Which test compares both direct and consensual pupillary responses?

The swinging flashlight test is a specific examination used to assess the function of both the direct and consensual pupillary responses. During this test, a light source is alternately directed into each eye while observing the pupil's reaction. When light enters one eye, that pupil should constrict (the direct response), while the opposite pupil should also constrict in response to the light due to the consensual reflex. This test is particularly useful for detecting afferent pupillary defects, as it allows for comparison between the pupils in response to the light stimulus. By observing the simultaneous responses, clinicians can gain insights into potential neurological issues affecting the optic nerve or the pathways controlling pupil response.

In contrast, the other options listed do not assess pupillary reactions. The applanation test measures intraocular pressure, the tonometer test is specifically for determining eye pressure, and the visual acuity test evaluates clarity of vision. Thus, they do not provide the same functional assessment of pupillary response that the swinging flashlight test offers.