Letter to the editor: partial central retinal artery occlusion offers a unique insight into the ischemic penumbra

Correspondence: David McLeod Emeritus Professor, University of Manchester and Honorary Consultant Ophthalmologist, Academic Department of Ophthalmology, Manchester Royal Eye Hospital, Oxford Road, Manchester M13 9WL, UK Tel +44 0161 440 0737 Fax +44 0161 273 6354 Email [email protected] Kurimoto and colleagues recently reported three cases of unilateral visual loss associated with striking ischemic changes in the posterior retina and impressive visual recovery following treatment. The presenting signs included an indistinct foveal cherry-red spot and a circle of cotton-wool spots (CWSs) surrounding the optic disc. Fundus fluorescein angiography (FFA) revealed a marked delay in the arm-retina circulation time, together with “areas of occlusion of the retinal arterioles” that corresponded to the location of the CWSs. The authors recognized that this was a variant of central retinal artery occlusion (CRAO), but they confessed to being unclear as to the processes underlying this distinctive clinical picture. They surmised that the central retinal artery (CRA) had been incompletely obstructed and that multiple arterioles closer to the capillary network had also been occluded. Thus, the polymorphous CWSs were regarded as “retinal microinfarctions” involving the nerve-fiber layer (NFL), a view that is in line with widely received wisdom in this regard. If this was truly the case, however, simultaneous occlusions of a dozen or more arterioles of differing sizes must have contributed to the fundus appearance, which is unlikely. Kurimoto and colleagues will need to set aside some of the current orthodoxy in the field of ocular vascular occlusive disorders to appreciate the pathophysiological processes at play in their patients.