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Clinic d’Optométrie de
Hawkesbury

Optometry Clinic

 

Interesting diabetic research and the importance of A1C TESTING...

Specialists in diabetes argue that, when determining if someone has diabetes or is at risk, another test should be used as well or instead of the fasting sugar level test. The test they recommend is called glycated haemoglobin (A1C Test) and is a reliable reflection of your sugar levels over the past three months.

According to updated guidelines if you take 100 people with diabetes, every year five will have a heart attack, two will have a stroke, one will lose a leg, one will go onto dialysis and one will go blind.

Image of Non Proliferative Diabetic Retinopathy

These figures are almost certainly lower with good treatment but even so that's a lot of people at major risk given there are tens of thousands of people with diabetes, many of whom actually don't even know they've got it.

Which is why having reliable ways of detecting people who are at risk of diabetes is so crucial because it's likely that the earlier you get on top of exercise, nutrition and other risk factor reduction, the better. The standard way of diagnosing diabetes risk is taking blood and measuring the sugar, the glucose level, if it's a fasting sample and your glucose is over 7 that's diabetes. If it's over 5.5 though you're still at significant risk. You may have pre-diabetes. But there are problems relying on the blood sugar. It varies a lot so one result may falsely worry or reassure you.

Which is why specialists in diabetes have been arguing for some time that another test should be used as well or instead of the fasting sugar level. It's called glycated haemoglobin or HbA1C. It's a reliable reflection of your sugar levels over the past three months. People with diabetes will recognise the name because they use it regularly to check how well their blood sugar is under control.

Eye examinations are covered in Ontario by OHIP and patients are encouraged to be carefully examined with a comprehensive dilated examination annually.

Retinal photography is recommended to ensure best diagnosis possible for any further treatment options.

http://www.abc.net.au/rn/healthreport/stories/2010/2905728.htm

Diabetic Eye Disease

What is diabetes?

Diabetes is a chronic disease that prevents your body from making or using insulin, which in turn leads to increased sugar levels in your bloodstream, known as high blood sugar.

How does diabetes affect the eye?

Diabetes and its complications can affect many parts of the eye. Diabetes can cause changes in nearsightedness, farsightedness and premature presbyopia (the inability to focus on close objects). It can result in cataracts, glaucoma, paralysis of the nerves that control the eye muscles or pupil, and decreased corneal sensitivity.


What are visual symptoms of diabetes the eye?


Visual symptoms of diabetes include fluctuating or blurring of vision, occasional double vision, loss of visual field, and flashes and floaters within the eyes. Sometimes these early signs of diabetes are first detected in a thorough examination performed by a Doctor of Optometry.


Diabetic eye disease is a group of eye conditions that can affect people with diabetes and have the potential to cause severe vision loss and blindness.


1. Diabetic retinopathy affects blood vessels in the light-sensitive tissue called the        retina that lines the back of the eye. It is the most common cause of vision loss among people with diabetes and the leading cause of vision impairment and blindness among working-age adults.

2. Diabetic macular edema (DME). A consequence of diabetic retinopathy, DME is swelling in an area of the retina called the macula.

3. Cataract is a clouding of the eye’s lens. Adults with diabetes are 2-5 times more likely than those without diabetes to develop cataract. Cataract also tends to develop at an earlier age in people with diabetes.

4. Glaucoma is a group of diseases that damage the eye’s optic nerve—the bundle of nerve fibers that connects the eye to the brain. Some types of glaucoma are associated with elevated pressure inside the eye. In adults, diabetes nearly doubles the risk of glaucoma.

What is Diabetic Retinopathy?


Diabetic retinopathy occurs when there is a weakening or swelling of the tiny blood vessels in the retina of your eye, resulting in blood leakage, the growth of new blood vessels and other changes. If diabetic retinopathy is left untreated, blindness can result.

People with all types of diabetes (type 1, type 2, and gestational) are at risk for diabetic retinopathy. Risk increases the longer a person has diabetes. Between 40 and 45 percent of Americans diagnosed with diabetes have some stage of diabetic retinopathy, although only about half are aware of it. Women who develop or have diabetes during pregnancy may have rapid onset or worsening of diabetic retinopathy.


What is diabetic macular edema (DME)?

DME is the build-up of fluid (edema) in a region of the retina called the macula. The macula is important for the sharp, straight-ahead vision that is used for reading, recognizing faces, and driving. DME is the most common cause of vision loss among people with diabetic retinopathy. About half of all people with diabetic retinopathy will develop DME. Although it is more likely to occur as diabetic retinopathy worsens, DME can happen at any stage of the disease.

What are the symptoms of diabetic retinopathy and DME?


The early stages of diabetic retinopathy usually have no symptoms. The disease often progresses unnoticed until it affects vision. Bleeding from abnormal retinal blood vessels can cause the appearance of “floating” spots. These spots sometimes clear on their own. But without prompt treatment, bleeding often recurs, increasing the risk of permanent vision loss. If DME occurs, it can cause blurred vision.

The same scene as viewed by a person normal vision (Left) and with advanced diabetic retinopathy(Center). The floating spots are hemorrhages that require prompt treatment. DME causes blurred vision.

