Those of us who have to make many examinations of neurologic patients have been confronted frequently with the great difficulty of obtaining satisfactory tests of the pupil light reflex. This is especially true when, for purposes of cerebral localization, it is desired to ascertain whether or not Wernicke's symptom (the hemianopic pupil inaction sign) is present. For ordinary purposes alternately covering and uncovering the eye with the hand permitting its exposure to the light of a candle, lamp or window is all that is necessary, but in those cases of very sluggish or very contracted pupils, such as are frequently observed in cerebral or spinal disease, it is essential to concentrate the light in order to ascertain whether the reflex is present or absent.
In order to make the test for Wernicke's hemianopic pupillary inaction symptom light can not be employed in the ordinary manner, as it is impossible to
VEASEY CA. AN INSTRUMENT FOR TESTING THE LIGHT-REFLEX OF THE PUPIL.. JAMA. 1907;XLIX(16):1362. doi:10.1001/jama.1907.25320160040003a