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[Foveal cone dystrophy: diagnostic ranking of the multifocal electroretinogram]
1Augenklinik für Schielbehandlung und Neuroophthalmologie der Universitäts-Augenklinik, Giessen.
Background:
In case of visual loss without morphologic pathology differentiation between a functional visual loss and a retinal disorder may be difficult.
Patients And Methods:
We report on two women, aged 33 and 44, who were complaining of a progressive visual loss occurring over the past several weeks to months. They were referred to our department with the presumed diagnosis of functional visual loss. Biomicroscopy of the anterior and posterior segments, perimetry (Goldmann), colour (FM-100-Hue-Test) and stereopsis testing (Lang-Stereotest), fluorescein angiography (FLAG) and electrophysiological testing (P-ERG, VECP, EOG, multifocal electroretinography [mfERG]) were performed.
Results:
Visual acuity was 0.16 OU and 0.25 OU respectively. A small relative central scotoma (I/1) was detected by dynamic perimetry. Colour vision, random-dot stereopsis and the results of electrophysiological testing except multifocal electroretinography (mfERG) were normal. The mfERG was able to detect a cone dysfunction which was related to the fovea.
Conclusion:
In case of visual loss of unknown etiology electrophysiological testing is indicated. The mfERG as an objective diagnostic method is able to detect a foveal cone dystrophy.