How Does Diabetes Affect the Eyes?

Diabetes causes changes in the blood vessels throughout the body, including those in the eyes. Chronically elevated blood sugar levels can damage the tiny blood vessels (capillaries) in the retina — the light-sensitive layer at the back of the eye.

The main eye conditions associated with diabetes include:

  • Diabetic retinopathy — Damage to the retinal blood vessels
  • Diabetic macular oedema (DMO) — Swelling of the macula (central retina) due to fluid leakage
  • Increased risk of cataract
  • Increased risk of glaucoma
  • Fluctuating vision — Due to changes in blood sugar affecting the lens

What Is Diabetic Retinopathy?

Diabetic retinopathy is the most common diabetic eye complication. It occurs when high blood sugar damages the blood vessels in the retina, causing them to leak, swell, or in advanced stages, to grow abnormally (proliferative diabetic retinopathy).

Diabetic retinopathy is classified into stages:

  • Mild non-proliferative diabetic retinopathy (NPDR) — Early changes including small bulges in retinal blood vessels (microaneurysms)
  • Moderate NPDR — More widespread retinal changes
  • Severe NPDR — Significant blockage of retinal blood vessels
  • Proliferative diabetic retinopathy (PDR) — Growth of new, fragile blood vessels that can bleed and cause serious vision complications

Symptoms of Diabetic Eye Disease

A critical aspect of diabetic retinopathy is that it often causes no noticeable symptoms in the early stages. Symptoms that may develop as the condition progresses include:

  • Blurred or fluctuating vision
  • Dark spots or floaters in vision
  • Difficulty seeing colours accurately
  • Dark or empty areas in the visual field
  • Sudden vision loss (in advanced cases)

Because early diabetic retinopathy may be present without any of these symptoms, regular screening is essential.

Why Is Regular Screening Important?

Regular retinal screening is the most reliable way to detect diabetic eye changes before they cause noticeable vision loss. When detected early, many cases of diabetic retinopathy can be managed to slow progression and protect vision.

Annual diabetic eye screening is generally recommended for people with both Type 1 and Type 2 diabetes. More frequent screening may be recommended if changes are detected or if other risk factors are present.

Managing Diabetic Eye Disease

Management of diabetic eye disease involves both systemic and local approaches:

  • Optimising blood sugar control (HbA1c management)
  • Blood pressure control
  • Cholesterol management
  • Regular retinal screening and ophthalmologist follow-up
  • Treatment of retinal changes when indicated (laser treatment, anti-VEGF injections, or surgery depending on stage and type)