by Dan Roberts
Advancements in lighting technology for the visually impaired have made big strides during the past 12 years. Before 2005, companies were touting their new full spectrum (“daylight”) lamps as “healthy for aging eyes”. Patients, and even their doctors, were led to believe that the sun at high noon is the best and brightest light source.
Thanks, however, to a good deal of pushback from researchers and knowledgable consumers, lighting companies have either vacated the low vision market or made welcome adjustments. Realizing that lamps imitating sunlight neither improve the health nor benefit the retina, and realizing that the low vision community is now aware of the potential harm to the eyes of extended exposure to near-UV blue light(1) safer lamps are now showing up in the stores.
Sadly, full spectrum lamps have not yet disappeared, and their numbers have actually increased to more than 25 different models. These lamps contain such high blue content (over 5000K) that they fool the brain into thinking they are actually brighter than those with cooler color temperatures. When compared side-by-side, however, the differences can be easily seen.(2)
The good news is that about half of full spectrum lamps are now featuring adjustable color temperature settings. This means that users can choose the kind of light they find most comfortable, from “very warm” (~2800K) to “very cool” (~6500K), with the safest and best “warm white” somewhere in the middle (3400K to 4800K). This is an acceptable compromise, as long as users apply good judgment.
Another change in the industry has been the switch to LED technology, which enables whiter, brighter, and more economical lighting. These tiny light sources are extremely bright, but the U.S. Department of Energy assures that the proportion of blue emissions by LEDs “is not significantly higher…than it is for any other light source at the same [color temperature].”(3)
The industry is moving in the right direction, but there is still room for improvement in the following areas:
- Correlated color temperature (CCT) range of 3000K-4,800K (“warm-to-neutral white”) for eye safety and best contrast
- Color rendering index (CRI) of at least 80 for good color perception.
- Brightness range of 1000-2000 LUX at 12 inches (30 cm)
- Dimmable to alleviate eye strain
- Easily adjustable fixture to prevent glare
- Easy location and operation of fixture controls
- Coverage diameter of at least 12 inches (30 cm) at a distance of 12 inches (30 cm)
- Cost comparable to similar products
- Sturdy construction for safety and durability
- Transparent and educational advertising
In a recent market survey by MD Support, only four companies satisfactorily met all 10 of these standards for safety and quality. They deserve mention here:
Berryessa Designs
Dr. Lite
Trond
Sunvalley Brands
For more information about their products, plus an easy-to-understand discussion of the topics covered in this article, visit “Lighting For Low Vision” on this site.
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REFERENCES
(1) Artificial Lighting and the Blue Light Hazard by Dan Roberts. (MD Support, 2004. Updated 2018.)
(2) Live Comparison of Representative Lamps by Dan Roberts. (From “Artificial Lighting and the Blue Light Hazard”. MD Support, 2018.)
(3) Optical Safety of LEDs (U.S. Department of Energy, 2013.)