Biology / Unit 12 Bio 2905 short lesson, about 20 seconds
Eye Anatomy: Cornea, Lens, Iris
Captions available
The idea
Light entering the eye is bent by the cornea and lens to focus on the retina, while the iris adjusts pupil size to regulate light entering.
In practice
A lens that loses flexibility with age causes presbyopia, a farsightedness from focus falling behind the retina.
Where people slip
Myopia and hyperopia both involve where the image focuses relative to the retina, but in opposite directions.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Biology