A drop of Flura-Safe Fluorexon Disodium & Benoxinate Hydrochloride Ophthalmic Solution 0.35%/0.4% (Apollo Ophthalmics, Newport Beach, CA, USA) was placed over the mouse eyeballs for 1 minute, and the excess removed with PBS washes. The eyeballs were imaged using a Zeiss Discovery.V12 Stereo Microscope (Zeiss). At least seven eyeballs were used for each experimental point.