The earliest changes are called background retinopathy. Small changes develop on the blood vessels and look like tiny red dots. These are called
microaneurysms. Larger red dots are called retinal haemorrhages. They lie within the retina and are very like a bruise on your skin. Background retinopathy does not affect your sight and does not need treatment. However, you should make sure that you go for screening every year and control your diabetes well.
As time goes by, your blood vessels may become constricted and the retina may become starved of oxygen and nutrition. Different signs can be seen in the retina at different stages during this progression. These are called pre-proliferative retinopathy and requires more frequent follow ups.
Eventually you may develop new blood vessels on the retina. This is called proliferative diabetic retinopathy. At this stage your sight is at risk as the vessels may bleed or may develop scar tissue. This can pull the retina away from the underlying layers of the eye, causing a traction retinal detachment. If the new vessels bleed, you may see a sudden shower of floaters or cobwebs in your sight, or your sight may be completely blurred. This is called a vitreous haemorrhage.
If you develop proliferative retinopathy or if you are very close to developing proliferative retinopathy, you will be advised to have laser treatment.

You may also suffer from changes in the blood vessels at the macula. The commonest change is that the blood vessels become leaky. Fats and fluid that are normally carried along in the bloodstream may then leak into the macula. Fats that have leaked into the retina are called exudates. Fluid leaking causes waterlogging in the retina and is called “oedema”.
Oedema at the centre of the macula ( Diabetic Maculopathy or Macular Oedema ) will cause you to lose some sight and you may need gentle laser treatment or an injection in the back part of the eye ( Intravitreal Triamcinolone , Intravitreal Anti VEGF or Macugen)