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M. A. Blasi, B. Falsini, F. Campagna, A. C. Tiberti, P. Valente, E. Balestrazzi; Local Cone-Driven Electroretinograms in Eyes With Choroidal Nevi: A Potential Retinal Bioassay of Tumor Characteristics. Invest. Ophthalmol. Vis. Sci. 2008;49(13):56.
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Recent evidence indicates that amplitude losses in full-field electroretinograms (ERGs) may be associated with choroidal melanomas, possibly as a consequence of tumor-induced fibroblastic growth factor (FGF) overexpression. The aim of this study was to evaluate whether 1. choroidal nevi are associated with a loss of local cone-driven ERGs and, 2. there is a spatial topographic relationship between local ERG changes and tumor location.
Nine patients suffering from unilateral (n = 7) or bilateral (n = 2) choroidal nevi, without any known risk factor for growth, participated in the study. In five patients (six eyes), nevus location was temporal to the macula, whithin vascular arcades. In two patients (two eyes), nevus location was nasal to the optic disc. In two patients (three eyes) nevus location was superior to the macula and outside vascular arcades. Eight age-matched controls were also tested. Cone-driven multifocal ERGs (mfERGs) were recorded in response to the m-sequence modulation of 61 hexagons presented to the central 30 degrees of the retina. Response amplitude densities (RAD) and implicit times of the first order kernel N1-P1-N2 components were measured. Ring (5 rings between 0 and 25 degrees eccentricity) and sector (nasal, temporal superior and inferior fields) analyses were performed
In unilateral cases with temporally-located nevi, the RADs of central (0-2.25 degrees) and pericentral (2.25-10 degrees) retina were reduced by 35% (p<0.05) compared to unaffected fellow eyes. In the unilateral cases with nasally-located nevi, no significant differences in mfERG between affected and fellow eyes were found. In bilateral cases, mfERG response changes depended upon nevus location. There were central and paracentral RAD losses (average 30%) if the nevus was located within vascular arcades, and no losses if the nevus location was outside vascular arcades.
There is evidence that choroidal nevi may affect local cone-driven responses according to their topography. Nevus-associated mfERG changes could be of potential value as a retinal bioassay of nevus characteristics.
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