Commentary: Pachydrusen in polypoidal choroidal vasculopathy in an Indian cohort.

Ever since Richard Spaide described a new drusen called pachydrusen based on the morphology and associated with pachychoroid, there has been a lot of interest in understanding the clinical significance and its association in various pachychoroid disorders.[1] The term pachychoroid came from the Greek word pachy (meaning thick) and it was used to describe a spectrum of disorders associated with increased thickness of the choroid.[2] However, recently Cheung CMG and her group have redefined the term pachychoroid as not just an increase in the thickness of the choroid but more importantly morphological changes within the choroid, namely, the presence of pachyvessels at the Haller layer and associated compression of the overlying choriocapillaries, and thus resulting in the morphological changes in the retinal pigment epithelium.[3] Therefore, the terms pachychoroid and pachychoroid spectrum are in a stage of evolution and learning. In this context, the article by Singh et al. tries to elucidate the prevalence of pachydrusen in a cohort of patients with polypoidal choroidal vasculopathy (PCV).[4] Pachydrusen are >125 μm in diameter with jagged outer margin, located throughout the posterior pole. They may be single or in group of few. These features make pachydrusen different from conventional soft drusen which typically aggregate in the central macula. Pachydrusen are associated with a thick choroid with an average subfoveal choroidal thickness of 419 μm.[1] The two important observations in the article by Singh et al. are low prevalence of pachydrusen 14% in eyes with PCV and a mean subfoveal choroidal thickness of 298 μm.[4] Lee and Byeon reported a prevalence of 49.3% of pachydrusen in PCV with a mean foveal choroidal thickness of 403 μm.[5] Around 70% of the eyes in the report by Singh et al. had hemorrhagic PCV and this could mask the presence of pachydrusen. This probably explains the low incidence of pachydrusen in this series. It would have been interesting if they would have looked into the morphology of the choroid underlying the pachydrusen. Baek et al. have reported the presence of pachyvessels along with increased thickness of the choroid under the pachydrusen.[6]

Be that as it may, the article has kindled an interest in the new drusenoid form. Further work in a larger spectrum of cases which includes all form of the pachychoroid spectrum including central serous chorioretinopathy will give us a better understanding of the significance, relevance, and importance of pachydrusen in clinical practice.