Diabetic retinopathy — vision-threatening damage to the retina of the eye caused by diabetes — is the leading cause of blindness among working-age population (20-65 years).
The good news: Diabetic retinopathy often can be prevented with early detection, proper management of your diabetes and routine eye exams performed by your ophthalmologist.
According to the International Agency for Prevention of Blindness (IAPB), 75% of Diabetics live in middle to low income countries like South Africa. Roughly 10 percent of the SA population between the ages of 20 and 79 have the disease.
About 90 percent of South Africans with diabetes have type 2 diabetes, which develops when the the body becomes insensitive to insulin — a hormone secreted by the pancreas that enables dietary sugar to enter the cells of the body — or the body becomes resistant to insulin. This causes glucose (sugar) levels in the bloodstream to rise and can eventually damage the eyes, kidneys, nerves or heart.
Risk factors for type 2 diabetes include obesity, an unhealthful diet and physical inactivity. Unfortunately, the prevalence of obesity and type 2 diabetes has increased significantly in South Africa for the past 25 years. The prevalence of Diabetes has gone up by 25% in the last 25 years.
Between 4,000 and 8,000 new cases of blindness from diabetic retinopathy occur in South Africa yearly, many could be prevented with early intervention. But 50% of diabetics never come for their yearly ophthalmic consults. They simply do not recognize their risk for vision loss.
Generally, diabetics don’t develop diabetic retinopathy until they have had diabetes for at least 10 years. But it is unwise to wait that long for an eye exam.
With any diagnosis of diabetes, your primary care physician should refer you to an eye doctor (ophthalmologist) for a diabetic eye exam at least once a year.
HOW DOES DIABETES CAUSE DIABETIC RETINOPATHY?
Diabetes mellitus (DM) causes abnormal changes in the blood sugar (glucose) that your body ordinarily converts into energy to fuel different bodily functions.
Uncontrolled diabetes allows unusually high levels of blood sugar (hyperglycemia) to accumulate in blood vessels, causing damage that hampers or alters blood flow to your body’s organs — including your eyes.
Diabetes generally is classified as two types:
- Type 1 diabetes. Insulin is a natural hormone that helps regulate the levels of blood sugar needed to help “feed” your body. When you are diagnosed with type 1 diabetes, you are considered insulin-dependent because you will need injections or other medications to supply the insulin your body is unable to produce on its own. When you don’t produce enough of your own insulin, your blood sugar is unregulated and levels are too high.
- Type 2 diabetes. When you are diagnosed with type 2 diabetes, you generally are considered non-insulin-dependent or insulin-resistant. With this type of diabetes, you produce enough insulin but your body is unable to make proper use of it. Your body then compensates by producing even more insulin, which can cause an accompanying abnormal increase in blood sugar levels.
With both types of diabetes, abnormal spikes in blood sugar increase your risk of diabetic retinopathy.
Eye damage occurs when chronically high amounts of blood sugar begin to clog or damage blood vessels within the eye’s retina, which contains light-sensitive cells (photoreceptors) necessary for good vision.
SYMPTOMS OF DIABETIC RETINOPATHY AND OTHER DIABETES-RELATED EYE PROBLEMS
You first may notice diabetic retinopathy (DR) or other eye problems related to diabetes when you have symptoms such as:
- Fluctuating vision
- Eye floaters and spots
- Development of a scotoma or shadow in your field of view
- Blurry and/or distorted vision
- Corneal abnormalities such as slow healing of wounds due to corneal abrasions
- Double vision
- Eye pain
- Near vision problems unrelated to presbyopia
During an eye examination, your eye doctor will look for other signs of diabetic retinopathy and diabetic eye disease. Signs of eye damage found in the retina can include swelling, deposits and evidence of bleeding or leakage of fluids from blood vessels.
Your eye doctor will use a special camera or other imaging device to photograph the retina and look for telltale signs of diabetes-related damage.
For a definitive diagnosis, you may need to undergo a test called a OCT angiography. This test only takes a minute or two to do. No dilation of your eyes, no injections, no yellow dyes, no risk of allergic reactions.
One sometimes overlooked symptom of diabetic eye disease is nerve damage (neuropathy) affecting ocular muscles that control eye movements. Symptoms can include involuntary eye movement (nystagmus) and double vision.
