Orthograde and retrograde axoplasmic transport in retinal ganglion-cell axons can be interrupted by axonal ischaemia. This report is believed to be the first to illustrate how this phenomenon can be obserbed clinically in man in cases of retinal vascular disease. The intense retinal "whiteness" of small cottonwool spots and at the periphery of larger areas of retinal ischaemia represents gross localised axonal distension secondary to the cessation axoplasmic flow.