(B) The left iris is damaged, and the pupils are unequal. If the left eye is illuminated, both pupils constrict less: there is a relative afferent pupillary defect on the left side. (A) If the right eye is illuminated, both pupils constrict normally. Therefore, it is advisable not to constrict the pupil below this range when performing the swinging-flashlight test.įig. For pupils with diameter of less than 3–4 mm, pupillary light responses are no longer linearly correlated with the light flux. Best results will be obtained if the illumination remains in a range that allows the pupil to respond linearly. If the light is too strong, the pupil will constrict vigorously until it reaches the mechanical endpoint and a subtle defect will be missed. It is convenient to start with a distance that allows the pupil to constrict by one-third of its initial diameter. By varying the distance from the eyes, the examiner can adjust the cornal illumination. A bright light, such as an indirect ophthalmoscope or a flashlight, is directed with an angle of about 45° to the optical axis from below to the upper peripheral retina. This test should be performed in a room as dark as possible in order to start with large pupils ( Wilhelm, 1998). The swinging-flashlight test looks for differences between the visual afferent pathways of the two eyes. If this is the case, a different approach is necessary. Preconditions are two pupils with the ability to react equally, i.e., no fixed or poorly reacting pupil, no marked anisocoria ( Fig. The swinging-flashlight test compares the direct light reactions of both eyes ( Levatin et al., 1973).

Brisk pupil reaction