Diabetic Eye Health, Complications, & Care
Diabetes can cause many problems if not properly controlled, including damage to the heart, kidneys, blood vessels, and eyes. High blood sugar levels can damage the eye’s blood vessels when they consistently occur over time.
The body uses glucose for cell energy and processes. Consumed sugar ends up as glucose in the bloodstream. When the pancreas works normally, it notices the uptick in blood sugar and sends the hormone insulin to escort the sugar into the cells.
This puts the sugar into the cells where it’s needed and reduces the blood sugar level to normal limits. Someone without diabetes will generally have a blood sugar level of less than 140mg/dL within two hours of their last meal.
Someone with diabetes may have extremely high blood sugar levels, upwards of 300mg/dL to 400mg/dL or more, and not necessarily even know it. Diabetes will occasionally cause symptoms, such as thirst, weakness, dizziness, hunger, and excessive urination, but some people may never experience any symptoms.
The term dL refers to a deciliter, or roughly one-tenth of a liter (about a quart) of blood.
You can definitely have diabetes or a prediabetic condition and not even know it. The risk of both diabetes itself and its possible eye complications rises with age. For this reason, both the Academy of Ophthalmology and the American Diabetes Association recommend annual eye exams for everyone over the age of 65.
Rishi Singh, MD, a Cleveland Clinic Cole Eye Institute physician, also recommends annual eye exams for anyone with a significant family history of diabetes. The disease can run in families, and your personal risk may be higher if you have a biological parent or sibling with diabetes.
The overall occurrence of diabetes has risen sharply in recent decades. Type 2 diabetes, also called adult-onset diabetes, affects more than 30 million Americans. This includes one-fourth of those over the age of 65. Out of all of these people, a full one-quarter have no idea that they’re diabetic or that they’re at risk for eye complications.
The other primary type of the disease, Type 1, sometimes called juvenile diabetes, typically affects children, although anyone can get it. It has a different cause than Type 2, but the other aspects of the disease are the same, including the risk of vision damage and loss.
How Does Diabetes Harm Eyesight?
At first glance, it may seem like blood sugar and eye damage have nothing to do with each other, but this isn’t true. Again, looking at the function of insulin to normalize blood sugar levels and keep them as low as they should be, we can see why uncontrolled diabetes may damage the body’s organs.
Problems arise when there is too much sugar in the bloodstream. Excess glucose damages tiny blood vessels and impedes blood flow, resulting in not enough oxygen and nutrients reaching the target tissues served by these tiny blood vessels.
These damaged blood vessels then leak, swell, and function improperly. Blood vessel leaks can damage the eye’s lens, causing cataracts. These leaks can also damage the retina located at the back of the eye, where the images we see are formed and transmitted to the brain.
Diabetes damage can cause retinal blood vessels to bleed. Excess fluid called edema can also harm the retina and impair function. This can seriously damage the eye, resulting in a loss of vision if not caught in time. Diabetic eye complications can ultimately lead to blindness.
Diabetic Eye Disease
The statistics are sobering: Someone with uncontrolled or poorly controlled diabetes has a 90 percent chance of significant retinal damage after 20 years. This is called diabetic retinopathy, literally meaning diabetic retinal damage, and it’s the fourth leading cause of blindness in the world.
We can expect this figure to increase as the occurrence of diabetes also increases. The retinal bleeding and possible retinal detachment caused by the bleeding must be corrected by surgery, but this is not always successful. Vision loss may still be permanent.
The macula is the very center of the retina where the sharpest, clearest central vision is formed. When the retina swells from diabetes, it’s called diabetic macular edema, and it’s the second leading cause of diabetic vision loss. Macular edema is a direct result of excessively high blood sugar levels and can occur at any stage of diabetes.
Diabetes also increases the risk of glaucoma, a disease where high-pressure levels within the eye gradually damage the optic nerve. As you may imagine, this can also cause blindness if not treated in time.
Diabetic Eye Exams
Of course, the main focus of diabetic treatment is to control blood sugar levels with medication, diet, exercise, or insulin. However, diabetic eye exams are also important because most diabetics have no warning eye symptoms, or if they do, they dismiss them without realizing how serious they may be.
Blurry, wavy vision, or patches of missing vision are dire warning signs that may be ignored by a diabetic that is unaware of the condition.
Diabetic eye exams should involve dilating the pupil with drops that allow the doctor to obtain a clear view of the retina to check it for damage. A cursory eye exam, such as that to determine the need for corrective lenses, is not sufficient.
Treatment of Diabetic Eye Disease
If caught in the early stages, some types of mild and intermediate diabetic eye diseases may be treatable with laser therapy and certain injectable biologic medications that fight retinal swelling and neovascularization, a medical term referring to the abnormal growth of blood vessels.
These blood vessels are a problem because they are considered to be abnormal and are not supposed to be there. Weakened blood vessels are prone to damage and bleeding, which can cause further damage, inflammation, and irritation to the area.
Various biological medications are injected directly into the eye and improve vision about one-third of the time. They are more effective in reducing the growth of abnormal blood vessels. They will stabilize the growth of these problematic blood vessels about 90 percent of the time.
A medical test called an A1C, a simple blood test, is an important diagnostic tool. It measures how stable your blood glucose levels are over time by measuring the amount of glucose attached to the hemoglobin in your cells. The A1C test will give your doctor a relatively accurate picture of your blood glucose levels over the last 90 days or so.
Diabetes and Your Health
Diabetes is one of the leading causes of kidney disease serious enough to require dialysis. It can cause neuropathy, a painful tingling of the hands and feet. Because it damages blood vessels all over the body, diabetes can lead to amputations of the feet and hands when their tissues die from lack of oxygen.
Diabetes is treated by primary care doctors and endocrinologists specializing in glandular and metabolic disorders.
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