Detection of objects in the peripheral field of vision is enhanced by motion or intermittent presentation. A change in stimulus causes an alteration in the state of excitation which is more readily perceived than a continuous stimulus on the same retinal receptors.
In ordinary perimetry, test objects of various sizes are moved at a slow speed from outside into the field of vision, thus determining the border line of the field of perception. This method gives little or no quantitative information on sensitivity inside the stated boundaries, except when scotomata are encountered and a target ceases to be perceived.1,2
To obtain detailed information on sensitivity in various regions of the visual field, the method of absolute or differential threshold determination must be employed. Since this method is very time-consuming it is generally used only in basic studies with trained observers and is applied in clinical work only for special
WOLF E, McGOWAN BK. The Effect of Light-Time: Dark-Time Ratio and Luminance on Peripheral Sensitivity to Flicker. Arch Ophthalmol. 1963;69(2):241–250. doi:10.1001/archopht.1963.00960040247017
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