Step 1: Start from the outside surface of the eye.
Light first meets the eye at the cornea, the curved transparent window at the very front.
Step 2: Look at what controls how much light gets in next.
Right after the cornea, light passes through an opening called the pupil, whose size the iris adjusts depending on the brightness around.
Step 3: Follow the light to the focusing element.
Behind the pupil sits the crystalline lens, which fine tunes its shape to bring the light to a sharp focus.
Step 4: Reach the screen at the back.
Finally the focused light lands on the retina, the light sensitive layer at the back of the eye that turns it into signals for the brain, giving the order cornea, pupil, lens, retina.
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