Change at 24 months compared with baseline in functional factors ( frequency doubling perimetry [ FDP ] , Humphrey photopic Swedish Interactive Thresholding Algorithm 24-2 testing , contrast sensitivity , dark adaptation , visual acuity , and quality of life ) and anatomic factors ( Early Treatment Diabetic Retinopathy Study DR severity level , area of retinal thickening , central macular thickness , macular volume , and retinal vessel diameters ) .