Figure 1. Morphology of the canine retina. Morphology of the peripheral retina in a healthy dog (A) and dog with advanced glaucoma (B). Glaucomatous changes include dramatic loss of cells in the retinal nerve fiber layer, ganglion cell layer and inner nuclear layer compared to healthy eyes. In the glaucomatous retina GFAP can readily be detected in retinal glial cells (arrows) and indicates extensive gliosis in the nerve fiber layer. GFAP can also be detected in the NFL of normal eyes when extended periods of color development are used. (NFL-nerve fiber layer, RGC-retinal ganglion cell layer, IPL-inner plexiform layer, INL-inner nuclear layer, OPL-outer plexiform layer, ONL-outer nuclear layer, OS-Photoreceptor cell outer segments).