1. UNDERSTANDING HOW YOU SEE http://www.youtube.com/watch?v=gvozcv8pS3c

2. HOW YOUR EYES SEE Located in the back of the eye, the retina contains FOUR different kinds of light sensitive cells. RODS, and THREE different types of CONES. CONES are color-sensitive cells, most of which can be found in a tiny region called, THE FOVEA. The fovea is responsible for color, sharpness, and spatial sensitivity.

3. HOW YOUR EYES SEE CONT. Cones only have the ability to detect light that strike them straight on. This means that only well-focused light can activate them. Since the Fovea is so small, only a tiny bit of your field of is in focus.

4. DEFENITIONS CORNEA: the transparent part of the coat of the eyeball that covers the iris and pupil and admits light to the interior. LENS: biconvex transparent body situated behind the iris in the eye; its role (along with the cornea) is to focuses light on the retina IRIS: the contractile, circular diaphragm forming the colored portion of the eye and containing a circular opening, the pupil, in its center.

5. DEFENITIONS CONT. RETINA:The layer at the back of the eye ball, containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve. FOVEA: part of the eye, located in the center of the macula region of the retina. The fovea is responsible for sharp central vision (also called foveal vision), which is necessary in humans for reading, driving, and any activity where visual detail is of primary importance. THE OPTIC NERVE: The optic nerve, also known as cranial nerve 2, transmits visual information from the retina to the brain.

6. FOVEAL VISION / CONES LISTEN FOR INSTRUCTIONS FOR THE EYE TEST! The focused area is the extent of your foveal vision. BECAUSE your eyes only respond to light coming from a single angle, CONES are not very light sensitive, and as light levels decrease, colors become muted, and the RODS in your eyes begin to take over.

7. RODS / PERIPHERAL VISION Rods cover about 98 to 99 percent of the retina. They are triggered by light coming in at any angle, which makes them incredibly sensitive to light. A rod that has been given time to adapt to the dark, has the ability to see a lit candle from up to 17 miles away! Rods are what we consider to be PERIPHERAL VISION. Peripheral vision is not sharp, BUT it is great for seeing dim objects in low light.

8. RODS / PERIPHERAL VISION CONT. Rod vision (peripheral vision) can al so come in handy when walking in the dark. If walking outside in the dark, keep your eyes focused directly ahead of you, and don’t move them while you walk. You will probably find that your peripheral vision reveals a tremendous amount of detail on the path in front of you. This technique will help you more than using a flash light, because the flash light wipes out your low light vision.

9. LETS REVIEW Eye ball contains the retina four different kinds of cones Cornea Lens Iris Retina Fovea And Optic Nerve