New insights on 'pachychoroid spectrum'

Central serous chorioretinopathy (CSC) is the diagnosis that usually comes to mind when retinal specialists see an eye with choroidal thickening. New insights on choroidal pathology obtained using advanced imaging techniques, however, have led to the description of a broader group of pachychoroid diseases, said K. Bailey Freund, MD, at the inaugural Retina World Congress.

In addition to CSC, this “pachychoroid spectrum” includes pachychoroid pigment epitheliopathy (PPE), focal choroidal excavation (FCE), pachychoroid neovasculopathy (PCN), and polypoidal choroidal vasculopathy (PCV).

 

Multimodal imaging of pachychoroid pigment epitheliopathy. (Figure courtesy of K. Bailey Freund, MD)

Multimodal imaging of pachychoroid neovasculopathy/polypoidal choroidal vasculopathy. (Figure courtesy of K. Bailey Freund, MD)

 

 

 

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“The four newer entities in the pachychoroid spectrum share choroidal features with CSC, but they can look very different in that they can mimic and/or modify the course of age-related macular degeneration (AMD),” said Dr. Freund, clinical professor of ophthalmology, New York University School of Medicine, New York.

“It is important for retinal specialists to be aware of these pachychoroid diseases and to evaluate the choroid carefully using multimodal imaging, particularly when patients are clinically atypical for AMD.”

Defining characteristics

The anatomic features of the pachychoroid phenotype include reduced fundus tessellation in areas of choroidal thickening that is noted clinically or on fundus photography.

In addition, there is a diffuse or focal increase in choroidal thickness and dilated outer choroidal vessels that do not taper within the areas of thickened choroid (“pachyvessels”) seen with en face swept-source optical coherence tomography (OCT); and attenuation and thinning of the choriocapillaris and Sattler’s layer vessels overlying the pachyvessels visualized on enhanced depth imaging OCT or swept-source OCT. Indocyanine green (ICG) angiography will show mid-phase choroidal hypermeability (staining of the choroidal stroma).

“Although the term pachychoroid describes a thickened choroid, it is important to note that the thickening is associated with the development of large dilated vessels while these patients are losing some of the inner choroid that provides nutritional support to the overlying retina,” Dr. Freund said.

PPE, CSC, and FCE can manifest early in adulthood. PPE, which can be considered a forme fruste of CSC, and FCE are characterized by focal RPE changes in the macula within areas of thickened choroid. In contrast to CSC, subretinal fluid is absent in PPE.

Dr. Freund noted that PPE is a very common incidental finding and often misdiagnosed.

“I see several new patients with PPE every week in clinical practice,” he said.

“It is often mistaken for early AMD, atypical pattern dystrophy, punctate inner choroidopathy, or retinal pigment epitheliitis," he said. "Reduced fundus tessellation is a clue to the diagnosis of PPE, and patients will also be atypically young for AMD and lack drusen. Multimodal imaging is needed, however, to definitively differentiate PPE from the other disorders.”

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