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J. Sherman, J.M. Roth, P. Quiros, V. Carelli, A. Berezovsky, S. Salomao, F. Sadun, A. DeNegri, R. Belfort, A. Sadun; Retinal Nerve Fiber Layer (RNFL) Assessment and Patterns of RNFL Loss in 200 Members of a LHON Brazilian Pedigree . Invest. Ophthalmol. Vis. Sci. 2003;44(13):939.
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Purpose: 1. To document retinal nerve fiber layer (RNFL) measurements in a recently identified giant Leber’s Hereditary Optic Neuropathy (LHON) pedigree with 11778, J-haplogroup mtDNA and contrast findings in LHON-Affected members, LHON-Carriers, and non-maternally related family members (off pedigree). 2. To report the temporal relationship of acute vision loss and the RNFL loss by comparing those with recent vision loss to those with long-standing vision loss. 3. To assess right/left eye symmetry/asymmetry of RNFL loss. Methods: As part of a comprehensive analysis of over 300 members of a giant LHON pedigree in Brazil spanning 7 generations, RNFL measurements were recently obtained from 200 members. In addition to genetic, epidemiological, neuro-ophthalmic, threshold visual field, F-M 100 color vision, and electrophysiological assessments, RNFL measurements were performed using the new GDx VCC from Laser Diagnostic Technologies. This version of the GDx has a variable corneal compensator (VCC), which reduces artifacts due to anterior segment birefringence. About half of the 200 subjects tested were LHON-Carriers, about 20 were LHON-Affected, and the remainder were off-pedigree. Results: With one exception, all LHON-Affected subjects had profound and quite symmetric RNFL loss. The longer the history of vision loss, the more profound the RNFL loss. All LHON-Carriers had normal or minimally reduced RNFL measurements (that often corresponded to minor field defects and Tritan-axis dyschromatopsia). Essentially all off-pedigree subjects had normal RNFL measurements. Only one LHON-Affected subject had asymmetric RNFL loss. This subject, with bilateral vision loss, was then treated with Alphagan BID in the right eye only for over a year, the same eye with the persistent RNFL. Conclusions: In LHON, functional loss of vision most often precedes (structural) RNFL loss as measured with the GDx. Unlike acute VA reduction, RNFL loss appears to be gradual for the first year and slowly progresses for at least a decade with eventual, profound, and symmetric RNFL reduction. Since the RNFL is normal or near normal at the onset of vision loss, agents with purported neuroprotection can be tested. Monocular treatment with eventual monocular RNFL preservation in the same eye would suggest neuroprotection since untreated subjects develop profound and symmetric RNFL loss.
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