Rod-driven focal macular electroretinogram.
OBJECTIVE
To determine the stimulus conditions required to elicit rod-driven, focal macular electroretinograms (rod FMERGs).


METHODS
A blue (lambda(max)=470 nm) stimulus, 5 degrees in size, was imaged at a luminance of 1.5 cd/m(2) on different regions of the human retina. Electroretinograms (ERGs) elicited by this stimulus were recorded from the light- and dark-adapted retina of four subjects without any ophthalmological abnormalities. A subject with cone dystrophy was also tested by this method.


RESULTS
Stimulus luminance <==1.5 cd/m(2) did not elicit a response when it was imaged on the optic disc, but higher intensities elicited a small b-wave from stray light. When this stimulus was imaged on the macular area or the 15 degrees temporal retina, an ERG was elicited that had the shape of the full-field scotopic ERG. This stimulus with a luminance of 1.5 cd/m(2) did not elicit a response from stimulation of the macular area of a light-adapted retina but elicited a slow-rising positive b-wave after 30 minutes of dark adaptation. In a subject with cone dystrophy, focal rod response was elicited from the macula, despite no response under photopic conditions.


CONCLUSIONS
We conclude that this stimulus will elicit a response that is derived exclusively from rods and is a focal response with no contribution from stray light.
Choshi
Toshiharu
T
Department of Ophthalmology, Oita Medical University, Oita, Japan. choshi@oita-med.ac.jp
Matsumoto
Celso Soiti
CS
Nakatsuka
Kazuo
K
D000328:Adult; D003623:Dark Adaptation; D004596:Electroretinography / Q000379:methods*; D005260:Female; D006801:Humans; D008266:Macula Lutea / Q000502:physiology*; D008297:Male; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology; D012162:Retinal Degeneration / Q000503:physiopathology; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*