Background Retinopathy of prematurity is a vasoproliferative disorder that can cause blindness and adverse visual outcomes in extremely premature neonates. Red light at 670nm wavelength promotes cellular differentiation, proliferation and wound repair.

Aims To determine whether 670nm light promotes normal retinal vessel development in a mouse model of Oxygen Induced Retinopathy of Prematurity (OIR) and whether it would affect organ development and growth.

Methods Four groups of C57BL/6J mice were used: 1) Control; 2) OIR - 75% oxygen p7–12 days and normoxia p12–17 days; 3) OIR and 670nm light - 9 J/cm² daily from p7–17; 4) 670nm light - 9 J/cm² daily from p7–17. At p17 animals were sacrificed and retinal vasculature labelled with Lectin. Neovascularisation and vaso-obliteration were analysed using established protocols. Weight and length measurements were taken daily until the animals were sacrificed and all organs were harvested, weighed and examined macro- and microscopically.

Results Neovascularisation was significantly reduced in the 670nm treated OIR group (P<0.05). The 670nm treated mice had increased body weight from p13 but no change in length. The OIR+670nm mice had reduced alveolar haemorrhage in comparison to the OIR only mice (p<0.05).

Conclusions Exposure to 670nm red light appears to promote normal retinal vessel development and may protect against ROP. 670nm treatment may also reduce oxygen induced lung injury.