Rods and Cones: What Are They?


Sight is a complicated process with a lot of components. One vital part of the eye is the light-sensitive layer of tissue called the retina, which contains photoreceptor cells. Photoreceptors convert light into signals for your brain. The two main kinds are rods and cones.


Rods are sensitive to light and dark, and they help us as we’re in low-light conditions. Unfortunately, in these dim areas, we cannot see colors well since rods are not sensitive to colors. There are about 120 of these cells in the retina, and you have them more in your peripheral vision than the center of your vision. That means that if you are straining to see something at night, you might have better luck looking at it out of the corner of your eye rather than trying to see it straight on. You should also know that it takes 7-10 minutes for your rods to activate. That is why when you turn off the lights, it takes some time for your eyes to adjust.


Cones are the sensitive photoreceptors that help us see both colors and fine details. Cones are most sensitive to one of the three primary colors (red, yellow, or blue), and people who do not have certain cones or who have some weak cones may be color blind, meaning that they can’t see certain colors. (More men than women tend to be color blind.) There are about 6 million cones in the retina, and they only work in bright light.

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