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Editors Selection IGR 15-4

Differential Diagnosis: LHON

Comment by Yeni Yucel on:

19273 Is second eye involvement in Leber's hereditary optic neuropathy due to retro-chiasmal spread of apoptosis?, Edwards TL; Buttery RG; Mackey DA, Neuro-Ophthalmology, 2007; 31: 87-94

Find related abstracts

Ewards et al. (878) present five cases of Leber's hereditary optic neuropathy (LHON) out of a large Australian series, that presented with unilateral pathology. In the first three cases with mtDNA mutations at either 3460 or 11778, a unilateral insult to the retina preceded LHON development, affecting also the contralateral eye within three to eight months. The fourth case, a carrier of the 11778 mutation, did not develop optic neuropathy following central retinal vein occlusion. The last case had no history of retinal insult, and belonged to a pedigree with the 14484 mutation. Four visual fields taken at early disease stages were presented and showed left visual field loss and minimal right field involvement with progressive changes in the right visual field over a period of nine months. The authors suggest that the pattern of visual field progression to the right eye is a result of spread of damage via retro-chiasmal pathways ie. RGCs from the nasal hemi-retina in one eye, cross the chiasm, and affect RGCs originating from the temporal hemi-retina of the fellow eye. This is an interesting hypothesis, however further research on similar cases with MRI assessment of the retrochiasmal pathways is needed to test this hypothesis. In experimental unilateral optic nerve injury, astrocytic and microglial changes have been observed in the fellow retina,¹ and immune mechanisms have been implicated. Although the association between autoimmune disease and LHON remains controversial,^2-4 the involvement of immune mechanisms in the spread of disease to the fellow eye cannot be excluded in these reported cases. Additionally, although the majority of mutations affect complex 1 of the mitochondrial respiratory chain, different specific mtDNA mutations may predispose to varying phenotypes of susceptibility and progression. Monitoring visual fields in LHON at early disease stages may help to better characterize and understand progression to bilateral vision loss in LHON.

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