ABSTRACT
Some electrophysiological tests are helpful in the assessment of visual disorders. The physiological basis, technical aspects and general indications of those available at most neurophysiology services are reviewed. The Full-Field electroretinogram reflects photoreceptor and inner retinal function. The Pattern electroretinogram assesses retinal ganglion cell function and can identify macular dysfunction mimicking optic nerve disease. The electro-oculogram is a test of function of the outer retina and retinal pigment epithelium; it differentiates Best's disease from all other bestrophinopathies. Visual evoked potentials evaluate the visual pathway and are especially helpful in the evaluation of the optic nerve.
Subject(s)
Electrooculography , Electroretinography , Evoked Potentials, Visual , Vision Disorders/diagnosis , HumansABSTRACT
Autosomal recessive retinitis pigmentosa (ARRP) is a genetically heterogeneous disease. To date, mutations in four members of the phototransduction cascade have been implicated in ARRP. Additionally, linkage of the disease to three loci on 1p, 1q, and 6p has been described. However, the majority of cases are still uncharacterised. We have performed linkage analysis in a large nuclear ARRP family with five affected sibs. After exclusion of several regions of the genome known to contain loci for retinal dystrophies, a genomic search for linkage to ARRP was undertaken. Positive lod scores were obtained with markers on 2q31-q33 (Zmax at theta = 0.00 of 4.03, 4.12, and 4.12 at D2S364, D2S118, and D2S389, respectively) defining an interval of about 7 cM for this new ARRP locus, between D2S148 and D2S161. Forty-four out of 47 additional ARRP families, tested with markers on 2q32, failed to show linkage, providing evidence of further genetic heterogeneity.
