How Does Diabetes Affect Your Vision?
Diabetes is a disorder that prevents you from properly using and storing the sugars broken down from the food you eat. Having high levels of blood sugars can damage your blood vessels, especially those in your retina – the nerve layer that detects light and allows you to see. Diabetic retinopathy is the term used to describe having damaged retinal vessels. Damaged blood vessels can lead to bleeding and swelling in the back of your eye, which can eventually lead to a loss in vision.
Types Of Diabetic Retinopathy
Diabetic retinopathy can be one of two types: non-proliferative and proliferative diabetic retinopathy.
Non-Proliferative Diabetic Retinopathy (NPDR)
NPDR is an early stage of diabetic retinopathy. It is characterized by the blood vessels in the retina leaking, causing the retina to swell with fluid and accumulate yellow fatty deposits known as exudates. Mild forms of NPDR usually do not affect vision, unless the swelling occurs near the macula – the small specialized area in the back of your eye that allows you to see fine detail. This is called macular edema, and visual loss may be mild to severe, while peripheral vision remains intact. In some cases, the vessels may close off such that the macula cannot receive oxygen or nutrients. This is call macular ischemia, and also causes visual loss.
Proliferative Diabetic Retinopathy (PDR)
PDR occurs when the retinal vessels are damaged to the point where they become blocked off and the retina isn’t receiving adequate bloodflow. In an attempt to make up for the loss of nutrients and oxygen, the retina responds by forming new vessels. However, these new vessels are weak and leaky, eventually forming scar tissue that can cause the retina to be detached. PDR can cause rapid and severe vision loss, affecting both the central and peripheral vision. Vision can be affected in numerous ways:
- Vitreous Hemorrhage – the new vessels formed are fragile and can bleed into the vitreous, the main gel-like cavity of your eye. You may experience dark “floaters” in your vision, or even a complete loss. Usually the blood is reabsorbed within days or months, but if not, a vitrectomy surgery can be performed to rid the cavity of the blood. Once the blood has cleared, vision will be normal again, unless the macula is damaged.
- Tractional Retinal Detachment – when new blood vessels develop in PDR they eventually form scar tissue, which shrinks and pulls on the thin retina nerve layer. If this wrinkling occurs at the macula, vision can be distorted. In some severe cases, it can actually pull the retina right off.
- Neovascular Glaucoma – in some cases, new vessels will also grow onto the iris – the colored part of your eye. Having new vessels form here can block the drainage passages of your eye and fluid can build up, leading to an increased intraocular pressure. This eventually results in neovascular glaucoma, a disease that damages your optic nerve and vision.
A medical eye exam is necessary in order to detect any changes inside your eye caused by having diabetes. To do this, your ophthalmologist will dilate your pupils to look at the back of your eyes with special lenses. It’s important to get regular check-ups because diabetic retinopathy can be detected and treated before you have any visual loss. The earlier the detection, the more likely you are to preserve your vision.
How Often Should You Have Your Eyes Examined?
People with diabetes under the age of 29 should have their eyes examined within the first 5 years of diagnosis, and every year after that. People over the age of 30 should have them examined as soon as possible. If you’re pregnant and have diabetes, an appointment should be made within the first trimester, because diabetic retinopathy can progress rapidly.
Rapid changes in blood sugar can cause fluctuating vision in both eyes, regardless if diabetic retinopathy is present. Any visual changes that last more than a few days and aren’t associated with a change in blood sugar, should be examined immediately.
In order to prevent any visual loss, it’s important to detect and treat any diabetic retinopathy at an early stage. To help reduce the risk, strict control of your blood sugar and treating any blood pressure or kidney problems can help. Once diabetic retinopathy has developed, there a number of ways it can be treated:
- Medical Treatment – To stop the growth of new vessels forming on your retina, your ophthalmologist can inject an anti-VEGF medication into your eye. This chemical targets and stops the VEGF growth factor that promotes the new vessel formation. Sometimes a steroid medication is also used.
- Laser Surgery – Laser surgery involves a focused beam of light used in people with macular edema or PDR. In Macular edema, the laser is used to decrease the fluid leaked in your macula, to prevent any further vision loss. The laser targets just the macular area. In PDR, the laser is focused in many small spots spanning the retina to destroy all the newly formed vessels. This is termed panretinal photocoagulation, which causes the vessels to shrink and prevents more from forming. In doing so, the risk of vitreous hemorrhage or retinal distortion is decreased.
- Vitrectomy – In severe cases of PDR, blood may leak into the vitreous cavity of your eye. If it doesn’t clear on it’s own in a couple months, your ophthalmologist may recommend a vitrectomy, in which he or she surgically removes the gel-like vitreous and replaces it with a clear solution. This is done in an operating room. Not only does this procedure clear away the unwanted blood blocking your vision, but it often prevents further bleeding by removing the abnormal vessels. Any retinal detachments can also be repaired during this procedure if needed. It is important for surgery to be done as early as possible, because visual loss can be permanent if the macula is distorted or the retina is detached for too long.