Black spots in your vision.
• Flashes of light.
• “Holes” in your vision.
• Blurred vision.