Planning to Buy Sun Glasses?
Just what do we need to know before we buy sun glasses?
Finding the right pair among all the hundreds of choices is not an easy task. Salespeople rarely have a clue about protection from the sun, except to repeat the manufacturers' claims - and most claim their glasses will protect you from 100 percent of UV light. But there are no labels on many glasses, especially the higher-priced ones.
How reliable are the stickers and claims you find on sunglasses? In a review, it was found that thirty-three out of forty inexpensive lenses transmitted more than the stated amount of ultraviolet light, and one pair that said it filtered out "up to 98 percent" of UV radiation in fact let in nearly 10 percent.
What You Need to Know
Remember that to provide the best possible protection for your vision at all times and in all conditions, you will need more than one pair of sunglasses.
For activities that take place in very bright sunlight, with lots of glare, you should have very dark lenses that will not be safe to use when driving. Therefore, your choice of sunglasses depends on the activity for which you will wear them.
For optimum protection, we would need both 100 percent shelter from UV light, to prevent cataracts, and 100 percent shelter from visible light, to prevent macular degeneration. Unfortunately the resulting lenses would be solid black, and we would not be able to see anything. What we need is the best possible balance between protection and comfort.
Because it is not possible to protect yourself completely from visible light if you want to see, your goal is to selectively reduce the amount of the more dangerous visible rays. Sunglass manufacturers rarely provide enough infor~ation to assist you in this decision. To help you in selectIng sunglasses, I have spent countless hours analyzing numerous sunglasses to determine which lenses provide the best protection.
A Checklist When You Buy Sun Glasses
Here is a checklist with a review of what you need to know when you buy sun glasses, so that you are protecting your eyes not only from UV light, but also from visible light, and the risk of macular degeneration.
- UV protection Always get 100 percent UV protection. A tag that says "meets ANSI standards" is not good enough.
- Visible light transmission Buy the darkest sunglasses that will allow you to comfortably perform the activity you are planning. For regular wear, buy sun glasses that transmit no more than 12 percent of visible light (ANSI special purpose or general purpose, CE level 3 or 4) and between 2 and 5 percent of blue light. For driving, buy sun glasses that transmit between 7 and 12 percent of visible light (ANSI general purpose, CE level 3) so you can see the traffic signals.
- Color Brown or tan lenses offer the best balance between comfort and protection; gray or green is the next best choice. Gray lenses are good for photography and painting, as they introduce the least color distortion.
- Polarization This is preferred for everything except skiing, driving in icy climates, or flying in a plane with polarized windows.
- Lens material Polycarbonate is best overall, and for sports. Glass transmits a clearer image and scratches less easily, but is heavier and can injure the eye if it breaks. Glass is better suited for driving, traveling, sightseeing, and shopping. It is also better if you are a photographer or an artist.
- Photochromic (transitional) These are not ideal for protection, and work best in cold climates. Glass photo chromic lenses are best for driving. Plastic lenses do not darken except when exposed to direct sunlight, and so are not good for driving.
- Coatings All plastic (CR39, acrylic) and polycarbonate lenses should have scratch-resistant coatings. Mirror coating is good when sunglasses are for sports with a lot of glare, such as skiing or fishing. Antireflective coatings are good for driving or walking, but not for sports.
- Frames Bigger is better, but only if they fit closely to your eyes. Wraparound frames offer excellent protection.
- Clip-ons These will scratch plastic corrective lenses, and are best used in combination with glass lenses.
- Optical quality and distortion Check for distortion with an Amsler grid or by looking at a vertical pole to make sure there is no curve in the line.
- Price This has little to do with sun protection. When you buy sun glasses, pay more only for better optical quality and more durable frames.