Figure 3

The nine sectors based on the Early Treatment Diabetic Retinopathy Study (ETDRS). Circles are centered around the fovea with diameters of 1, 3 and 6 mm, respectively. Indexes in the sectors refer to their locations as follows: S = superior, N = nasal, I = inferior, T = temporal. Sectors marked with ‘1’ (S1, N1, I1 and T1) are in the inner circle, sectors marked with ‘2’ (S2, N2, I2 and T2) are in the outer circle. Sector ‘C’ represents the central area. This figure illustrates a right eye. The sector numbers in the text correspond to the grid sectors on this illustration as follows: 1 = C, 2 = I1, 3 = T1, 4 = S1, 5 = N1, 6 = I2, 7 = T2, 8 = S2, 9 = N2.