Figure 1 shows typical MF-OCT images, including en face projections of structural OCT (
Fig. 1a) and Doppler OCA (
Fig. 1b) and MF-OCT cross sections of structural OCT (
Fig. 1c), Doppler OCA (
Fig. 1d), cumulative phase retardation (
Fig. 1e), and DOPU (
Fig. 1f), obtained from a normal macula of a 27-year-old Chinese male. An OCT en face image (
Fig. 1a) showed the retinal vasculature, and a Doppler OCA image (
Fig. 1b) showed the retinal and choroidal vasculature. A set of MF-OCT cross sections was extracted, as shown in
Figures 1c through 1f from near the fovea (indicated with dotted yellow lines in
Figs. 1a,
1b). Red arrows indicate the retinal vessels; they appeared with hyperscattering in structural OCT (
Fig. 1c), nonzero power Doppler signals (
Fig. 1d), no phase retardation (
Fig. 1e), and high DOPU values (
Fig. 1f). The yellow arrow indicates the RPE level. Retinal pigment epithelium is the bottom-most layer among three hyperscattering layers between the retina and choroid, and it is clearly visualized in the DOPU image as shown in
Figure 1f. Because of the polarization scrambling property of melanin granules in the RPE,
39,40 the RPE appears with low DOPU values, which are generally less than 0.7
38 and appear with a yellowish-green color in the DOPU image, while other retinal tissues have high DOPU
38 values (close to the red color in the DOPU image and generally larger than 0.9). Because the choroid also includes melanin,
48 some part of the choroid also shows low DOPU values. White arrows indicate the location of the chorio-scleral interface (CSI), and the birefringence of the sclera induces an increase in phase retardation.