One of the diabetes complications that may affect our eyes is diabetic retinopathy. This happens when high blood sugar levels cause damage to blood vessels in the retina. The retina detects light and converts it to signals sent through the optic nerve to the brain. Furthermore, it can cause blood vessels in the retina to leak fluid or hemorrhage (bleed), distorting vision.
In fact, diabetic retinopathy may cause no symptoms. As the condition progresses, the symptoms may include:
- Spots or dark strings floating in your vision (floaters)
- Blurred vision
- Fluctuating vision
- Impaired color vision
- Dark or empty areas in your vision
- Vision loss.
Consequently, diabetic retinopathy usually affects both eyes. However, it may progress through four stages:
Mild nonproliferative retinopathy
To start with, this is the earliest stage of the disease when small areas (microaneurysms) in the retina’s tiny blood vessels occur. Likewise, they may leak fluid into the retina
Moderate nonproliferative retinopathy
As the disease progresses, blood vessels that nourish the retina may swell and distort. Moreover, they may also lose their ability to transport blood.
Severe nonproliferative retinopathy
In this stage, not only many more blood vessels are blocked, but also the blood can’t be supplied to the areas of the retina. These areas secrete growth factors that signal the retina to grow new blood vessels.
Proliferative diabetic retinopathy (PDR)
At this advanced stage, the new blood vessels are fragile and they are more likely to leak and bleed as well. Accompanying scar tissue can contract and cause retinal detachment—the pulling away of the retina from underlying tissue and this can lead to permanent vision loss.
Source: https://nei.nih.gov/health/diabetic/retinopathy