Diabetic macular oedema (DMO) is a complication of diabetes that affects the eyes. A type of diabetic retinopathy. It occurs when there is swelling (oedema) in the macula, which is the central part of the retina responsible for sharp, central vision. DMO is a common cause of vision loss in individuals with diabetes and is considered a type of diabetic retinopathy.

This is referred to as DME in American English (edema). 

Unit 7,

Reference: Browning DJ, Stewart MW, Lee C. Diabetic macular edema: Evidence-based management. Indian J Ophthalmol. 2018;66(12):1736-1750.