A 29-year-old man with IDDM for the last 14 years develops sudden vision loss and has nonproliferation diabetic retinopathy, cause is

(A) Macular oedema # DIABETIC MACULOPATHY: Changes in macular region need special mention, due to their effect on vision.> These changes may be associated with Non-Proliferative Diabetic Retinopathy(NPDR) or Proliferative Diabetic Retinopathy (PDR).> Diabetic macular edema occurs due to increase permeability of the retinal capillaries.> It is termed as Clinically Significant Macular Edema (CSME) if one of the following three criteria are present on slit-lamp examination with 90D lens Thickening of the retina at or within 500 micron of the centre of the fovea. Hard exudate at or within 500 micron of the centre of fovea associated with adjacent retinal thickening Development of a zone of retinal thickening one disc diameter or larger in size, at least a part of which is within one disc diameter of the foveal centre.