 This study will enrol patients who have already decided to undergo an eye operation pars plana vitrectomy to clear a persistent diabetic vitreous haemorrhage. Those in the treatment arm will have an intravitreal injection of ranibizumab at the same dose used for nAMD. It is hypothesised that this will promote clearance of the vitreous haemorrhage and that this, in turn, may mean that some patients do not need to proceed to vitrectomy. 