Pachychoroid Disease: A quick review
In 2013, the term “pachychoroid” was introduced by Warrow et al. in a description of patients manifesting retinal pigment epithelium (RPE) disturbances over areas of choroidal thickening in eyes lacking objective findings indicative of prior episodes of subretinal fluid. The findings of PPE resembled those often found in the fellow eyes of patients with unilateral CSC, which included dilated choroidal veins and choroidal vascular hyperpermeability (CVH) seen with indocyanine green angiography (ICGA). The majority of eyes had “drusenoid RPE lesions,” which, unlike soft drusen seen in typical AMD, had irregular shapes and were usually found as isolated lesions over large choroidal vessels.

Recognition of specific clinical and multimodal imaging findings present in eyes with pachychoroid disease continues to evolve, but many experts have focused on the following features:
-Increased choroidal thickness co-localizing with areas of fundus abnormalities, which may be focal or diffuse.
-Clinically visible dilated choroidal vessels or reduced fundus tessellation in eyes with diffuse choroid thickening.
-Attenuation of the inner choroid in areas of fundus pathology.
-ICGA choroidal hyperpermeability and reduced inner choroidal flow signal shown with optical coherence tomography angiography.
-Pachyvessels (dilated veins of Haller's layer) often co-localizing with overlying disease manifestations.
-Drusenoid RPE lesions (recently renamed “pachydrusen” by Spaide).

In summary, advances in retinal imaging have enabled the recognition that choroidal changes first identified in eyes with CSC seem to influence a much broader range of retinal disease. Since the first description of PPE in 2013, investigators have identified specific changes in choroidal structure which seem to distinguish diseased eyes from those with a benign increase in choroidal thickness. Clinicians should consider the possibility of pachychoroid disease in any patient with RPE changes of the unclear origin or in older patients with presumed degenerative macular changes appearing atypical for AMD.