Purpose: Vascular endothelial growth factor‐A (VEGF‐A) is crucial to retinal vascular growth, both normal and pathological. VEGF‐B, recently characterized, is reported to be expressed in retinal tissues, but the importance of VEGF‐B to retinal vascular development remained unknown. The aim of this study was to analyse retinal vascular growth in the Vegfb^−/− knockout mouse.

Methods: Retinal vascular growth was measured in Vegfb^−/− knockout mice raised under normal conditions, and Vegfb^−/− knockout mice with an oxygen‐induced proliferative retinopathy. Wild type Vegfb^+/+ mice served as controls. Vessels were perfused with ink and retinal flatmounts secondarily labelled with FITC‐lectin (BS‐1, Griffonia simplicifolia). Area and diameter of retinal growth and retinal vascular growth were recorded over days 0−20, and capillary density and mean diameter recorded from day 17 pups.

Results: A variety of techniques confirmed that Vegfb^+/+ mice expressed VEGF‐B and that VEGF‐B expression was absent in Vegfb^−/− mice. Vegfb^−/− mice raised in room air showed no significant differences from Vegfb^+/+ controls. No differences were found in oxygen‐induced retinopathy between Vegfb^−/− and Vegfb^+/+ pups in either the extent of the initial oxygen‐induced ablation, or in the regrowth of retinal vessels or vitreal (neovascular) sprouts; vitreal sprouts are important markers of the abnormal proliferative response, and are maximally expressed on day 17 in this model of oxygen‐induced retinopathy.

Conclusions: These results indicate that a lack of VEGF‐B does not significantly affect development of the retinal vasculature under normal conditions, nor does it appear to affect the proliferative retinal responses seen in oxygen‐induced retinopathy.