Proliferative retinopathy can appear after 5 years of diabetes but is usually seen after a longer duration of disease. Patients remain at risk of new vessel formation for their entire lives.

It is vital to appreciate that visual acuity may be unaffected and, therefore, the patient can be unaware of this sight-threatening complication. The likelihood of vitreous haemorrhage increases with the number of new vessels and their proximity to the optic disc (disc new vessels are more likely to bleed).

These vessels can be very obvious...