The term 'choroidal vascular ischaemia' refers to all the choroido-retinal changes which follow an acute or chronic circulatory disorder in the arterial capillary or venous network of the choroid. However, different clinical syndromes can be observed according to the type of vessel which is occluded, the origin and rate of development of the process. Experimentation on animals, especially on monkeys and observations on those with limited retinal pigmentation has enabled us to study the anatomy of the choroidal circulation and the changes found in choroidal vascular ischaemia following capillary embolism or thrombosis after laser. These experiments have been accompanied by histochemical, bioelectrical and genetic examination. For the past 20 years, angiography has been used to study the choroidal circulation, although only cardiogreen and fluorescein have proved useful.