It happens every year – the days get shorter and the nights get longer this time of year, which means in North America there are more hours of darkness than there are daylight hours. Many people feel like their night vision isn’t as good as it should be, which makes viewing Christmas lights hard on the eyes and driving after dark difficult and even dangerous. Here’s what you need to know about night vision.
Many animals see better at night than humans do as a result of their biological make up. Animals have larger eyeballs, lenses, and optical apertures than humans, and more rods and cones than humans. The optical apertures in animals allow their pupils to expand up to the physical limitation of their eyeballs! Some animals, especially nocturnal ones, also have a tissue layer at the back of the eye called the tapetum lucidum which reflects light back through the retina, increasing the amount of light used to see with.
The photoreceptor cells in the human eye contain proteins: photopsin in color vision cells and rhodopsin in night vision cells, as well as small photoreceptor molecules called retinal. Retinal undergoes irreversible changes when exposed to light, which result in changes in the shape of the protein around the retinal, which cause the physiological process of vision.
In order to regenerate, which needs to happen when changes in light and dark occur, retinal must disperse from the vision cells, out of the eye and down to the liver. Once retinal is regenerated, it can circulate back to the eye. It takes about 45 minutes for retinal to completely regenerate and recharge all of the photoreceptors.
This recharging process is why you can see better in the dark when you wake up in the middle of the night than if you walk into a room and turn off the light. In the middle of the night, your photoreceptors have already been recharged but when you switch off a light, they haven’t had time to fully recharge before you are trying to see in the dark. When your photoreceptors are fully recharged is when you’re the most sensitive to light.
There is some truth to the old wives’ tale that eating carrots will help improve your night vision. There are other easy things you can do to see better in the dark. Try these simple tips to improve your night vision.
- Give your eyes time to adjust when going from a well-lit area to a dark or dimly lit area,
- Protect your eyes during the day by wearing sunglasses, and
- Use red-tinted glasses during the day to prepare your eyes for the dark of night.
You can use these tips to enjoy your favorite Christmas lights this holiday season too!
If you’ve tried these tips and you still aren’t happy with your night vision, you could try improving your overall vision with LASIK. While there’s still time to book a consultation before the holidays, LASIK provides many benefits that will last the whole year through. To learn more about OCLI LASIK surgery and how it can help your vision, including night vision, contact us today.