Sunglasses and Macular Degeneration
by Dan Roberts
Why wear sunglasses?|
If you have a retinal disease, you are probably photosensitive, where too much direct light is painful for your eyes. You also have retinal cells that can be easily damaged by too much light, and some colors of light (even invisible light) have been shown to be hazardous. Additionally, reflected light and glare from horizontal surfaces serve only to compound your problems when you are already dealing with compromised vision.
The right sunglasses can eliminate all or most of these difficulties, allowing you to safely maximize your vision in bright environments. The endless array of choices, however, can be confounding. Hopefully, this article will help you to narrow your options and make your decisions easier.
What your sunglasses should do
1. Totally eliminate "ultraviolet" (UV) rays.
UV rays are of such high frequency that they cannot be seen by the human eye. They are short wavelengths measuring less than 400 nanometers (nm), as illustrated below.
UV rays are divided into two categories, UV-A and UV-B, with UV-A being the most intense. Your cornea absorbs all UV-B, and most UV-A. Over time, however, the UV-A that gets through can damage your lens and retina, so you want to be sure your sunglasses are labeled 100% UV-A and UV-B protective.
2. Reduce or eliminate blue light.
Blue light waves (400-500 nm) are responsible for the haze you see in bright sunlight, and a growing compendium of research is showing that this frequency can also be hazardous to the lens and retina. For a great deal of information on the effect of light on the retina, see "Artificial Lighting and the Blue Light Hazard (The Facts About Lighting and Vision)" in the MD Support Library.
To protect your eyes from blue light and to increase contrast, you need to look for specific tints:
It is important that you realize how 100% blue-blockers will distort other colors. For this reason, you should not drive with them on. You will also find that your color perception will be out of kilter after removing them (yellow school busses will be a beautiful pink, for example). Don't worry, you will return to normal in a few minutes.
3. Reduce light intensity.
Changes in intensity are accomplished by differing levels of "darkness," or "transmission" of the lens. The amount of transmission depends upon your desired comfort and safety level. Be careful that you don't buy dark lenses that are not UV protective. Your eyes will naturally dilate in response to the low intensity, which will increase the amount of UV that enters.
4. Eliminate horizontal glare
Horizontal glare is reflection off of a surface such as water or a roadway. Poloraized lenses will take care of the problem.
5. Protect your eyes from all directions.
Your sunglasses should protect your eyes from the sides, above and below. This is done with shields on the top and sides, and facial contact at the bottom. If you wear prescription glasses, you can purchase fitovers. Or you can have your optometrist make prescription sunglasses that are smaller and contoured to your face. "Clip-on" lenses will not offer enough protection.
6. Extra features
The most important eye-safety concerns have been discussed, but you can also find features such as:
To help organize all of this information, here is a summary for you to take to the store. Buy them if . . .
Here are some dealers in sunglasses that follow honest advertising practices and meet the standards of safety for people with macular degeneration.
Jonathan Paul Eyewear
NoIR Medical Technologies
For more details about the information in this article, see "How Sunglasses Work," by Jeff Tyson