Oct scan head

The retinal structures were visualized using the Micron IV imaging system (Phoenix Research Laboratories, Pleasanton, CA, USA) and an OCT scan head equipped with a mouse objective lens (Phoenix Research Laboratories). The mice were anesthetized with a mixture of ketamine (80 mg/kg; Daiichi-Sankyo, Tokyo, Japan) and xylazine (6 mg/kg; Bayer Yakuhin, Osaka, Japan), and the pupils were dilated with mydriasis containing 1% tropicamide and 2.5% phenylephrine (Santen Pharmaceutical, Osaka, Japan). Hydroxyl ethyl cellulose (Santen Pharmaceutical) was used to prevent dehydration of the cornea. The mice were placed on the bracket, and the optical lens (light source wavelength 830 nm) was moved close to the cornea along the visual axis. Fundus color photographs and OCT images were collected synchronously in real-time. Fundus monochrome photographs were taken with a 488 nm light.

OCT images were taken 1, 3, 7, 14, 30, 90, and 180 days after laser photocoagulation, as were corresponding OCT scans using a Micron IV fundus camera and an OCT Scan Head equipped with a mouse objective lens (Phoenix Research Labs, Pleasanton, CA, USA). The OCT device featured a broadband superluminescent diode at 830 nm, customized for retinal imaging of mice. The scan region on the mouse retina was 1.8 mm in the X and Y directions. Linear OCT scans consisted of a series of 1024 single point A-Scans. Right eyes had previously been dilated with 0.5% tropicamide (Santen Pharmaceutical Co. Ltd., Osaka, Japan) and hydroxyl ethyl cellulose (Senju Pharmaceutical Co. Ltd., Osaka, Japan), used as coupling gel. Images were captured from 20 positions for each eye using StreamPix 6 and Micron OCT commercial software (Phoenix Research Labs). Captured images were quantitatively analysed using “In Sight” software, which can automatically detect and measure each retinal layer. Using this software, the retinal thickness was measured at 20 recorded positions for each eye, and the average of all positions represented the overall retinal thickness.