Long-term diabetes or unregulated blood sugar levels can damage the fine, capillary-rich retinal layer at the back of the eye. The retina is full of rods and cones, light-sensitive cells that convert light into electric signals that are transmitted to the brain. This layer is nourished by a mesh network of blood vessels. 

In patients with diabetic retinopathy, these fine blood vessels begin to leak and rupture blood onto the retina. In its advanced stage, new and irregular blood vessels start to grow and bleed into the eye. DR may present as floaters in the eye, and lead to decreased or fluctuating vision.

The central retina is especially rich with light-sensitive cells and is called the macula, and its very centre is the fovea. We use the fovea for detailed and crisp vision, such as for readings these words. Chronic diabetes can lead to a buildup of leaked fluids, blood and protein deposits behind the macula, inflaming and thickening it, and ultimately, damaging vision.

DME and DR are tightly linked, though not all people with DR may develop DME. The difference may include the location of the capillary hemorrhage (central or peripheral retina). 

• Non-proliferative diabetic retinopathy (NPDR)
  Abnormal bleeding of blood vessels reduces blood flow to parts of the retina. This leads to ‘ischemia’ or inadequate supply of blood, and therefore oxygen, to these parts. NPDR is further classified into mild, moderate and severe stages. 
• Proliferative diabetic retinopathy (PDR)
  At this stage, abnormal new blood vessels start forming across the retina. However, they are mal-formed and disintegrate, leaking blood into the central chamber of the eye. PDR may also result in scars that result in a retinal detachment and vision loss.

DR has no visible symptoms in the early stages of the disease. The risk factors to look out for are unregulated blood sugars or chronic hypertension. People with diabetes should look out for the following signs:

• Floaters in their vision
• Blurred or diminishing vision
• Poor night vision
• Spots or blank regions in the visual field

People living with long-term diabetes, with high HBA1C scores, or those with hypertension are at risk. Regular, comprehensive eye examinations will help identify DR onset.

Bringing blood sugars and blood pressure under control is the critical first step towards managing diabetic retinopathy. 

• Anti-VEGF medication: Anti-vascular endothelial growth factor drugs can reduce the inflammation, especially in the macula. These are delivered as injections deep into the eye by trained retinal specialists.
• Laser Therapy: Lasers are used to ‘cauterise’ some of the abnormal blood vessels and stopping them from leaking blood. This approach may also reduce the release of VEGF thereby stalling the progression of damage.
• Surgery: In severe cases, retinal specialists may opt for surgical interventions to remove blood and scar tissue. In cases where the retina is detached, they may step in to repair and re-attach the retina (a procedure called the pars plana vitrectomy), thereby saving sight.