Purchase this article with an account.
G Niemeyer, K Jost; Comparison Of Scotopic Threshold Response With Optic Nerve Response And Electrically Driven Retinal Field Potentials In Vitro . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1815.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To test similarities between the scotopic threshold response (STR) of the ERG and the optic nerve response(ONR) and to study the retinal response to antidromic stimulation of the optic nerve in the in vitro perfused mammalian eye. Methods: Arterially perfused cat eyes, enucleated under deep anesthesia and analgesia, were used to record the vitreo-scleral ERG and the ONR. We analyzed response/intensity series of b-wave, STR, and ONR in the range of threshold stimulus intensities in full dark adaptation. Changes in flow rate of perfusion were induced to observe effects on the light-evoked signals, and the changes following very dim background illumination were tested. - Additional experiments: The ERG reference electrode was moved on the slcera, the optic nerve was stimulated electrically (0.2-1 ms, 8-20V) to evoke retinal responses (also combined with photic stimulation), and TTX was injected into the optic nerve to block the ONR and optic disc . Results: The amplitude of the STR increased with moving the ERG-reference electrode toward the optic nerve. The ONR had a lower threshod than the STR . The ONR was always faster and maintained its negative polarity, whereas the ERG channel recorded at increasing intensities the b-wave (PII) that dominated the ERG above saturaturation of the STR. The latency of STR and ONR decreased simliarly with increasing stimulus intensity. The STR and the ONR were more sensitive than the PII to very dim backgrounds (room light below 0.1 lux). Increase in flow rate of perfusion enhanced STR and ONR amplitudes markedly while the PII was not affected. Antidromic electrical stimulation of the optic nerve elicited an STR-like retinal response, that could be shown to summate with the light-evoked STR. Conclusion: STR and ONR reveal similar features, including parappel changes during increase in perfusion flow. STR-like retinal responses could be elicited electrically. The data provide additional evidence for retinal ganglion cells as the common generator of both field potentials, validating the the STR’s clinical use in assessing inner retinal function.
This PDF is available to Subscribers Only