Did you ever wonder how we see at night? Our vision might not be as good as a cat’s eyes in the dark, but our eyes are specially designed to adjust to different levels of light to see in a variety of lighting situations.
First: How Do Human Eyes See?
To understand how we can focus and see at night, it’s essential to know how we see at all.
When you look at a picture, the first thing to happen is light passes through your cornea. The cornea is a transparent front layer at the front of your eye. Light passes through this and then through an opening in your eye called your pupil. Your pupil is the black round dot at the center of your eye.
Fun fact about your pupil- it’s black because the light striking it is completely absorbed into the deeper part of the eye.
Your iris is the colorful part around the pupil. This controls how much light is let into your eyes. Your pupil shrinks in bright light because less surface area is required to let light in. In low light conditions, your pupil expands to allow as much light as possible.
Then the light passes into the lens, which works with the cornea to focus light best on the next part of your eye, your retina. The retina contains photoreceptors that turn the light into electrical signals. The photoreceptors are referred to as cones and rods.
The optic nerve then acts as a superhighway to get those electrical signals to your brain. Your brain then interprets those signals into images.
How Do Human Eyes See At Night?
When you’re in the dark, the first thing your eyes do to see better is open your pupils up wide. This way, they can gather as much light as possible to send back to your cones and rods.
Cones are great for bright lights and colors, and fine details. However, they don’t do so great in the dark. This is where your rods take over. Rods are what you use for peripheral vision and low-level light. However, rods are color-blind. They can’t process color, which is why our attention to detail and color in the dark is so low.
The Bottom Line
When you’re in the dark, trying to see, your eye is going through this process:
- First, the pupil grows, letting as much light in as is available.
- Next, whatever light is there passes through the cornea, pupil, and lens to your retina.
- Then, the rods in your retina absorb that light, converting the light into electrical signals.
- Finally, the electrical signals pass along your optic nerve to your brain, which translates the electrical signals into images.
Our eyes are amazing machines that can accomplish this process thousands of times every second so that we can see.
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