Home▸Neuroscience & Biophysics▸The Pupillary Light Reflex: How Eyes Auto-Adjust to Brightness

👁️ The Pupillary Light Reflex: How Eyes Auto-Adjust to Brightness

Explore the pupillary light reflex, the automatic neural circuit that adjusts pupil size in response to brightness, from retinal photoreceptors through the midbrain to the iris muscles.

Neuroscience & Biophysics3DModerate60 FPS

This simulation demonstrates how the pupillary light reflex pathway converts a change in light intensity into a measurable change in pupil diameter through the retina, midbrain, and iris muscles.

🔬 What It Demonstrates

This simulation demonstrates how the pupillary light reflex pathway converts a change in light intensity into a measurable change in pupil diameter through the retina, midbrain, and iris muscles.

🎮 How to Use

Adjust the light intensity and watch how the pupil size responds in real time, and try toggling single-eye illumination to see the consensual reflex in action.

💡 Did You Know?

The pupillary light reflex is so fast and involuntary that it still functions in unconscious patients, which is why it is used as a bedside indicator of brainstem health.

⚙ Under the hood

Explore the pupillary light reflex, the automatic neural circuit that adjusts pupil size in response to brightness, from retinal photoreceptors through the midbrain to the iris muscles.

neurosciencephysiologyreflexvisionpupilbrainstemanatomybiology

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install