Histological changes in the internal retinal layers produced by concussive injuries to the globe. An experimental study.

The level of lesions within the human retina causing transient post-concussive retinal opacification (Berlin's oedema) remains unclear, as histological examination of this tissue is rarely possible before the ophthalmoscopic changes resolve. Studies in vivo of retinae in man and experimental animals previously subjected to blunt, nonperforating mechanical injuries suggest that the development of intracellular oedema may be the principal reason why the retina becomes opaque. The retinae of experimental animals (pigs), whose eyes had been subjected to concussive injuries, were examined histologically after the removal and fixation of the globes, at periods ranging from a few minutes to 7 days after trauma. Disturbances were noted in the inner retinal layers immediately after trauma, which included transient swelling of the mitochondria in the nerve fibres lasting for only a few hours, and marked intracellular oedema of the glial elements which took 2 to 3 days to resolve.