Abstract
Purpose: :
To study the properties of the photopic negative response (PhNR) of focal macular electroretinograms (fmERGs) elicited by different stimulus intensities and stimulus durations in monkeys.
Methods: :
The focal macular PhNRs were recorded from five rhesus monkeys using a modified infrared fundus camera, in which a red LED (=627 nm) stimulus spot and blue LED (=450 nm) background illumination were incorporated. The stimulus intensity and duration were changed and presented on a blue background of 3.7 log scot-td. The effect of stray-light on the focal ERGs was studied by recording focal ERGs from a retinal site damaged by focal laser coagulation.
Results: :
After the photocoagulation, "focal" ERGs were obtained with red intensities <3.5 log phot-td (55 cd/m2) on a steady blue background of 3.7 log scot-td. The amplitude of focal macular PhNR increased with increasing stimulus intensities, and was 5.9±0.5 µV for a 15 degree stimulus spot of 10 msec duration at 55 cd/m2. The amplitude of focal macular PhNR was dependent on the stimulus duration, and was larger for longer stimulus durations of 30-150 msec.
Conclusions: :
It is possible to record focal macular PhNRs from the primate retina with red stimulus spot on a blue background. Focal macular PhNRs can be used to study the inner retinal function of localized areas in normal and diseased retinas.
Keywords: electroretinography: non-clinical • electrophysiology: non-clinical • ganglion cells