<unk>  is damage to the optic nerve from any cause. Damage and death of these nerve cells, or neurons, leads to characteristic features of<unk> . The main symptom is loss of vision, with colors appearing subtly washed out in the affected eye. On medical examination, the optic nerve head can be visualised by an ophthalmoscope. A pale disc is characteristic of long-standing<unk> . In many cases, only one eye is affected and patients may not be aware of the loss of color vision until the doctor asks them to cover the healthy eye.<unk>  is often called optic atrophy, to describe the loss of some or most of the fibers of the optic nerve. In medicine, "atrophy" usually means "shrunken but capable of regrowth", so some argue that "optic atrophy" as a pathological term is somewhat misleading and the term<unk> " should be used instead. In short, optic atrophy is the end result of any disease that damages nerve cells anywhere between the retinal ganglion cells and the lateral geniculate body (anterior visual system).
Optic neuropathy
Auditory neuropathy
Retinal degeneration 
Optic neuritis
Anterior ischemic optic neuropathy
Vitreoretinopathy
Posterior ischemic optic neuropathy
Ischemic optic neuropathy