1 / 54

Understanding Vision: Light, Shadows, and Sight Defects

Discover how light enters the eyes, the role of shadows, and the two types of sight defects - farsightedness and nearsightedness. Learn about corrections and the effects of water and color blindness on vision.

lfulbright
Download Presentation

Understanding Vision: Light, Shadows, and Sight Defects

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Vision

  2. The only thing you can see is light. In order to see light, the light must enter your eyes. If no light enters your eyes, you will see nothing - - only darkness.

  3. What can you see in a dark room? Nothing!

  4. Shadows

  5. Shadows are black because the body is blocking all the light. Seeing a shadow is seeing the absence of light.

  6. The eye adapts to varying light conditions. This is similar to the shutter of a camera.

  7. The Eye

  8. The eye “sees” an object when bundles of diverging rays from each point on the object enter the pupil and are focused to an image on the retina.

  9. Two types of “sightedness” Farsighted Nearsighted

  10. Farsightedness • Easier to see far away things. • The eye’s lens is too weak. • The image would focus past the retina (back of the eye).

  11. Correction (Farsighted) • A convergent lens helps the eye out by focusing the light a bit before it enters the eye.

  12. Nearsightedness • Easier to see close up • Lens is too strong. • The image focuses before the retina (back of the eye).

  13. Correction (nearsighted) • A divergent lens is used to spread the light out a bit before it enters the eye

  14. A person who sees more clearly under water than in air without eyeglasses is… 1) Nearsighted 2) farsighted 3) neither

  15. Nearsighted! The speed of light in water is less than in air, so the change in speed is less as light goes from water to your eye. Less refraction occurs. This makes all people more farsighted under water, which is advantageous if you’re nearsighted. If you’re very nearsighted, the image may fall on your retina and you’ll see as clearly under water as a person with normal vision who wears an air-enclosed mask.

  16. Color Blindness - What number do you see? 29 45 56 6 8

  17. Blind Spot 0 X Stare at the O with only your right eye.

  18. Square A and B are the same shade of grey

  19. Stare at the black dot….

More Related