gms | German Medical Science

102. Jahrestagung der DOG

Deutsche Ophthalmologische Gesellschaft e. V.

23. bis 26.09.2004, Berlin

Assessment of rod vision in hereditary retinopathies

Meeting Abstract

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  • corresponding author A. V. Cideciyan - Scheie Eye Institute, University of Pennsylvania, Philadelphia, USA

Evidenzbasierte Medizin - Anspruch und Wirklichkeit. 102. Jahrestagung der Deutschen Ophthalmologischen Gesellschaft. Berlin, 23.-26.09.2004. Düsseldorf, Köln: German Medical Science; 2004. Doc04dogSO.07.06

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Veröffentlicht: 22. September 2004

© 2004 Cideciyan.
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Many inherited retinopathies exhibit dysfunction and/or degeneration of the rod photoreceptors either primarily due to mutations in genes expressed in rods or secondarily due to mutations in genes expressed in the RPE. Selected molecular defects will be used to demonstrate the isolation of rod system dysfunction from that of cones in human patients and comparisons will be made with results in animal models.


Electrophysiological methods include dark- and light-adapted ERG photoresponses analyzed with a model of phototransduction activation. Psychophysical methods include dark-adapted two-color perimetry, and bleaching adaptation studies. Dark-adapted transient pupillary light reflex is used to probe transmission of rod activity to higher visual centers. In vivo microstructure of the retina is assessed with optical coherence tomography. Accumulation of lipofuscin is quantified with autofluorescence imaging.


Rhodopsin is expressed exclusively in rods and mutations in the rhodopsin gene cause two classes of disease expression in patients with autosomal dominant retinitis pigmentosa: Class A mutants lead to severely abnormal rod function across the retina early in life, whereas Class B mutants are compatible with normal rods in adult life but there are abnormalities in dark adaptation kinetics. ABCA4 gene encodes for ABCR which is expressed in rods and cones. Mutations in ABCA4 gene cause a wide spectrum of autosomal recessive human disease. Colocalized measures of rod dysfunction, dark adaptation and lipofuscin accumulation allow the definition of the stages of human disease progression through a single sequence. RPE65 is involved in the retinoid cycle and mutations in the RPE65 gene cause severely abnormal photoreceptor function which is detectable with appropriate stimulus conditions. The patterns of rod dysfunction in naturally-occurring and genetically-engineered canine, porcine and rodent models of these human diseases can be similar or notably different.


Rod system dysfunction as either a primary or secondary consequence of the underlying molecular defect can be quantitatively assessed in human diseases, and the results used not only to understand human disease mechanisms and to develop outcome measures, but also to determine the relevance of available animal models that are key to pre-clinical trials of therapy.