Can Diabetes Lead to Blindness?

By Samantha Semoso – EMTV Online

Diabetics are believed to be at a higher risk of contracting eye-related issues, new research has shown.

High blood sugar levels thanks to diabetes can lead to damage of the retina, the layer on the back of the eye that captures images and sends them as nerve signals to the brain.

Whether diabetic retinopathy develops depends in part on how high blood sugar levels have been, and for how long they may have been above the ideal range. 

The early stages of retinal damage is called nonproliferative retinopathy. First, tiny blood vessels called capillaries in the retina develop weakened areas in their walls called micro aneurysms. When red blood cells escape through these weakened walls, tiny amounts of bleeding (haemorrhages) become visible when the retina is viewed through an instrument called an ophthalmoscope. To clearly see your retina, the ophthalmologist will enlarge (dilate) your pupils (which serve as a window to the back of your eye) and may also use a special dye to help identify blood vessels that may be leaking.

Fluid from the blood also escapes, leading to yellowish hard exudates. This type of damage does not cause problems with vision unless some of the leaking fluid is near the macula.

An ophthalmologist who specialises in the treatment of the retinal problems will attempt to stop blood leakage by using laser in a process called photocoagulation. By using an appropriately selected laser, the ophthalmologist will seal the small blood vessels that can leak when a person has no proliferative retinopathy. 

If fluid leaks out near the macula, it can disrupt vision. This is called macular edema. As retinopathy becomes more severe, parts of the abnormal capillaries can become closed off. This kills part of the retina that the capillaries previously supplied with blood. T

The late stages of retinal injury are called proliferative retinopathy, with new fragile blood vessels grown to supply the damaged arears of the retina. These new blood vessels can bleed into the vitreous gel, the gel-filled area in front of the retina. 

Severe proliferative retinopathy may be treated with laser surgery in order to save vision. Your eye doctor may use aggressive laser therapy, called scatter (pan-retinal) photocoagulation. This process is more thorough than that used in localised photocoagulation.

Severe proliferative retinopathy may also be treated with medicines that slow the growth of abnormal blood vessels in the retina. The growth of these vessels is triggered by a protein called Vascular Endothelial Growth Factor (VEGF). Anti-VEGF medicines, such as ranibizumab (Lucentis), block the effects of VEGF.

Laser treatments may not always work in treating proliferative retinopathy. If you have retinal detachment or haemorrhages that cannot be repaired, your retinal specialist will use a surgical technique to try and restore vision. 

People who have diabetes are also at a greater risk for problems such as cataracts and glaucoma. They are also at risk for a severe form of glaucoma called neovascular glaucoma.

Cataracts are frequently caused by a lifetime of sun exposure, and diabetes speeds up their formation.