Night vision, also known as scotopic vision, is our natural ability to see in darkness. In a dark room at night, your eyes seek to gather as much light as possible to transmit images to your brain. Your eyes achieve this by dilating your pupils, allowing more light and shapes to enter.
HOW DOES NIGHT VISION WORK?
Want to test this? Stand in front of a mirror in a dark room for a minute. Make sure your eyes are completely closed. Then, with your eyes still closed, turn on the light. Facing the mirror, open your eyes, and you'll see your pupils contract. This is because in a brighter environment, your pupils have enough light for your eyes to see, so they don't need to be as large as in the darkness.
But it's not just the pupils that enable you to see in the dark. For that, you need to look at the microscopic cells at the back of your eyes. There are millions of rod and cone-shaped cells on the retina of each eye, and without them, we wouldn't be able to see.
Cones record bright lights, colors, and fine details, while rods help you see in darker environments because they are more sensitive to light. However, rods do not process colors – that's why in the dark, you struggle to distinguish colors.
DO HUMANS HAVE GOOD NIGHT VISION?
Compared to animals, humans do not have the best night vision. Our eyes take much longer to adapt to a dark environment, approximately 40 minutes!
This is because humans don't need to see in the dark as we are typically asleep at night and awake during the day. Nocturnal animals that spend a lot of time in darkness tend to have better night vision. Have you ever noticed that the eyes of cats and dogs glow at night? That's because they have a reflective layer behind their retina that enhances their night vision.
EYE CONDITIONS THAT CAN AFFECT NIGHT VISION.
Some eye infections can make night vision difficult, a symptom called nyctalopia (or night blindness).
Different levels of night blindness can be caused by:
- Retinitis pigmentosa
- Imbalances in glucose or vitamin A