According to the American Optometric Association (AOA), studies have shown that daytime exposure to ordinary sunlight can produce temporary but cumulative aftereffects on dark adaptation and night vision. Your patients may know the importance of wearing sunglasses during the day, but they should know that high-quality polarized sunglasses can also help reduce night vision degradation.
Here's what you should know about sunglasses that can help protect your patients against loss of night vision.
What is night vision?
Night vision is the ability to see in low-light conditions. The American Academy of Ophthalmology says that these are the main differences between daytime vision and night vision:
- The pupils become larger and the eye allows in more light when it’s dark outside.
- A different, more sensitive kind of cell in the eye — rod cells — collects the light for night vision.
- Night vision is mostly or completely in black and white. Color vision is poor in very low light conditions.
As you know, during the day we use high-resolution photoreceptor cells called cones, and at night, our eyes must switch to the lower resolution rods. Both are essential for vision, yet sunlight can get in the way of them both working together.
During bright days, our eyes actually “turn off” our rods. The longer they are turned off, and the brighter the sun, the longer they can take to turn back on once the sun sets. To help your patients understand the scientific aspect of dark adaptation, compare it to waking up in the middle of the night to get a drink of water. As soon as you turn the light back off, you can’t see anything, but if you give it a few minutes, you’ll be able to make it back to bed without stubbing your toe.
Extended daytime exposure to bright sunlight can compound this effect, making the importance of light-blocking sunglasses apparent.
Why dark adaptation is so important
According to the Insurance Institute for Highway Safety, the most dangerous time to drive is between 3 and 7 PM. Not only are there more vehicles on the road, but drivers have to contend with changing light conditions.
Glare from the setting sun and low-light conditions after sunset both impact visibility while driving and cause dangerous night vision problems.
It’s possible that more accidents can be avoided by wearing sunglasses that adequately block UV exposure from the eyes. This will improve your patients' driving at night because it will help the eyes adapt more quickly after sunset and avoid glare from bright lights along their route.
Protecting night vision as you age
It’s important to think of high-quality sunglasses as an essential part of eye care for each of your patients. By blocking UV and HEV light they protect the eyes from damage, but patients don’t understand the less apparent benefits, such as low-light adaptation.
As your patients age, their ability to adapt to changing light conditions diminishes. This makes light-blocking sunglasses even more important for your patients over 50. The AOA recommends a few tips for protecting operational night vision — tips you can share with your patients of any age as a way to keep the conversation going around sunwear. Here are a few:
- Look away: never look directly at an oncoming vehicle
- Keep it clean: clean your windshield, outside and inside & clean your headlight coverings
- Adjust your lights: ensure that headlights are properly positioned
- Keep it clear: prescription eyeglass lenses should have anti-reflection coating in order to minimize reflections from dashboard lights, street lights, and lights from other vehicles.
- Adopt an eye-healthy diet: improve your night vision by eating lutein and zeaxanthin-rich foods such as kale, collard greens, and spinach, or via appropriate supplementation.
- Remember to blink: increased concentration can reduce blink rate, which can cause or exacerbate dry eye symptoms, especially when wearing contact lenses.
- Visit your eye doctor: some patients require different eyeglasses for driving at night compared to daylight.
The benefits of polarized sunglasses for improving night vision
The best sunglasses to wear during the day to protect night vision should provide 100% UV protection, HEV protection, and block 85% of visible light.
The answer your patients need: polarized sunglasses. Read our white paper, Why Go Polarized to help you explain to your patients that only polarized sunglass lenses have the technology required to selectively reduce the brightness of reflected light rays to a greater degree than the brightness of surrounding objects.
By doing so, bright reflections are minimized for a more uniformly illuminated visual field—which means greater comfort and better visibility.