Assessment of the dark-adaptation time required for recovery of electroretinographic responses in dogs after fundus photography and indirect ophthalmoscopy.
OBJECTIVE
To investigate the duration of dark-adaptation time required for recovery of electroretinographic responses after fundus photography or indirect ophthalmoscopy in dogs.


METHODS
6 dogs.


METHODS
Initially, scotopic-intensity series of electroretinograms (ERGs) were recorded after 20 minutes of dark adaptation. The fundus of the left eye of each dog was photographed (n = 10) or examined via indirect ophthalmoscopy for 5 minutes with moderate- (117 candela [cd]/m2) or bright-intensity (1,693 cd/m2) light; ERGs were repeated after a further 20 or 60 minutes of dark adaptation (6 procedures/dog).


RESULTS
Following 20 minutes of dark adaptation after fundus photography, the b- and a-wave amplitudes were reduced in response to brighter stimuli, compared with pretest ERGs; after 60 minutes of dark adaptation, ERG amplitudes had recovered. Following 20 minutes of dark adaptation after indirect ophthalmoscopy (moderate-intensity light), significantly lower b-wave amplitudes were recorded in response to 2 of the brighter flash stimuli, compared with pretest ERGs; after 60 minutes of dark adaptation, ERG amplitudes had recovered. Following 20 minutes of dark adaptation after indirect ophthalmoscopy (bright-intensity light), all ERG amplitudes were significantly decreased and implicit times were significantly decreased at several flash intensities, compared with pretest ERGs; after 60 minutes of dark adaptation, ERG amplitudes and implicit times had returned to initial values, except for b-wave amplitudes recorded in response to dimmer stimuli.


CONCLUSIONS
Results suggest that at least 60 minutes of dark adaptation should be allowed before ERGs are performed in dogs after fundus photography or indirect ophthalmoscopy.
Tuntivanich
Nalinee
N
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824-1314, USA.
Mentzer
A Lexi
AL
Eifler
Danielle M
DM
Montiani-Ferreira
Fabiano
F
Forcier
Janice Q
JQ
Johnson
Cheri A
CA
Petersen-Jones
Simon M
SM
D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D004285:Dogs / Q000502:physiology*; D004596:Electroretinography; D005451:Fluorescein Angiography / Q000009:adverse effects*; D009887:Ophthalmoscopy / Q000009:adverse effects*; D020127:Recovery of Function / Q000502:physiology*; D012160:Retina / Q000502:physiology*; D013997:Time Factors