Key points for diagnosis1. Clinical Manifestations(1) The vision is obviously diminished and the light perception disappears.(2) The pupillary light reaction is slow or even disappears in terms of the pathogenic changes.(3) The fundus examination finds that the optic disc becomes pale or whitish pale or wax yellow with clear or unclear boundaries, that the retinal vessels turn thin, and that there exist a large number of atrophic foci or spots of pigmentation in the retina.(4) The visual field is of concentric diminution which is obviously characterized by red and green diminution. Sometimes, there may appear obvious central scotoma, fan-like defect and biocular temporal hemianopia or homonymous hemianopia. The changes of visual field and diminishment of vision synchronize.2. Laboratory Examinations(1) Electrophysiological examination of the visual function The wave form of the evoked potential of figure vision or flashing vision is clearly low. The potential peak time is prolonged and the wave is even absent. The wave of the figure electroretinogram is reduced or totally disappears while that of the flasing electroretinogram may appear normal. .(2) Fluorescein fundus angiography At the beginning, there is no abnormal finding in the examination but, in the course of the disease, the fluorescein of optic disc, when examined, usually becomes weak till the strong fluorescein of optic disc is found because of the effusion of papillary vessels at the late stage.