OPA1 and Leber hereditary optic neuropathy: Other diseases with primary involvement of parvocellular axons comprise the so called non-syndromic mitochondrial optic neuropathies such as Leber's hereditary optic neuropathy (LHON) and OPA1 related dominant optic nerve atrophy (DOA) and toxic and nutritional optic neuropathies such as tobacco-alcohol amblyopia or ethambutol-induced optic neuropathy [21].