1. The human eye

2. What are the main parts of the human eye? Ciliary muscle Cornea Iris Lens Optic nerve Pupil Retina Sclera Vitreous humor Aqueous humor

3. Correction

4. Sclera ; iris ; pupil ; cornea

5. Sclera The sclera is the white of the eye. "Don't shoot until you see their scleras." Cornea The cornea is the clear bulging surface in front of the eye. It is the main refractive surface of the eye. Iris/Pupil Iris is heavily pigmented Pupil is the hole through which light passes Pupil diameter ranges from about 3-7 mm Eye color (brown, green, blue, etc.) depends on the amount and distribution of the pigment melanin

6. Human eye color charts

7. Lens ; ciliary muscles Transparent body enclosed in an elastic capsule Made up of proteins and water Gradient refractive index (1.38 - 1.40) Young person can change shape of the lens thanks to ciliary muscles Contraction of muscles causes lens to bulge At roughly age 50, the lens can no longer change shape : presbyopia Becomes more yellow with age: cataracts

8. Retina The light has to pass through many layers of cells before finally reaching the photoreceptors. The photoreceptors are where the light is absorbed and transformed into the electrochemical signals used by the nervous system. This change is called transduction. There are two types of receptors: the rods (rod- shaped) and the cones (cone-shaped). The rods enable us to see black and white; the cones enable us to see the colors. Three types of cones exist: cones that absorb long-wavelength light (red) cones that absorb middle-wavelength light (green) cones that absorb short-wavelength light (blue)

9. Rods and cones

12. Two kinds of lenses

13. Experiments

14. Method to determine the focal length

16. Defects of vision

18. Optical illusions