Human eye
Beginner
Lens focuses light onto the retina.
Cornea and lens focus light onto the retina; the ciliary muscle changes the lens shape (accommodation). Near point is 25 cm and far point infinity for normal vision.
Rods work in dim light and cones for colour.
The retinal image is inverted.
In more detail
The human eye focuses light with the cornea and the lens onto the retina. The ciliary muscles change the lens shape to focus on near and far objects.
Real-world uses
- Eye models are used in ophthalmology and optics teaching.
- Camera design takes inspiration from the eye.
- The eye focuses light through the cornea and lens onto the retina, where light-sensitive cells send signals to the brain.
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Frequently asked questions
What does the iris do?
It controls the amount of light entering the eye, like a camera aperture.
Why does the lens harden with age?
It loses flexibility, which makes focusing on near objects harder.
What does the eye lens do?
It changes shape to adjust its focal length, which lets you focus on near and distant objects.
Related topics in Optics
Power of a lens · Combination of lenses · Lens aberrations · Defects of vision · Simple microscope · Compound microscope