Fundus examination of the healthy and affected calves. In healthy calf, the surface of optic disc is flat, and the edge is clear and visible (Figure 1A). No edema, hemorrhage, exudation and disorder of pigment were found in retina (Figure 1B). The irregular pigmentation was present with varied sizes at local areas in the tapetum nigrum (Figure 1C) and tapetum lucidum (Figure 1D), and more obvious in the tapetum nigrum than in the tapetum lucidum. The black arrow in the figure 1C means that pigmentation was present in the tapetum nigrum and that in the figure 1D means that pigmentation was present tapetum lucidum.
He et al. BMC Veterinary Research 2012 8:222 doi:10.1186/1746-6148-8-222