What does 'pupillary reflex' refer to?

The term 'pupillary reflex' refers to the eye's ability to respond to changes in light intensity, specifically the contraction and dilation of the pupil in response to bright and dim light. This reflex helps to protect the retina from excessive light exposure and aids in optimizing vision under varying lighting conditions. The pupil constricts when exposed to bright light to reduce the amount of light entering the eye, while it dilates in low light to allow more light to enter, improving visibility.

Tracking moving objects relates to visual tracking skills but is not directly tied to the reflexive actions of the pupil based on light. Eye color changes in different lighting pertain to the perception of color and not the reflex mechanism itself. Eye strain from focusing on something for an extended period does not involve the automatic responses of the pupil but rather pertains to discomfort and fatigue in the eyes due to prolonged effort. Therefore, the responsiveness of the pupil to variations in light correctly defines the pupillary reflex.