Mitochondrial optic neuropathies

Mitohondrial optic neuropathies are a heterogenous group of disorders that present with visual disturbances resultant from mitochondrial dysfunction within the anatomy of the Retinal Ganglion Cells (RGC), optic nerve, optic chiasm, and optic tract. These disturbances are multifactorial, their aetiology consisting of metabolic and/or structural damage as a consequence of genetic mutations, environmental stressors, or both. The three most common neuro-ophthalmic abnormalities seen in mitochondrial disorders are bilateral optic neuropathy, ophthalmoplegia with ptosis, and pigmentary retinopathy. Mitohondrial optic neuropathies are a heterogenous group of disorders that present with visual disturbances resultant from mitochondrial dysfunction within the anatomy of the Retinal Ganglion Cells (RGC), optic nerve, optic chiasm, and optic tract. These disturbances are multifactorial, their aetiology consisting of metabolic and/or structural damage as a consequence of genetic mutations, environmental stressors, or both. The three most common neuro-ophthalmic abnormalities seen in mitochondrial disorders are bilateral optic neuropathy, ophthalmoplegia with ptosis, and pigmentary retinopathy. The generalized, common presentation for this broad and inclusive group of diseases is painless, bilateral loss of visual acuity and pallor of the optic disc accompanied with varying degrees of dyschromatopsia and central/cecocentral scatomas. On examination the papillary response may be sluggish to light, one would not expect to find an afferent papillary defect. This is because optic neuropathies are often bilateral and symmetric. The optic disc may be mildly hyperemic with small splinter hemorrhages on or around the disc. Optic atrophy may early on be non-existent and only later become mild. In later stages the optic atrophy is severe and this indicates less opportunity for recovery. The duration of onset can vary between immediate and insidious, owing to the specific etiology. Two key features may be helpful in distinguishing acquired from inherited optic neuropathies: absence of a family history and simultaneous involvement of both eyes; the former more commonly characterized by these two features.