Function of Rods and Cones

Rods and cones are a vital part of the eye, helping define what we see. Here’s what you should know.
Crayons for rods and cones
1. There are three types of color-sensing cones, red, blue and green. If you are color blind one or more of these cells is missing or not working properly.

2. Men have a higher chance of being color blind than women. 1 out of 12 vs. 1 out of 255.

3. The most common type of color blindness is the disability to tell the difference between red and green.

4. The eye can distinguish between 500 shades of gray.

5. A healthy human eye can detect over 10 million different colors.

6. About 2% of women have a rare genetic mutation that gives them an extra retinal cone allowing them to see more than 100 million colors.

7. During a major depression people see less contrast, making colors appear duller.

8. All babies are color blind when they are born. Color vision begins to develop within a week after birth and by 6 months your baby can see every color you can.

9. Your eyes contain 7 million cones which help you see color and detail.

10. The stars and colors you see when you rub your eyes are call phosphenes.

11. There are 120 million light-sensing cells called rods which help you to see better in the dark.

12. Smoking reduces your night vision.

And these are just fun facts about eyes:

The Mayans believed that cross-eyes were attractive and would make efforts to ensure their children became cross-eyed.

Pirates used to wear a gold earring, believing it improved their sight. They also used eye patches to quickly adjust their eyes from above to below deck. When going below deck where it was dark, they flipped up the eye patch to see with the eye that had not be affected by light.

The phrase “it’s all fun and games until someone loses an eye” comes from Ancient Rome, as the only rule for their bloody wrestling matches was “no eye gouging.”

Susan DeRemerSusan DeRemer, CFRE
Vice President of Development
Discovery Eye Foundation

Rods and Cones Give Us Color, Detail and Night Vision
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