1. Reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller
   - light reflex, miosis, myosis

Derived forms: pupillary reflexes

Type of: inborn reflex, innate reflex, instinctive reflex, physiological reaction, reflex, reflex action, reflex response, unconditioned reflex

Encyclopedia: Pupillary reflex

• isthmus
• Isthmus of Corinth
• Isthmus of Darien
• Isthmus of Kra
• Isthmus of Panama
• Isthmus of Suez
• Isthmus of Tehuantepec
• Istiophoridae
• Istiophorus
• Istiophorus albicans
• Isuprel
• Isuridae
• Isurus
• Isurus glaucus
• Isurus oxyrhincus
• Isurus paucus
• Isère
• Isère River
• it
• it never rains but it pours
• it'd
• it'll
• itaconic acid
• Italia
• Italian