Pachychoroid disorders of the macula

The disease mechanisms are not completely understood. All pachychoroid disorders of the macula show choroidal thickening and congestion with increased blood vessel diameter, especially in the deep choroid (the so-called Haller's layer). This results in increased pressure from the deep choroid against the superficial choroid close to the retina, damaging the fine blood vessels (capillaries) needed to supply oxygen and nutrients to the retinal pigment epithelium and retina. Additionally, fluid can leak from these damaged vessels and accumulate under the retina. == Types of pachychoroid disorders ==

Uncomplicated pachychoroid If only choroidal thickening is observed, usually to values exceeding 350 or 300 μm, but no damage to the surrounding structures is detected, eyes are classified as having an uncomplicated pachychoroid. It is assumed that a large part of the population has a thickened choroid without other signs of disease. This includes mainly young and far-sighted people, as choroidal thickness decreases with age and increasing axial length of the eye causing near-sightedness (myopia). This stage is called pachychoroid neovasculopathy (PNV), [4] which can cause a massive reduction in vision due to bleeding and scarring of the macula. Anti-VEGF therapy, which is injected directly into the eye (intravitreally), has proven to be an effective therapy in this case. • If parts of the CNV vessel wall bulge outward, so-called aneurysms develop. This stage is called pachychoroidal aneurysmal type 1 CNV (PAT1), still widely referred to as polypoidal choroidal vasculopathy (PCV). This stage is the most aggressive one, causing irreversible vision loss due to a destruction of the macula, frequently involving retinal hemorrhage. Intense anti-VEGF-therapy, often in combination with a special laser treatment (photodynamic therapy) is effective to restore visual loss and/or slow visual decline. • In all stages, focal choroidal excavation may occur, which probably represents a contraction of the choroid due to scarring processes. Beyond the spectrum of pachychoroid disorders of the macula, pachychoroid phenotypes have also been described around the optic disc, causing fluid retention in the retina (peripapillary pachychoroid). == Classification ==

The individual stages of the pachychoroid disease spectrum of the macula develop sequentially from the respective preliminary stage, and can partially recede with therapy. According to Siedlecki, Schworm and Priglinger, this disease continuum can be classified into four stages == References ==