Pupil Gauge Penlight
A pupil gauge is designed to assess pupillary response using the pupillary diameter guide printed on its side.
The pupil is the dark circle in the center of the eye through which vision is achieved.
Pupillary response is an involuntary physiological reflex in which the size of the pupil of the eye changes in response to stimuli such as light, cognitive load, memory formation/retrieval, arousal, and certain drugs.
When bright light is shone on the eye, light-sensitive cells in the retina will send signals to the oculomotor nerve. When this muscle contracts, it reduces the size of the pupil to reduce the amount of light entering the eye, just like the aperture of a camera.
Pupils dilate and contract together, even if light only enters one eye. Testing this light reflex provides a useful diagnostic tool for the sensory and motor functions of the eye as well as brain stem function.
Does not include batteries. Requires 2 AAA batteries to operate.