Optimization of laser-induced choroidal neovascularization in the mouse using the Phoenix Micron IV platform

Abstract

Purpose: The mouse model of laser-induced choroidal neovascularization (CNV) has been widely used in studies of the exudative form of age-related macular degeneration using both slit lamp systems and a commercially available new platform, the Phoenix Micron IV. A standardized protocol is needed for consistent results when this model is used in various transgenic mice and for drug screening. We optimized details of laser-induced CNV using the Phoenix Micron IV platform.

Methods: C57BL/6J and 129S6/SvEvTac mice were anestherized by i.p. injection of ketamine/xylazine and dilated with Cyclomydril. Laser photocoagulation of Bruch’s membrane was induced with the Phoenix Micron IV platform, using different laser powers, ages and genders of mice. After 7 days with or without treatment, the mice were sacrificed and choroid was flat-mounted, stained with Isolectin B4 and imaged. Quantification of the size of the neo vessels in laser-induced lesions were performed using an established and constant threshold as appropriate for experiments.

Results: Four lesions with similar sizes can be consistently applied per eye at 2-3 disc diameters away from the optic never using the Phoenix Micron IV platform. The size of lesions is proportional to the power of laser. The lesion size in older mice (>8 weeks) is larger than that in younger mice (6-8 weeks). Female mice have larger laser-induced lesions than male mice in older groups, while there is no significant difference between female and male mice in younger groups.

Conclusions: Laser-induced lesions can be more easily and consistently applied using Phoenix Micron IV platform compared to conditional methods such as slit lamp laser delivery devices. Young mice of either sex at the age of 6-8 weeks are recommended for the mouse model of laser-induced CNV.