Pachychoroid

Concept

The term pachychoroid was first introduced by K. Bailey Freund and colleagues when describing a series of eyes showing retinal pigment epithelium (RPE) disturbances associated with an abnormally thick choroid but occurring in the absence of subretinal fluid. They termed these findings “pachychoroid pigment epitheliopathy” and suggested that it might be considered a forme fruste central serous chorioretiopathy. However, defining what should be considered pathologic increases in choroidal thickness is difficult since “normal” may depend on age, spherical equivalent and axial length, and even on the circadian rhythm. In addition, different systemic treatments and disorders, and local diseases can cause fluctuations in choroidal thickness. For these reasons, the term pachychoroid has evolved to encompass not only an abnormally thick choroid, but, more importantly, a focally or diffusely thickened Haller layer inducing secondary and variable compression on the overlying Sattler layer and choriocapillaris. The dilated Haller layer vessels have been termed “pachyvessels.”

Although there is a myriad of ocular diseases that are associated with increased choroidal thickness, the aim of the present chapter is to describe the main features of the newly described pachychoroid pigment epitheliopathy and pachychoroid neovasculopathy.

Definition

Pachychoroid pigment epitheliopathy is characterized by the presence of retinal pigment epithelial abnormalities associated with focal or diffuse increase of choroidal thickness and dilated Haller layer vessels (pachyvessels), without any evidence of ongoing or antecedent subretinal fluid.

Fundus Imaging Features