Low power laser treatment of the retina ameliorates neovascularisation in a transgenic mouse model of retinal neovascularisation

This study was designed to determine if low power laser therapy can achieve amelioration of vasoproliferation yet preserve useful vision in the treated area in a transgenic mouse model of retinal neovascularisation. The mice were anaesthetised and the pupils dilated for ERG and fundus fluorescein angiography on postnatal day 32. The left eyes were treated with approximately 85 laser spots (532 nm, 50 ms, 300 μm diameter) at a power level of 20 mW at the cornea. The eyes were examined using ERG and fluorescein angiography, one, four and six weeks later. Flat mounts of FITC-dextran infused retinas, retinal histology and PEDF immunohistochemistry was studied one or six weeks after laser treatment. In untreated eyes the expected course of retinal neovascularisation in this model was observed. However, retinal neovascularisation in the laser treated eye was significantly reduced. The laser parameters chosen produced only mild lesions which took 10–20 s to become visible. ERG responses were comparable between the treated and untreated eyes, and histology showed only partial loss of photoreceptors in the treated eyes. PEDF intensity corresponded inversely with the extent of neovascularisation. Low power panretinal photocoagulation can inhibit retinal neovascularisation and yet preserve partial visual function in this transgenic mouse model of retinal neovascularisation.