Figure 2.

TEM. The anterior segment of the enucleated and fixated eye ball (a) was embedded in araldite and sectioned at three optic nerve disc (ON) centered levels (b). The sections were placed on a copper grid with an intergrid-distance of 150 μm. Grid bars were counted starting from the first grid bar that covered a piece of retina that showed all outer retinal layers in the right anatomical order (the second grid bar shown in scheme c). Therefore, the maximum distance of picture one from optic disc was 300 μm, the minimum distance 150 μm. All pictures were taken within an optic disc centered radius of 450 μm. Three pictures (12,000-fold magnification) to both sides of the optic nerve of each section were taken (d) always in front of the first and in front of and behind the second grid bar (black middle bar) generating a total of six pictures per section. Within each picture, three measurements of BrM thickness were conducted (e, f). The thereby determined BrM thickness is a result of 54 measurements per eye. An overview picture (3000-fold magnification) of each level was taken to examine ultrastructural integrity of RPE before BrM thickness was measured in higher magnification.