ELECTROPHYSIOLOGICAL EVALUATION OF VISUAL-LOSS IN MULLER CELL SHEEN DYSTROPHY

Aims-To describe the clinical picture and electrophysiological finding s in Muller cell sheen dystrophy, a recently reported retinal dystroph y. Method-A basic ophthalmological evaluation as well as recording of standard electro-oculography and electroretinography were performed in one patient at the onset of visual loss and after 1 year of follow up . Results-A 61 year old woman presented with visual loss in the right eye. Multiple folds at the level of the internal limiting membrane wer e seen at the posterior pole in both eyes. Macular oedema was present in the right eye. The visual acuity of the right eye was 6/30 and of t he left 6/9. A paracentral scotoma was found in the right eye. Electro -oculographic examination of both eyes gave normal results. Electroret inography (ERG) revealed reduced b-wave and flicker amplitudes in the right eye; these potentials were normal for the left eye. The ON respo nse in the right eye was reduced and delayed; it was normal in the lef t eye. A further loss of visual function was noted 1 year later in the right eye, but the ophthalmoscopic findings were unchanged. The ERG o f the right eye had a negative waveform when dark adapted. Light adapt ed responses showed an unusual delayed b-wave, broad and delayed ON an d OFF responses and a missing flicker response, suggesting a Muller ce ll dysfunction. Light adapted responses were slightly reduced in the l eft eye. Conclusions-Electrophysiological data indicate Muller cell dy sfunction as a background of functional loss in Muller cell sheen dyst rophy. This is in agreement with previously reported histological find ings in this disorder.