Abstract
Purpose:
To study the effect of pupil size on the 28.3-Hz flicker electroretinograms (ERGs) recorded by RETeval, a new mydriasis-free full-field flicker ERG system.
Methods:
Ten healthy subjects were studied. The RETeval system is designed to deliver a constant flash retinal illuminance by adjusting the flash luminance to compensate for changes in the pupil size. Three experiments were performed. First, RETeval flicker ERGs were recorded every three minutes after the instillation of mydriatics; second, RETeval flicker ERGs were recorded while the patient wore soft contact lenses with two different artificial pupil sizes; and third, flicker ERGs were recorded with a conventional ERG system while wearing soft contact lenses with two different size of artificial pupils and after adjusting the flash luminance to compensate for the difference in the pupil size.
Results:
After the instillation of mydriatics, the amplitude of RETeval flicker ERGs did not change significantly, but the implicit times were significantly prolonged. Results of second experiment showed that the implicit times of RETeval flicker ERGs were significantly longer with larger artificial pupils. Results of third experiment showed that the amplitudes of the flicker ERGs were significantly larger for the small artificial pupils than for the large artificial pupils recorded with a conventional ERG system. However, the implicit times were not significantly different between two artificial pupils.
Conclusions:
These results suggested that not only the changes in the pupil size, but also other factors should be considered when trying to obtain exactly the same flicker ERGs under naturally constricting pupils.<br />