How are diabetic retinopathy and DME detected?

Diabetic retinopathy and DME are detected during a comprehensive dilated eye exam that includes:

1. Patient history to determine vision difficulties, presence of diabetes, and other general health concerns that may be affecting vision

2. Visual acuity testing. This eye chart test measures a person’s ability to see at various distances.Tonometry. This test measures pressure inside the eye.

3. Optical coherence tomography (OCT). This technique is similar to ultrasound but uses light waves instead of sound waves to capture images of tissues inside the body. OCT provides detailed images of tissues that can be penetrated by light, such as the eye.


4.
Pupil dilation. Drops placed on the eye’s surface dilate (widen) the pupil, allowing a physician to examine the retina and optic nerve. A comprehensive dilated eye exam allows the doctor to check the retina for:
        - Changes to blood vessels
        - Leaking blood vessels or warning signs of leaky blood vessels,
           such as fatty deposits
        - Swelling of the macula (DME)
        - Changes in the lens
        - Damage to nerve tissue

How is DME treated?

DME can be treated with several therapies that may be used alone or in combination.


1. Anti-VEGF Injection Therapy:
Anti-VEGF drugs are injected into the vitreous gel to block a protein called vascular endothelial growth factor (VEGF), which can stimulate abnormal blood vessels to grow and leak fluid. Blocking VEGF can reverse abnormal blood vessel growth and decrease fluid in the retina. Most people require monthly anti-VEGF injections for the first six months of treatment. Thereafter, injections are needed less often: typically three to four during the second six months of treatment, about four during the second year of treatment, two in the third year, one in the fourth year, and none in the fifth year. Dilated eye exams may be needed less often as the disease stabilizes.          

2. Focal/grid macular laser surgery:
In focal/grid macular laser surgery, a few to hundreds of small laser burns are made to leaking blood vessels in areas of edema near the center of the macula. Laser burns for DME slow the leakage of fluid, reducing swelling in the retina. The procedure is usually completed in one session, but some people may need more than one treatment. Focal/grid laser is sometimes applied before anti-VEGF injections, sometimes on the same day or a few days after an anti-VEGF injection, and sometimes only when DME fails to improve adequately after six months of anti-VEGF therapy.

3. Corticosteroids:
Corticosteroids, either injected or implanted into the eye, may be used alone or in combination with other drugs or laser surgery to treat DME. The Ozurdex (dexamethasone) implant is for short-term use, while the Iluvien (fluocinolone acetonide) implant is longer lasting. Both are biodegradable and release a sustained dose of corticosteroids to suppress DME. Corticosteroid use in the eye increases the risk of cataract and glaucoma. DME patients who use corticosteroids should be monitored for increased pressure in the eye and glaucoma.


How is proliferative diabetic retinopathy (PDR) treated?

For decades, PDR has been treated with scatter laser surgery, sometimes called panretinal laser surgery or panretinal photocoagulation. Treatment involves making 1,000 to 2,000 tiny laser burns in areas of the retina away from the macula. These laser burns are intended to cause abnormal blood vessels to shrink. Although treatment can be completed in one session, two or more sessions are sometimes required. While it can preserve central vision, scatter laser surgery may cause some loss of side (peripheral), color, and night vision. Scatter laser surgery works best before new, fragile blood vessels have started to bleed. Recent studies have shown that anti-VEGF treatment not only is effective for treating DME, but is also effective for slowing progression of diabetic retinopathy, including PDR, so anti-VEGF is increasingly used as a first-line treatment for PDR.


What if treatment doesn’t improve vision?

An eye care professional can help locate and make referrals to low vision and rehabilitation services and suggest devices that may help make the most of remaining vision. Many community organizations and agencies offer information about low vision counseling, training, and other special services for people with visual impairment. A nearby school of medicine or optometry also may provide low vision and rehabilitation services.


How can people with diabetes protect their vision?

Vision lost to diabetic retinopathy is sometimes irreversible. However, early detection and treatment can reduce the risk of blindness by 95 percent. Because diabetic retinopathy often lacks early symptoms, people with diabetes should get a comprehensive dilated eye exam at least once a year. People with diabetic retinopathy may need eye exams more frequently. Women with diabetes who become pregnant should have a comprehensive dilated eye exam as soon as possible. Additional exams during pregnancy may be needed.


Studies such as the Diabetes Control and Complications Trial (DCCT) have shown that controlling diabetes slows the onset and worsening of diabetic retinopathy. DCCT study participants who kept their blood glucose level as close to normal as possible were significantly less likely than those without optimal glucose control to develop diabetic retinopathy, as well as kidney and nerve diseases. Other trials have shown that controlling elevated blood pressure and cholesterol can reduce the risk of vision loss among people with diabetes.


Treatment for diabetic retinopathy is often delayed until it starts to progress to proliferative diabetic retinopathy (PDR), or when DME occurs. Comprehensive dilated eye exams are needed more frequently as diabetic retinopathy becomes more severe. People with severe nonproliferative diabetic retinopathy have a high risk of developing PDR and may need a comprehensive dilated eye exam as often as every 2 to 4 months.

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