DIABETES & EYE:
Diabetic Retinopathy
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Diabetic Retinopathy is an eye disease that destroys capillaries, the smallest blood vessels linking the arteries to veins.It does so by depostiing an abnormal material along the walls of the tiny blood cells in the retina. This condition is associated with the disease known a diabetic Mellitus. Blurred vision and often blindness follow. The longer a person has diabetes the greater his/her chances of developing diabetic retinopathy.
Eye Changes Associated With Diabetes
Changes in vision may happen at the time that diabetes is first diagnosed or at any time that blood sugar is high, it causes the lens to swell and shrink, and result in fluctuating vision. Many time, people who have "borderline" diabetes are unaware of their condition, until their vision becomes blurred. This is the reason why ophthalmologists are often the fist to detect diabetes.
This is due to the swelling of lens & /or corneal tissues secondary to elevated blood sugar levels. However, once insulin or other therapy has begun and the blood sugar drops the abnormal swelling diminishes. The vision may then fluctuate dramatically from day to day, and at different times of the day until blood sugar levels have stabilized.
Diabetic retinopathy damages the tiny blood vessels that supply the retina( the light sensitive nerve tissue at the back of the eye that transmits visual imagess to the brain). In the early stages of this disease called non-proliferaive or "background" retinopathy - the retinal vessels weaken and develop bulges (microaneursyms) that may leak blood (hemorrhages) or fluid ( exudate) into the surrounding tissue.
Proliferative diabetic retinopathy is characterised by the proliferation of newly formed blood vessels from the optic disc, retina or iris as the result of widespread retinal ischemia.
Background Diabetic Retinopathy (Non Proliferative)
Non- Proliferative background diabetic retinopathy or BDR is named appropriately because it sits in the bakground, not itself a danger of vision, but is instead a warning sign that serious damages may be starting. Non-proliferative diabetic retinopathy is characterized by abnormalities of the retinal circulation, including microaneurysms, intraretinal hamorrhages, cotton-wool spots, retinal edema and exudates, and intraretinal microvascular abnormalities.
Backgroound diabetic retinopathy consists of the following retinal changes.
1 Microaneurism
Scattered red blood cells in the retina where tiny, weakened blood cells have ballooned out.
2 Hemorrhages
Bleeding occurs from damaged blood vessels into the retinal layer.
3 Hard Exudates
caused by protiens & lipids from the blood leaking into the retina through damaged blood vessels.The presence of excess microalbimin in the urine identifies people who are 15 times as likely to go on to develop severe eye damage.
Another warning sign that the eyes are at risk for serious diabetic retinopthay is loss of dark adaptation. This loss is the ability to adapt to the dark is easiest to notice while visiting a movie theatre and have to wait in aisle while other people pass you by on their way to a seat.
Pre- proliferative Diabetic Retinaopathy
Pre- proliferative diabetic retinopathy is a more advanced stage of damage to the eye than the early signs found in BDR. Once this stage is present , vision can worsen rapidly if the progression of damage is not moniterd regulary and treated when it progresses to a certain stage. Changes to the eyes are documented with either retinal photographs or with a more precise fluorescein angiography test.
Changes Include:
1 Intra retinal Microvascular Abnormalities (IRMA)
these are irregular -shaped blood vessels that appera in a localised area of the retina as squiggly lines.
2 Cotton- Wool Spots
These are seen as pale white areas in the retina.
Proliferative Diabetis Retinopathy
Is a very advanced stage it can be seen in the eye with an ophthalmoscopeas neovascularization, a proliferative growth of abnormal new blood vessels.
They are very prone to bleeding, especially when they occur near the optic disc, the area where blood vessels and nerves enter the eye. Any jerking motion or even a rise in the blood pressure can lead to rupture of one of these abnormal vessels and casue hemorrhage. If excessive of repaeted bleeding occurs, fibrous tissue or scarring can form on the retina.
Macular Edema
The most common cause of visual loss in diabeties retinopathy is macular edema. It can occur if the swelling, leaking and hard exudates noted above in BDR occur within the macula, the central 5% of the retina most critical to vision.
Why does eye damage occur?
1 Leakage
High blood sugars cause damage to individual cells and later shows up as damage to structures like capillaries, the smallest of blood vessels.
Endothelial cells , which form a very smooth surface on the inner walls of blood vessels, and helper cells, called pericytes, are especially damaged by excess sugar.
As damage progresses the blood vessels walls atarts to become porous, letting protiens and other material leak out abnormally.
2 Blood Vessel Blockage
High sugars cause partial and total blockages within existing blood vessels.
Detection of Diabetic Retinopathy
A thorough eye examination will disclose the signs of diabetic retinopathy. In order to determine the extent of underlying retinal & vascular changes, your ophthalmologist may request that a retinal photography be performed prior to any laser treaatment procedure.
Treatment of Diabetic Retinopathy
Control od Daibetes does not necessarily insure you against development of daibetic retinopathy. Fortuunately both macular edema & peripheral retinopathy can be treated with laser surgery. And those with retinal detachment, prompt treatment with various surgical procedures can help to spare vision.
Regular Eye Exams Critical To Prevent Vision LOss
Keeping blood sugars normal is the best way to keep the eyes healthy. But to protect your vision , comprehensive eye exams are needed every year, or as directed by your physician. Remember, the most dangerous threats to vision in diabetes gives little or no warning. Only by direct examination with an ophthalmoscope can these early changes be seen and treatment started before sight becomes seriosly threatened.
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