RETROGRADE axonal flow of endocytosed substances, such as released neurotransmitters, from the synapse to the cell body. Owing to its dependence on adenosine triphosphate, retrograde axonal flow is blocked by central retinal artery occlusion.1 Two patients with central retinal artery occlusion and 1 patient with a focal retinal ischemic lesion are described.
In addition to the recognized features of the condition, the first 2 patients exhibited a frequent, although rarely reported, morphologic feature resulting from blockage of retrograde axonal flow. In patient 1, the boundary of ischemia was located around the optic disc, appearing as a whitish ring(Figure 1). In patient 2, who had sparing of the cilioretinal artery, the boundary between viable and ischemic areas was displaced to the edge of the cilio-retinal territory. Consequently, retrograde flow continued into axon segments beyond the optic disc, and aggregation of axoplasmic debris became visible at the border of the vascularized retina(Figure 2). In the third patient, debris had accumulated as a cotton-wool spot, in which a delimiting midline clearly separated debris due to retrograde blockage from debris due to orthograde blockage (Figure 3).