The Human Eye Comparing human eye to camera

The Human Eye Comparing human eye to camera Hyperopia, Presbyopia & Myopia

Components of the Eye Iris Pupil Eye Iris (coloured Camera equivalent Function Diaphragm Controls amount of light Aperture Where light enters the eye part) Pupil (hole in iris)

Components of the Eye Iris Pupil Cornea Eye Lens Camera equivalent Cornea & Converging lens Lens combo Function Refraction of light (mostly in cornea) Focuses light

Components of the Eye Retina Iris Pupil Cornea Lens Eye Camera equivalent Function Retina Film or digital sensor Light sensitive cells convert light signals to electrical signals

Components of the Eye Retina Iris Pupil Optic Nerve Cornea Lens Eye Optic nerve Camera equivalent Function Electrical signals are passed through to the brain

Components of the Eye Image formed on retina will be smaller & inverted. You “see” with your brain Your brain will “flip” the image

Eye Accommodation Ciliary muscles can change the shape of the lens slightly to accommodate focusing on distant & nearby objects.

Hyperopia (Far-sightedness) Problem focusing on nearby objects. Due to either: a) Distance between lens & retina are too small b) Focusing power of cornea-lens combination is too weak light is focused behind the retina Solution: Corrective converging lens (or positive meniscus)

Presbyopia Also problem on seeing nearby objects. HOWEVER, this is due to aging because lens lose their elasticity. Solution: Corrective converging lens.

Myopia (Near-sightedness) Problem focusing on distant objects. Due to either: a) Distance between lens & retina are too large b) Focusing power of cornea-lens combination is too strong light is focused in front of retina Solution: Corrective diverging lens (or negative meniscus)