Gyrate atrophy ofthechoroid andretina: ERG ofthe neural retina andthepigment epithelium

performedwithadispos-ablecornealwickelectrodedescribedbySievingetal'4andslightlymodifiedbyus. Therecordingmethodis described in detail elsewhere.8 Asnolid speculum wasused, the subject wasable toblink. Theelectrodewasplacedonthesurfaceofthe topically anaesthetisedeye(0 4%oxybupro-caine hydrochloride, Oftan Obucain), where itsettled above the margin ofthe lower lid. Theelectrodeis welltolerated, andoccasionalblink-ingkeepsit moist.Beckmann's Ag-AgCl disk electrodes wereusedas ground(on the forehead) andreference(on the ipsilateral temple) electrodes. Thepreparationsfortherecordingwereperformedin