Fundus lesions in malignant hypertension. IV. Focal intraretinal periarteriolar transudates.

Experimental renovascular malignant arterial hypertension was produced in 57 rhesus monkeys by a modified Goldblatt's procedure and their eyes were studied by serial ophthalmoscopy, by stereoscopic color fundus photography, and by fluorescein fundus angiography over a period of months or years. A very common, and one of the earliest, lesions in hypertensive retinopathy was focal intraretinal periarteriolar transudates (FIPTs). In the past, FIPTs have been described erroneously as "cotton-wool spots." The two types of lesions differ very much in shape, size, color, location, fluorescein fundus angiographic pattern, resolution pattern, life cycle, and pathogenesis. FIPTs, on ophthalmoscopy, usually are pinpoint to pinhead size, round or oval, dull white in color, and situated in deeper layers of the retina and beside the major retinal arteries and their main branches. On fluorescein angiography, FIPTs show multiple punctate foci of fluorescein leakage from dilated precapillary retinal arterioles, and there is no focal retinal capillary obliteration. They usually last for two to three weeks, and on resolution leave no ophthalmoscopic, angiographic, or microvascular abnormality. Cotton-wool spots are seen in a variety of retinopathies; FIPTs, however, are a specific retinal lesion of malignant arterial hypertension only. They develop due to breakdown of blood-retinal barrier in pre-capillary retinal arterioles, due to dilatation of the arterioles from failure of autoregulation (caused by severe rise of blood pressure).