Acute effects of sildenafil on the electroretinogram and multifocal electroretinogram.
OBJECTIVE
To evaluate the acute effects of sildenafil (Viagra; Pfizer, Inc, New York, New York) on the electroretinogram and multifocal electroretinogram.


METHODS
Eighteen healthy individuals (ages 21-49 years) were studied; 14 were given 200 mg sildenafil orally and four were given only water. All subjects were tested before sildenafil and 1 hour after sildenafil (or water) with a desaturated Panel D-15 color test, a full-field standard electroretinogram, and a multifocal electroretinogram using the VERIS system; five subjects were also tested 5 hours after sildenafil.


RESULTS
Responses from the subjects who received sildenafil were compared with those from the control subjects. At 1 hour after sildenafil, photopic single-flash waveforms were attenuated by 9% and scotopic maximal response amplitudes were increased slightly. Photopic and 30-Hz flicker electroretinogram responses were delayed; multifocal electroretinogram waveforms were delayed (5%-9%) and attenuated (14%-22%) across the posterior pole. These changes did not resolve by 5 hours. Nine of the subjects who had received sildenafil (64%) reported visual or systemic symptoms, including one who reported bluish vision. Ten of those subjects (71%) showed a slight increase in color test errors 1 hour after sildenafil.


CONCLUSIONS
For at least 5 hours after taking 200 mg of sildenafil, cone function was slightly depressed in the macula and periphery, as measured by full-field electroretinogram and multifocal electroretinogram recordings. However, the affected electroretinogram and multifocal electroretinogram parameters still remained within normal limits.
Luu
J K
JK
Medical Center, Stanford University, Stanford, CA 94305, USA.
Chappelow
A V
AV
McCulley
T J
TJ
Marmor
M F
MF
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000328:Adult; D003118:Color Perception / Q000187:drug effects / Q000502:physiology; D004596:Electroretinography / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010775:Photic Stimulation; D010879:Piperazines / Q000494:pharmacology*; D011687:Purines; D017949:Retinal Cone Photoreceptor Cells / Q000187:drug effects / Q000502:physiology; D000068677:Sildenafil Citrate; D013450:Sulfones; D013997:Time Factors
D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; D015106:3',5'-Cyclic-GMP Phosphodiesterases