Abnormal morphology of the choroidal vasculature Dilatation of large choroidal vessels 2017-05-10T23:59:11Z Enlargement of the large blood vessels in the choroid. Choroidal thickening can be a feature of central serous chorioretinopathy, amongst other conditions, and results from focal or diffuse dilatation of large choroidal vessels. It is commonly seen in areas of increased choroidal vascular permeability on indocyanine green angiography. Dilated choroidal vessels