Morphology of early retinal lesions after experimental venous occlusion

Abstract

Study of early hystological lesions after experimental branch venous occlusion (BVO) in miniature pigs. The retina was taken 1, 2, 4, 6 and 8 hours after BVO with green argon laser for examination with conventional and electronic microscopy. 1 hour after occlusion an extracellular focal oedema is observable in the ganglion cells optic nerve fibers and cells of inner plexiform layer; 2 hours after occlusion there is also an extracellular oedema of the external plexiform layer as intracellular oedema of the inner nuclear layer, 4 hours after occlusion the extracellular oedema is more diffuse especially in the ganglion cells, inner nuclear and optic nerve fibers layers. Cytoplasmic vacuolisation, nuclear pycnosis and ruptured cell membrane layers are observed; 8 hours after occlusion both intra and extracellular oedema are observable throughout the inner retina. After BVO histological lesions are found within one hour only following the occlusion, apoptosis and cell necrosis are present as soon as 4 hours after experimental BVO.