wˈɪt ɛksplˈeɪnz ðætðə pjˈuːpɪlɚɹi lˈaɪt ɹˈiːflɛks ɪz ðə kəntɹˈækʃənz ænd ɹˌiːsˈaɪzɪŋ ʌvðə pjˈuːpəl ɪn dˈɪfɹənt ɪntˈɛnsᵻɾiz ʌv lˈaɪt.
Whytt explains that the pupillary light reflex is the contractions and re-sizing of the pupil in different intensities of light.