There are three stages of diabetic neuropathy, says the NHS.
These are background retinopathy, pre-proliferative retinopathy, and proliferative retinopathy.
As the condition moves from one stage to the next, the symptoms worsen until vision loss occurs, loss which can be permanent.
How it is treated
Diabetic retinopathy only requires treatment once it reaches an advanced stage and there is a palpable risk to the patient’s vision.