Drusen maps for study eye 3. Three retinal specialists independently graded the CFP (unmarked in A) for drusen (B–D). A composite CFP drusen map, representing all areas marked as drusen by at least two of three graders, is represented as (E). To create a projection map of drusen from SD-OCT scans, interpolation of sequential OCT B-scans must be performed. This is because the 6.6 × 6.6-mm field-of-view is sampled by 100 OCT B-scans. Whereas the field of view is represented by 1000 × 1000 pixels in the CFP images (A), there are only 100 × 1000 pixels in the projected OCT markings. (F, G) The interpolated OCT markings using a 2-D cubic interpolation function (MatLab; The MathWorks) and NWE interpolation. Unless otherwise stated, the NWE interpolation (G) was used for comparative analysis in this study.