ME can occur if the swelling, leaking, and hard exudates noted in BDR occur within the macula, the central 5% of the retina most critical to vision. The white areas in the picture are components of the blood which have leaked out of the weak vessel walls. This very small area is rich in cones, the nerve endings that detect color and upon which daytime vision depends. Blurring occurs in the middle or just to the side of the central visual field, rather like looking through cellophane. Visual loss may progress over a period of months, and can be very annoying because of the inability to focus clearly. ME is a common cause of severe visual impairment.
Use the Amsler grid to check your eyes for macular edema.