Purchase this article with an account.
Marten Erik Brelen, Danny Ng, Wong Ying Yip, Christopher Kai-Shun Leung, Chi Pui Calvin Pang; A novel pre-amplified ERG electrode which improves the quality of recorded signals. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5767.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To compare the quality of recorded signals using a standard/passive ERG electrode to a custom built active electrode. The active electrode has an amplifier attached to the electrode transducer which, through impedance transformation, reduces the amount of electrical noise from the electrode cable.
A unity gain buffer amplifier was constructed using off the shelf operational amplifiers (Analaog Devices ADA-4899). The amplifier was powered using standard 9V batteries. A loop of gold wire was used as the transducer. The wire was cut as short as possible (less than 10mm) and soldered to the input of the customized amplifier. All electronic components were hermetically sealed in epoxy. Six rodents were used to test the electrode. In each experiment one eye had the active electrode applied and the fellow eye had the passive electrode. Both the active and passive electrodes were connected to the Espion E3 (Diagnosys) amplifier. The animal light stimulation dome of the Espion E3 was used. Scotopic and photopic ERG responses, scotopic threshold response (STR) and photpic negative response (PhNR) were recorded.
The background noise of the passive electrode was significantly higher than the active electrode (3.803 μV/√Hz active and 4.394 μV/√Hz passive electrode). Signal amplitudes were consistently much greater for a (-52.4+-32.6nV active and -30.72+-22.45nV passive) and b (232.5+-38.6nV active and 141.6+-78nV passive) wave amplitudes in the active vs passive electrode. The negative component of the scotopic threshold response could be seen at the lowest stimulation strength of -4.3log cd.s.m-2 in all the rodents but the passive electrodes required between -3.75 and -3.25log cd.s.m-2 before STR is seen. The reproducibility of the signals were far greater in the active electrode as evidenced by lower standard deviations of the a and b wave peaks in the active vs passive electrode. The PhNR amplitudes were also greater in the active vs passive electrode (-152.4+-13.9nV active and -100.0+-157.31nV .passive). Early receptor potentials (ERP) could be seen at very low light stimulation strengths (-0.5log cd.s.m-2) and were peak-to-peak 10µV in amplitude which is far greater than that reported in the literature.
The active ERG electrode produces lower ambient noise, greater SNR ratio, greater reproducibility of recordings and allows responses to be recorded at lower stimulation strengths.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
This PDF is available to Subscribers Only