Diabetic macular oedema (DMO) is the leading cause of visual loss in working-aged Americans, and as such successful treatment is of major public health importance. The gold standard is laser photocoagulation based on the landmark Early Treatment Diabetic Retinopathy Study (ETDRS).1 In the ETDRS, laser treatment reduced the 3-year risk of moderate visual loss by 50%; however, the standard teaching is that patients in the ETDRS rarely improved vision. In fact, in the published ETDRS manuscripts to date, only around 10% of patients gained more than three lines of vision. This led to the prevailing thinking that laser prevents vision loss, but rarely results in visual improvement. Thus, newer therapies have been explored in an effort to improve outcomes in this common and devastating condition.

Vascular endothelial growth factor (VEGF) was one of the first cytokines implicated in diabetic retinopathy and DMO with elevated VEGF levels found in patients with active disease.2 Increased retinal capillary permeability due to breakdown of the blood–retina barrier have been shown to be mediated by VEGF.3 Thus, VEGF appears to be a good target to prevent DMO and progression of diabetic retinopathy.

Several anti-VEGF agents have been evaluated in off-label case series and small-scale clinical trials to treat DMO. In a randomised, phase 2 clinical trial of 172 patients, …