noun
pupillary reflex
A biological/medical term for the automatic constriction or dilation of the pupil in response to light or focus changes.
医師は瞳孔反射を調べて、神経系の状態を確認した。
The doctor checked the pupillary reflex to assess the condition of the nervous system.
Compound of 瞳孔 (どうこう, 'pupil') and 反射 (はんしゃ, 'reflex').