TYPES OF DIABETIC EYE DISEASE
Once high blood sugar damages blood vessels in the retina, they can leak fluid or bleed. This causes the retina to swell and form deposits in early stages of diabetic retinopathy.
In later stages, leakage from blood vessels into the eye’s clear, jelly-like vitreous can cause serious vision problems and eventually lead to blindness.
Clinically significant macular edema (CSME).
This swelling of the macula more commonly is associated with type 2 diabetes. Macular edema may cause reduced or distorted vision.
Diabetic macular edema (DME) typically is classified in two ways:
- Focal, caused by microaneurysms or other vascular abnormalities sometimes accompanied by leaky blood vessels.
- Diffuse, which describes dilated or swollen tiny blood vessels (capillaries) within the retina.
If you have CSME, you typically are advised to undergo intraocular anti VEGF injections.
Non-proliferative diabetic retinopathy (NPDR).
This early stage of DR — identified by deposits forming in the retina — can occur at any time after the onset of diabetes.
Often no visual symptoms are present, but examination of the retina can reveal tiny dot and blot hemorrhages known as microaneurysms, which are a type of out-pouching of tiny blood vessels.
In type 1 diabetes, these early symptoms rarely are present earlier than three to four years after diagnosis. In type 2 diabetes, NPDR can be present even upon diagnosis.
Proliferative diabetic retinopathy (PDR).
Of the diabetic eye diseases, proliferative diabetic retinopathy has the greatest risk of visual loss.
The condition is characterized by these signs:
- Development of abnormal blood vessels (neovascularization) on or adjacent to the optic nerve and vitreous.
- Pre-retinal hemorrhage, which occurs in the vitreous humor or front of the retina.
- Ischemia from decreased or blocked blood flow, with accompanying lack of oxygen needed for a healthy retina.
These abnormal blood vessels formed from neovascularization tend to break and bleed into the vitreous humor of the eye. Besides sudden vision loss, more permanent complications can include tractional retinal detachment and neovascular glaucoma.
Macular edema may occur separately from or in addition to NPDR or PDR.
You should be monitored regularly, but you typically don’t require antiVEGF for diabetic eye disease until the condition is advanced.
WHO GETS DIABETIC RETINOPATHY?
Beyond the presence of diabetes, how well your blood sugar is controlled is a major factor determining how likely you are to develop diabetic retinopathy with accompanying vision loss.
Uncontrolled high blood pressure (hypertension) has been associated with eye damage related to diabetes. Also, studies have shown a greater rate of progression of diabetic retinopathy in diabetic women when they become pregnant.
Of course, the longer you have diabetes the more likely you are to have vision loss.
The American Academy of Ophthalmology (AAO) notes that all diabetics who have the disease long enough eventually will develop at least some degree of diabetic retinopathy, though less advanced forms of the eye disease may not lead to vision loss.
HOW IS DIABETIC RETINOPATHY DIAGNOSED?
A complete eye examination is required for the detection of diabetic retinopathy. If there is evidence of diabetic retinopathy other special investigations will be done to assess the stage of the diabetic retinopathy. These include an OCT examination which scans the different layers of the retina allowing early detection of diabetic related retinal involvement. A fluroscein angiogram may be indicated if there is fluid and blood on the macula area.
HOW IS DIABETIC RETINOPATHY TREATED?
In early cases only regular follow-up may be necessary. More advanced cases require treatment to control the damage of diabetic retinopathy and improve sight. Laser photocoagulation involves the focusing of a powerful beam of laser light on the damaged retina to seal leaking retinal blood vessels and stop abnormal blood vessel [neovascularization] growth.
Vitrectomy – In the event of the patient presenting with very advanced diabetic retinopathy, a microsurgical procedure known as vitrectomy is recommended. Blood-filled vitreous gel of the eye is replaced with a clear solution to aid in restoring vision. Sometimes the retina may also be detached. Vitrectomy surgery is then performed to reattach the retina.
HOW TO PREVENT VISUAL LOSS IN DIABETES?
Prevention of diabetic retinopathy and accompanying visual loss is a team effort involving the patient and our team of diabetic eye specialists. Early detection of diabetic retinopathy is the best protection against loss of vision. Diabetics must have their retinas examined at least once a year. Diabetics should be managed by endocrinologists or physicians passionate about diabetes.