This develops as a result of hyperglycaemia-induced vascular damage resulting in breakdown of the inner blood-retinal barrier and leakage of fluid into the retina. Risk factors for progression include raised HbA1c, increased diastolic blood pressure and gross proteinuria. Once started, the condition tends to progress. Usually, the condition is treated with laser, but improvements in vision are rarely observed.

Prevention
Intensive control of blood sugar with HBA1c below or equal to 7% has been shown to prevent progression.  Switching type 2 diabetics to insulin increases the incidence of diabetic macular oedema in the short term. We believe that angiotensin II converting enzyme inhibitors and fenofibrate may slow progression, but convincing data is not yet available.