Electroretinographic wet electrode

This paper presents the first systematic characterisation of a new electroretinographic (ERG) electrode, recently described. The new ‘wet’ electrode uses a conducting liquid as a distributed electrical interface between the eye and a solid electronic conductor; the latter detects the ERG potential without any direct contact with the ocular surface. This technique avoids the contact-induced discomfort of both corneal and conjunctival standard electrodes. The wet electrode was tested on ten volunteers, in comparison with a conjunctival electrode (HK loop), as the most comfortable standard. It was also compared with a cutaneous (cup) electrode, which is even more comfortable, although not standard. Results showed the efficacy of the wet electrode for detecting morphologically accurate ERG responses, with amplitudes respectively analogous and higher of those measured by the conjunctival and cutaneous electrodes. Properties of wet electrodes include: no solid interface with the eye, no need for anaesthesia, intrinsic safety, mechanical and electrical stability against ocular movements, tolerance to misplacements and immunity to lacrimation. As a drawback, the liquid can still be a source of discomfort for some patients and it requires care against possible leakage. All these features suggest a possible use of wet electrodes as an additional tool for ERG procedures, although limited to tests of short duration.