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A.A. Sadun, S.R. Salomao, A. Berezovsky, D.F. Ventura, P. Quiros, F. Sadun, A.M. DeNegri, J. Sherman, T. Lam, V. Carelli; Subclinical Visual Abnormalities Are Common In Carriers With 11778 LHON From A 300 Member Brazilian Pedigree . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1012.
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Purpose: To carefully examine and measure, through a variety of highly sophisticated tests of structure and function, LHON Carriers who had no visual complaints or obvious impairments of vision. Methods: We carefully re–examined 71 carriers of 11778 LHON MtDNA mutant and 77 age matched controls that have been followed for two years as part of our field investigation of this pedigree. Inclusion criteria in both groups were absence of known ophthalmologic or neuro–ophthalmologic complaints and 20/30 or better best corrected VA. All subjects underwent a neuro–ophthalmologic investigation including formal visual fields (Humphrey–HVF) and fundus photography. In addition, many of our subjects underwent sophisticated psychophysical examination including Cambridge Research Systems color vision and contrast sensitivity testing, GDx, HRT, and multifocal (mf) VERs and ERGs. Serological testing for NSE and oxidative stress was also conducted. Results: Most of these LHON Carriers did, in fact, show subclinical or occult abnormalities. In particular, we found microangiopathy (26/71=36%), and focal edema of arcuate nerve fiber bundles (28/71= 39%) in one or more eyes. Corresponding areas of relative paracentral or arcuate scotomas were seen in 30% on HVF testing, and paracentral areas of decreased amplitude on mfERG and mfVER. Further, there were common impairments in color vision (34/46= 74% for protan axis, 35/46= 76% for deutan axis, and 14/46= 30% for tritan axis). Contrast sensitivity testing revealed that 47% had luminance spatial contrast deficits. GDx findings were more common than HRT abnormalities amongst LHON Carriers. GDx abnormalities were seen in 18/71 (25%) and corroborated the fundus and HVF changes as reflected by areas of nerve fiber layer (NFL) swelling or thinning. Finally, a few subjects (8.5%) also demonstrated serological evidence of neuronal distress, but this was not predictable on clinical or psychophysical grounds. Conclusions: In our pedigree of 11778 LHON (J–haplogroup), Carriers manifested several consistent features of retinal and optic nerve impairment. This level of occult disease suggests an ongoing lowgrade compromise in LHON. This form of progression is more common than the classically described dramatic transition from Carrier to Affected.
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