Oxygen-induced retinopathy: a model for vascular pathology in the retina.

Ischaemic vascular disease in the retina may either leave retina permanently ischaemic with slow degradation of vision, or alternatively lead to proliferative vascular disease, which can also destroy vision. To investigate the molecular and cellular mechanisms that contribute to this pathology a mouse model has been studied extensively. The model is based on the exposure of mouse pups to hyperoxia during a phase when their retinal vasculature is still developing. This leads to capillary depletion, and upon return to room air, results in retinal ischaemia and proliferative vascular disease in the retinal vasculature (oxygen-induced retinopathy (OIR)). Numerous studies using this OIR model have revealed that the regulation of angiogenic factors and the influence of inflammatory cells play a pivotal role in the vascular pathogenesis. It has also been demonstrated in the OIR model that proliferative vascular disease is not the only possible outcome of ischaemia-induced angiogenesis in the retina, but that ischaemic areas in the retina can be revascularised with healthy blood vessels. Therefore, understanding the factors that control the balance between pathological and healthy angiogenesis in the OIR model may have important implications for human retinal ischaemic disease.