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Overview
Diabetes is a disease that occurs when the pancreas does not secrete enough insulin or the body is unable to process it properly. Insulin is the hormone that regulates the level of sugar (glucose) in the blood. Diabetes can affect children and adults.
How does diabetes affect the retina?
Patients with diabetes are more likely to develop eye problems such as cataracts and glaucoma , but the disease’s affect on the retina is the main threat to vision. Most patients develop diabetic changes in the retina after approximately 20 years. The effect of diabetes on the eye is called diabetic retinopathy.
Over time, diabetes affects the circulatory system of the retina. The earliest phase of the disease is known as background diabetic retinopathy. In this phase, the arteries in the retina become weakened and leak, forming small, dot-like haemorrhages. These leaking vessels often lead to swelling or edema in the retina and decreased vision.
The next stage is known as proliferative diabetic retinopathy. In this stage, circulation problems cause areas of the retina to become oxygen-deprived or ischemic. New, fragile, vessels develop as the circulatory system attempts to maintain adequate oxygen levels within the retina. This is called neovascularization. Unfortunately, these delicate vessels hemorrhage easily. Blood may leak into the retina and vitreous, causing spots or floaters , along with decreased vision.
In the later phases of the disease, continued abnormal vessel growth and scar tissue may cause serious problems such as retinal detachment and glaucoma.
Variations in vision are caused by changes in the sugar content of the lens of the eye or the blood sugar level changes. All increase in blood sugar thus tends to make a person relatively more short sighted and a decrease relatively more long sighted.
Episodes of uncontrolled blood sugar can cause cataracts in young patients. Diabetes also causes the usual old age problems to occur at a younger age and more frequently.
Diabetes most importantly causes retinopathy. Normally the blood vessels in the retina do not leak. But with diabetes, the retinal blood vessels can develop tiny leaks which causes fluid of blood to seep into the retina. The retina then becomes wet and swollen and cannot work properly. The effect on vision is especially grave when this swelling involves the macula. Diabetes also causes the retinal blood vessels to close resulting in malfunction and death of those parts of the retina supplied by these blood vessels. The areas of the retina in which blood vessels have closed then foster the growth of abnormal new blood vessels called neovascularization. Neovascularization causes bleeding and scar tissue that can result in vitreous haemorrhage, retinal detachment and blindness.
Signs and Symptoms
The affect of diabetic retinopathy on vision varies widely, depending on the stage of the disease. Some common symptoms of diabetic retinopathy are listed below, however, diabetes may cause other eye symptoms.
- Blurred vision (this is often linked to blood sugar levels
- Floaters and flashes
- Sudden loss of vision
Detection and Diagnosis
Diabetic patients require routine eye examinations so related eye problems can be detected and treated as early as possible. Most diabetic patients are frequently examined by an internist or endocrinologist who in turn work closely with the ophthalmologist.
The diagnosis of diabetic retinopathy is made following a detailed examination of the retina with an ophthalmoscope . Most patients with diabetic retinopathy are referred to vitreo-retinal surgeons who specialize in treating this disease.
Treatment
Diabetic retinopathy is treated in many ways depending on the stage of the disease and the specific problem that requires attention. The retinal surgeon relies on several tests to monitor the progression of the disease and to make decisions for the appropriate treatment. These include: fluorescein angiography , retinal photography , and ultrasound imaging of the eye.
The abnormal growth of tiny blood vessels and the associated complication of bleeding is one of the most common problems treated by vitreo-retinal surgeons. Laser surgery called pan retinal photocoagulation (PRP) is usually the treatment of choice for this problem.
With PRP, the surgeon uses laser to destroy oxygen-deprived retinal tissue outside of the patient’s central vision. While this creates blind spots in the peripheral vision, PRP prevents the continued growth of the fragile vessels and seals the leaking ones. The goal of the treatment is to arrest the progression of the disease.
Vitrectomy is another surgery commonly needed for diabetic patients who suffer a vitreous hemorrhage (bleeding in the gel-like substance that fills the center of the eye). During a vitrectomy, the retina surgeon carefully removes blood and vitreous from the eye, and replaces it with clear salt solution (saline). At the same time, the surgeon may also gently cut strands of vitreous attached to the retina that create traction and could lead to retinal detachment or tears.
Patients with diabetes are at greater risk of developing retinal tears and detachment. Tears are often sealed with laser surgery. Retinal detachment requires surgical treatment to reattach the retina to the back of the eye. The prognosis for visual recovery is dependent on the severity of the detachment.
Prevention
Researchers have found that diabetic patients who are able to maintain appropriate blood sugar levels have fewer eye problems than those with poor control. Diet and exercise play important roles in the overall health of those with diabetes.
Diabetics can also greatly reduce the possibilities of eye complications by scheduling routine examinations with an ophthalmologist. Many problems can be treated with much greater success when caught early.
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What is diabetic eye disease?
Diabetic eye disease refers to a group of sight-threatening eye problems that people with diabetes may develop as a complication of the disease. They include:
Diabetic retinopathy
This disease damages blood vessels in the retina, the light-sensitive tissue at the back of the eye that translates light into electrical impulses that the brain interprets as vision. The tiny blood vessels in the retina weaken or swell, causing blood leakage, new vessel formation and other changes that damage the nerve cells which transmit images to the brain. In the early stage, traces of blood and fat deposit will appear on the retina, but the patient's vision will be normal.
Cataract
A cataract is an opacity of the eye's crystalline lens that results in blurring of normal vision. People with diabetes are twice as likely to develop a cataract as someone who does not have the disease. In addition, cataracts tend to develop at an earlier age in people with diabetes, around late middle age.
Glaucoma
This disease occurs when increased fluid pressure in the eye leads to progressive optic nerve damage. People with diabetes are nearly twice as likely to develop glaucoma as other adults.
What are the symptoms of diabetic retinopathy?
For many people with diabetic retinopathy, there are no early symptoms. There is no pain, no blurred vision, and no ocular inflammation. In fact, many people do not develop any visual impairment until the disease has advanced well into its proliferative stage. At this point, the vision that has been lost cannot be restored.
However, some people in the early and advanced stages of diabetic retinopathy may notice a change in their central and/or colour vision. The loss of central vision results from macular edema, which can often be effectively treated.
How is diabetic eye disease detected?
Because diabetic eye disease often has no early symptoms, it is often detected during a comprehensive eye examination.
