Choroidal structure in eyes with drusen and reticular pseudodrusen determined by binarisation of optical coherence tomographic images

Purpose: To compare luminal and stromal area of the choroid in eyes with drusen and reticular pseudodrusen (RPD) and to investigate their changes over 24 months. Methods: In eyes with drusen and RPD and control subjects, total choroidal, luminal and stromal area were measured on optical coherence tomography B-scans converted to binary images, at baseline and after 24 months. Results: Eighteen eyes of 18 subjects for each group were included. In drusen and RPD, we found reduction of mean total choroidal (p=0.0005 and p<0.0001, respectively), luminal (p=0.003 and p<0.0001, respectively) and stromal area (p=0.007 and p=0.0002, respectively) from baseline to month 24; no change of ratio between luminal-stromal and the choroidal area was recorded. Mean luminal, stromal and total choroidal areas were reduced in RPD, as compared with drusen and controls at both baseline and month 24 (p<0.05 for all). In RPD, the stromal area was more represented, as we found lower mean ratio of luminal and total choroidal area compared with drusen and control at both baseline and month 24 (p<0.05 for all). Conclusions: Mean total choroidal, luminal and stromal area decreased over 24 months similarly in eyes with drusen and RPD. Mean total choroidal, luminal and stromal area were more reduced in eyes with RPD, as compared with eyes with drusen and controls; however, stromal area was more represented in eyes with RPD suggesting a possible role of choroidal vascular depletion and fibrotic replacement in the pathogenesis and disease progression.