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Jorge Bohorquez, Jonathon Toft-Nielsen, Nilufer Yesilirmak, Vittorio Porciatti, Ozcan Ozdamar; Lower eyelid topography of PERG responses obtained at different pattern reversal rates. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):490.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the contributions of different inner retinal generators to the Transient and Steady-state pattern Electroretinogram (PERG), at different reversal rates.
Assuming that different PERG components have different dipole generators, the relative contribution of different generators can be derived by an array of spaced electrodes on the eye lid surface. PERG responses from normal eyes were acquired at four lower eyelid positions (reference electrode: other eye lower eye lid center) and three different reversal rates (1.86, 15.6 and 70.3 rps) to investigate the contributions of different inner retinal generators. A fast reversing (100µs) LED display was used for simultaneous and temporally accurate pattern reversal and improved response generation. Reference eye was occluded with an eye patch.
At low rates (1.86 rps) transient PERGs, obtained with conventional averaging, showed largest amplitudes at electrode positions located at low eyelid directly below pupil (-90deg) and towards lateral electrodes (+/- 45deg). At positions next to lateral canthus (0 deg), P50 was greatly reduced and N95 broadened significantly. At medium (mean 15.6 rps) and high (mean 70.3 rps) reversal rates, slightly jittered stimulations were used to acquire transient PERGs through deconvolution of the generated quasi steady-state responses. Transient responses obtained at 15.6 rps showed slightly smaller P50 and N95 amplitudes than that the 1.86 rps ones; the PERG below pupil presented also the maximum amplitude in the topography. At 70.3 rps, triphasic responses were observed but with strong negativity around 40 ms at all electrodes, including a significant activity in the electrode placed next to the lateral cantus.
Conclusions. The results show that primary PERG components (P50 and N95) are generated separately by different dipoles that adapt differently with reversal rate.
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