Purpose:
To evaluate the long-term consequences of retinal haemorrhage in the young pigmented rat.
Methods:
A spontaneous model of retinal haemorrhage which was discovered in this laboratory was evaluated longitudinally by means of fundus photography. Final pathology was evaluated histologically and by immunocytochemistry.
Results:
We demonstrate bleeding in the eyes of all rats examined (n=95). Fundus photographs (see image) revealed that bleeding commenced at around 2 weeks of age and active bleeding appeared to cease at around 6 weeks of age. Cells of the monocyte lineage including macrophages were subsequently observed at the sites of bleeding, and haemosiderin-containing macrophages persisted for at least 12 months at such sites. Photoreceptor degeneration was observed at approximately 9 months post-haemorrhage, with subsequent anomalies in vascularization and glial cell reactivity.
Conclusions:
Haemorrhage in the retina leads to a slow degenerative phenotype with features that are comparable to aspects of AMD. We suggest that activation of the clotting cascade, which co-activates the complement cascade, may be an initiating factor in the degenerative process in this model, and possibly in human AMD.
Keywords: blood supply • degenerations/dystrophies • microglia