EYES ON DIABETES

On 20 December 2006, the General Assembly of the United Nations passed a landmark Resolution recognising diabetes as a chronic, debilitating and costly disease. The Resolution designates World Diabetes Day as a United Nations Day to be observed every year.

The theme of World Diabetes Day 2016, on 14th November, is Eyes on Diabetes. Activities and materials will focus on promoting the importance of screening to ensure early diagnosis and treatment of type 2 diabetes, to reduce the risk of serious complications.

Diabetes is one of the fastest growing chronic diseases world-wide, and yet millions of people who have diabetes are unaware of it. While diabetes has the potential to cause severe vision problems, even people who may be aware of their diabetes do not always have an eye examination until they notice changes in their vision.By then it may be late, as some people already have undetected diabetic eye damage when their diabetes is diagnosed. Early detection leads to timely management of diabetic eye conditions, and may slow down the progress or even reverse the condition.

WHAT IS DIABETIC EYE DISEASE?

Diabetes is a chronic group of metabolic diseases in which the body cannot control the sugar levels in the blood. One of the effects of high blood sugar levels is a problem with the blood vessels, including the blood vessels in the eyes. Diabetic eye disease can affect the retina, macula, lens and the optic nerve. Damage to the retina is usually more serious than damage to the lens.

WHAT CAN GO WRONG WITH THE RETINA?

The retina at the back of the eye picks upwhat we see,and needs a good blood supply to keep it healthy and functioning effectively. With diabetes the blood vessels can become leaky, blocked or too small to let through enough blood, depriving the retina of oxygen and nutrients.

Damage to the retina through diabetes is called diabetic retinopathy. In its most advanced stage, new abnormal blood vessels increase in number on the surface of the retina, leading to scarring and cell loss.

Diabetic retinopathy is a process, and usually progresses through four stages, from mild nonproliferative retinopathy, through moderate and severe nonproliferative retinopathy, to proliferative diabetic retinopathy, which is the most serious but least common condition. The fact that it is a process implies that at any stage of its development retinopathy can be treated, and the disease progression can be slowed or even halted, preventing it from getting worse. The sooner it is diagnosed, the sooner treatment can begin.

WHAT CAN GO WRONG WITH THE MACULA?

The macula, which is a region on the retina, is important for the sharp, straight-ahead vision that is used for reading, recognising faces, and driving. Diabetic macula edema is the build-up of fluid in this area, gradually reducing vision. It is the most common cause of vision loss among people with diabetic retinopathy. Although it is more likely to occur as diabetic retinopathy worsens, diabetic macula edema can happen at any stage of the disease.

WHAT CAN GO WRONG WITH THE LENS?

A cataract is a clouding of the lens of the eye, blocking light from entering the eye. Many people without diabetes develop cataracts, but people with diabetes are twice as likely to develop this eye condition. People with diabetes also tend to get cataracts at a younger age and they often progress faster. Cataracts can usually be successfully treated.

WHAT CAN GO WRONG WITH THE OPTIC NERVE?

Diabetes is not the only cause of glaucoma, but people with diabetes are at greater risk of developing glaucoma than people who do not have diabetes. Glaucoma is an eye disease which damages the optic nerve, the bundle of nerve fibres that connects the eye to the brain. It occurs when pressure builds up in the eye, thus putting pressure on the blood vessels that carry blood to the retina and optic nerve, and reducing the amount of essential nutrients to these areas. This damages the retina and the nerve, and can cause gradual loss of vision. There are several treatments for glaucoma, including medication and surgery.

WHAT VISION CHANGES OCCUR IN DIABETIC RETINOPATHY?

The early stages of diabetic retinopathy usually have no symptoms, and the disease often progresses unnoticed until it affects vision. It is often referred to as the "silent thief of vision" for this reason. The changes in vision may include blurred vision, double vision, a feeling of pressure or pain in the eyes, seeing spots or "floaters, increased sensitivity to light, difficulty reading, or a loss of peripheral vision.

WHO IS AT RISK FOR DIABETIC RETINOPATHY?

Several factors influence whether you will develop retinopathy or not. These include blood glucose control, blood pressure levels, family history, and how long you have had diabetes.It is important to have a comprehensive eye examination when diabetes is diagnosed, and to discuss with your optometrist the risk of developing diabetic retinopathy. If necessary, treatment can be started immediately.Women who develop diabetes during pregnancy may have rapid onset of retinopathy, or, if they already have the condition, it may worsen during pregnancy.

HOW DOES MY OPTOMETRIST TEST FOR DIABETIC RETINOPATHY?

 As part of a comprehensive eye examination, the optometrist will examine the back of the eye, looking for signs of diabetic retinopathy, among other things. The pupils of the eyes may be dilated by means of eye drops, allowing a clear view of the retina and the optic nerve when a light is shone into the eye.

The eye examination may include:

• visual acuity testing, measuring the ability to see at various distances;
• tonometry, measuring the pressure inside the eye;
• ophthalmoscopy and slit lamp examination, allowingthe optometrist to see the structures within the eye, including the lens and the retina;
• optical coherence tomography (OCT) to check the condition of the retina;
• fundus photography, which produces detailed pictures of the back of the eye, and is valuable for tracking changes in the retina, by comparing photographs taken over a period of time.

Sometimes a fluorescein angiogram is needed to check for and locate leaking blood vessels in the retina. Fluorescent dye is injected into the bloodstream, and pictures of the retinal blood vessels are taken as the dye reaches the eye. This cannot be done by the optometrist, who will refer you to the appropriate specialist if necessary.

WHAT EXACTLY IS MY OPTOMETRIST LOOKING FOR?

Specifically, the optometrist is concerned about leaking blood vessels, changes to blood vessels, swelling of the macula, damage to the optic nerve, and changes in the lens.

HOW IS DIABETIC RETINOPATHY TREATED?

Vision lost to diabetic retinopathy is sometimes irreversible, but laser therapy can be done to seal new and leaking blood vessels, preventing or delaying further damage.Surgical treatment may be needed if bleeding from the retina into the eyeball is causing persistent cloudy vision or if scarring has occurred. Surgery is also available if the retina becomes detached from its base, which is sometimes a complication of proliferative retinopathy.

CAN DIABETIC EYE CONDITIONS BE PREVENTED?

 It may not be possible to prevent eye damage completely, but it is possible to reduce the risk of getting it and to stop it from getting worse if it is already evident. Early detection is the key! Monitor blood glucose levels, blood pressure and cholesterol by having regular check-ups. Smoking can exacerbate diabetes and its complications. As well as visiting your optometrist for regular eye examinations, report any vision changes immediately.