For those who are living with diabetes, you know that this is a life-changing diagnosis. Diabetes affects over 38 million Americans, but a significant proportion of these are undiagnosed. The consequences of diabetes go beyond just restricting what you put on your plate – among other things, poorly managed diabetes can affect your feet, heart, kidneys, mental health and, not to mention, your eyes.
What is diabetes?
Diabetes is a chronic disorder involving a hormone called insulin. Insulin’s job is to allow the cells of the body to take up glucose (sugar) from the bloodstream once it has been digested from your food and drink. In diabetes, your body’s pancreas either doesn’t produce enough (or any) insulin or your body isn’t able to use the insulin effectively. This means glucose digested from your food doesn’t make it into your cells and instead continues to circulate around your body in your blood. Far from being a sweet deal, the high blood sugar levels can cause all sorts of problems.
Having diabetes increases your risk of:
- Cardiovascular diseases, such as stroke
- Chronic kidney disease
- Nerve damage (neuropathy)
- Foot problems from nerve damage and poor blood circulation
- Gum disease
- Hearing loss
- Blindness and vision impairment
How does diabetes affect the eyes?
The elevated blood glucose levels associated with diabetes causes damage to the walls of the blood vessels. This is why the complications of diabetes are so widespread, literally from your toes up to your eyeballs.
A diabetic eye test can determine a number of eye-related complications:
- Diabetic retinopathy: the tiny blood vessels through the retina (the light-sensitive tissue at the back of your eye) become leaky due to high blood glucose levels. This results in bleeding and fluid leakage from the vessels, which leads to swelling, scarring, and poor oxygen supply. The low oxygen may trigger the growth of new blood vessels to compensate, but these vessels are poorly formed, causing more bleeding and fluid leakage. Depending on the extent and location of any bleeding, you may notice blurry or missing parts of your vision.
- Diabetic macular edema: the macula is the part of the retina involved in fine detail central vision. Fluid leakage under the macula causes swelling and distortion or loss of vision.
- Glaucoma: glaucoma is a complicated eye disease that can be related to a number of causes and other conditions. It results in progressive vision loss due to damage of the optic nerve. Diabetes doubles the risk of glaucoma. The new blood vessel growth described above in diabetic retinopathy can also develop in the drainage channels of the eye. This blocks fluid (specifically, aqueous humor) from draining, increasing the pressure inside in the eye, and causing damage to the optic nerve.
- Cataracts: clouding of the eye lens
What is involved in a diabetic eye test?
In addition to the components of a regular eye test (because people with diabetes wear glasses, too), a diabetic eye test always includes a dilated eye exam. This involves having eye drops that widen your pupil, the opening in the center of your colored iris. The pupil plays an important role by constricting in response to light. But when your eye doctor is trying to look through your pupil to examine your retina, this is not helpful. The dilating eye drops open up your pupils so that your doctor can get a better view of the retina, looking for any signs of retinopathy, diabetic macular edema, or glaucoma.
Other tests that often accompany a diabetic eye examination include:
- Measuring eye pressure: this relates to your risk of glaucoma
- Visual field testing: a test of your peripheral vision, particularly if there is suspicion of glaucoma
- Visual acuity testing: to record how well your macula is working and monitor the effects of any diabetic eye disease
- Optical coherence tomography (OCT): this imaging technique can give additional detail about different structures in the eye, including your macula and optic nerves
- Retinal photography: not technically a test, a retinal photo is exactly as it sounds – a photo of your retina. This doesn’t necessarily provide any further details that can’t be seen behind the slit lamp microscope, but does help to record changes over time
How often should I have a diabetic eye test?
The current recommendations for the frequency of diabetic eye tests are:
- Every year within 5 years of being diagnosed with type 1 diabetes
- Every year from the time you’re diagnosed with type 2 diabetes
Type 1 diabetes is an autoimmune condition where the body attacks the insulin-producing cells in the pancreas. It usually develops in childhood or adolescence, and people with Type 1 must take insulin for life.
Type 2 diabetes is more common, often develops in adults, and is linked to lifestyle factors. In Type 2, the body becomes resistant to insulin or doesn’t produce enough. It can sometimes be managed with diet, exercise, and oral medications.
However, your eye doctor may want to review you more often if you have evidence of diabetic eye disease already, or if you have additional risk factors for developing problems. High cholesterol, high blood pressure, and smoking make you more likely to get diabetic eye disease and more severely. African Americans and Latinos are also at a higher risk compared to Caucasians.
If caught promptly, there are sight-saving treatments available for diabetic eye disease. The keyword here is promptly. So, if you have diabetes and are a little overdue for your annual eye test, let this be your sign!