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C. La Morgia, F. N. Ross-Cisneros, J. Hannibal, G. Cantalupo, S. Heegaard, S. A. Salomão, A. A. Sadun, V. Carelli; Distribution of Melanopsin Containing Retinal Ganglion Cells in Control and Mitochondrial Optic Neuropathy Subjects. Invest. Ophthalmol. Vis. Sci. 2010;51(13):679.
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© ARVO (1962-2015); The Authors (2016-present)
To study the distribution of melanopsin retinal ganglion cells (mRGCs) in human retinas from control subjects and patients with mitochondrial optic neuropathies, for which we previously demonstrated a partial sparing of these cells.
Six eyes from three control subjects (age 54, 58 and 85 years), and five eyes from two patients (age 52 and 59 years) with Leber’s hereditary optic neuropathy (LHON) and one case (age 87) with dominant optic atrophy (DOA) were analyzed. Immunostained mRGCs were manually counted from six sections from each eye representing 5µm thick retinal sections (1 every 5 serial sections) taken sagittally through the optic nerve head with temporal-nasal orientation. The distribution of mRGCs was evaluated, using intervals of 20 degrees, on the nasal and temporal hemiretinas, relative to the fovea (central retina) centred 15 degrees nasal to the optic disc.
Both LHON patients carried the homoplasmic 11778/ND4 mtDNA mutation and were affected by a mild and severe optic atrophy, respectively. The DOA patient carried the 2826delT (p.V942fsX967) mutation in the OPA1 gene and had severe optic atrophy. The overall estimation of the two younger controls showed an increased number of mRGCs in the parafoveal region (p=0.05). A second enrichment in mRGCs was observed at the far end of the nasal hemiretina. In the older control we observed a general loss of mRGCs except for those in the parafoveal region (p=0.005). The analysis of mRGCs distribution in the optic neuropathy subjects shows that, despite an overall absolute loss of mRGCs, more mRGCs remain spared in the parafoveal region (p=0.002). The DOA patient had an almost linear distribution of mRGCs across the entire retina.
The overall comparison of all eleven retinas from controls and optic neuropathy subjects clearly demonstrates a non-uniform distribution of mRGCs, with a significant enrichment in the parafoveal region that is maintained despite neurodegeneration in LHON and ageing. The DOA case reflecting both neurodegeneration and ageing showed a more uniform loss of mRGCs.
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