There is a lot of confusion regarding which sunglasses are actually best for your eyes. A lot of confusion. I hope this can “clear” things up for you.
The first thing to understand is that sunlight is composed of many different types of light. Sunlight is white in color, but is a mixture of all of the colors of the rainbow, from red to green to blue. A prism separates the white light into these different color parts. None of these parts, including the blue light, is harmful to your eyes. But sunlight also contains ultraviolet light, also known as UV, which is very harmful to your eyes. After many years of exposure, ultraviolet light can cause cataracts and macular degeneration, which is the leading cause of blindness in the United States.
Therefore, you want to keep the ultraviolet light out of your eyes. This is what sunglasses do; sunglasses cut out the ultraviolet light. Please note that ultraviolet light is completely invisible — our eyes cannot see ultraviolet light at all, just like we cannot see x-ray light. So sunglasses can be completely clear and still cut out the harmful ultraviolet light. The tint of sunglasses will cut down the visible light, which is not harmful to the eyes, though the visible light can make your eyes feel sensitive if it is bright. In terms of the health of your eyes, the tint is not important. All sunglasses sold legally in the United States cut out the vast majority of the UV light and are therefore suitable for use when in the sun.
What about polarized sunglasses? Polarized sunglasses decrease the glare that occurs when light reflects off of surfaces such as roads and water. This does not affect how much UV light enters your eyes, so it is not important for your health. Get polarized sunglasses if you like the lesser amount of glare.
What color sunglass lenses are best? Regarding the health of your eyes, it does not matter. Neutral gray keeps the most accurate color balance. Yellow has better contrast in low light. It is a matter of personal taste.
Note: sunglasses are only important when actually in the sunlight. Glass windows, such as in your car, block out most of the UV light, so you do not need sunglasses to protect your eyes if the sunlight is passing through glass.
Indoor, artifical light does not have any significant UV light, so you do not need sunglasses when indoors to protect your eyes.