A. Schematic diagram of a cross section of a rodent eye cut through the optic nerve head. The thick black line in the posterior part of the globe represents the retina. Measurements were taken from i) the central portion of the retina: 960 µm from the optic nerve head (ONH), and ii) the peripheral portion of the retina: 960 µm from the ora serrata, along the superior and inferior axis of the globe. Each marked interval represents ∼960 µm. B. Photomicrograph of an H&E stained retinal section to illustrate the measurements taken from different retinal layers for quantitative analyses. Inner retina is up. 1 = retina thickness (RT) = inner limiting membrane (ILM) to outer limiting membrane (OLM), 2 = inner nuclear layer (INL), 3 = outer nuclear layer (ONL), 4 = inner and outer segments (IOS) of rod cells. To minimize the effects of uneven tissue shrinkage among eye samples, we normalized the thickness of INL, ONL, and IOS by comparing these measurements with the overall thickness of the retina (RT). Measurements from a single retinal section were taken using a calibrated reticle on one of the binoculars of a Nikon E400 microscope under a 20X objective. Averages were from eyes of different animals.