Laser-Induced Retinal Lesions in Mice

Mice were anesthetized with a mixture of xylazine (6 mg/kg) and ketamine (100 mg/kg), and pupils were dilated with topical drops of Cyclomydril (Alcon Laboratories, Fort Worth, TX). Two minutes after pupil dilation, lubricating eye drops (Alcon Laboratories) were applied to the cornea. The fundus was viewed with an imaging camera, and laser photocoagulation was induced using the image-guided laser system (Micron IV, Phoenix Research Laboratories, Pleasanton, CA). The fundus image as well as the aiming beam can be observed on the monitor screen. Four laser burns at equal distance from the optic nerve were induced one by one in each eye by a green Argon laser pulse with a wavelength of 532 nm, a fixed diameter of 50 μm, duration of 70 ms, and varying power levels from 180 mW to 360 mW. If necessary, an orienting laser shot can also be generated approximately three times of the diameter of the optic nerve to help determine the relative positions of the lesions in an eye. After laser photocoagulation, the eyes were gently rinsed with sterile saline to remove the lubricating eye drops and treated with an antibiotic ointment, erythromycin (Fougera, Melville, NY). Mice were then placed on a pre-warmed warming plate at 35°C after the laser treatment until they awakened.