Comments on: Subretinal drusenoid deposits versus drusen on multicolor imaging

Dear Editor, We read the photo essay by Venkatesh et al. on multicolor (MC) imaging of subretinal drusenoid deposits (SDD). Although the images are appropriate, the essay hypothesizes that SDD and drusen are visualized differently owing to differences in cholesterol composition.[1] SDD being more visible in blue and green reflectance and less so in infrared reflectance on MC imaging has very less to do with their composition and has more to do with their level with respect to the retinal pigment epithelium (RPE). We would like to direct the authors to a very elegant article by Spaide and Curcio about multimodal imaging characterization of different drusen types.[2] SDD is one of the foremost examples in MC imaging, of structures being visible on different reflectance wavelengths due to varying levels in the retina [Fig. 1].Figure 1: (a) Composite image of left eye showing SDD in superior paramacular area. (b and c) BR and GR images (GR>BR) showing the SDD clearly owing to the penetration depth and reflectance properties of the blue and green wavelengths, respectively. (d). IR image not showing the SDD due to the longer wavelength used. The three arrows (blue, green, and red show the different penetration depths in order of wavelength)Even clinically, SDD appear white and hard and soft drusen appear yellow. The RPE absorbs shorter wavelengths of the visible white-light spectrum and structures below the RPE (hard and soft drusen) appear yellow. SDD being above the RPE are not affected by the absorption properties of the RPE and thus appear white. SDD are more prominent on BR and GR because of their sheer location above the RPE and sub-RPE drusen are better visible on IR imaging. This is a very basic differentiation between SDD and sub-RPE drusen and is common knowledge in MC imaging. Financial support and sponsorship Nil. Conflict of interest There are no conflicts of interest.