• Full Spectrum. The closest to actual sunlight, covering the entire range of colors and peaking in the blue light spectrum. Blue light is responsible for glare, and some studies have shown that intense exposure to it may be harmful Incandescent: Although close to natural sunlight, this type of light tends to be concentrated on a few areas, leaving others in a bit of shadow or glare. It is also no longer mass produced since the mid-2000's when more energy efficient bulbs hit the market.
• Incandescent. Close to natural sunlight, can concentrate on area but leave other areas in shadow or glare. A yellowish correlated color temperature (CCT) of about 2800K (Kelvin) was safe for the retina. It was not, however, suitable for contrast, accurate color perception, or economy.
• Tungsten-halogen (or simply "halogen"). A bright "warm white" light (about 3200K) is suitable for enhancing contrast. Halogen lamps are good for use where an intense light with excellent illumination is needed in a room. Halogen is best for viewing contrast between objects, images, and surroundings. Halogen lamps have higher heat intensity and can be hazardous and uncomfortable when used in task lamps.
• Fluorescent. Bright, safe, and economical, this type of lighting is seen most often in public places. Modern fluorescent tube lamps and "compact fluorescents" are usually in the upper "warm white" range (about 4500K), so they are bright and safe for the eyes.
• LED (light-emitting diode). Generally, the more expansive, brighter, and closer the light field, the more potential risk it carries for the retina. LED light is appropriate when you need a safe light concentrated on a particular spot for a specific function. The U.S. Department of Energy states in its 2013 "Optical Safety of LEDs" fact sheet that the proportion of blue emissions by LEDs "is not significantly higher…than it is for any other light source at the same CCT."
It's essential to understand the difference between lux, lumens, wattage, and CRI (Color Rendering Index). That's because they can significantly impact the quality of life for people with vision difficulties;
Lux is a way of measuring how intense a light is, also known as 'illumination.' For example, a typical living room probably has 50 lux. In comparison, a grocery store or shopping mall may have closer to 750 lux.
Lumen means how much light is emitted from a particular lighting source. The higher the lumen, the brighter the light.
Wattage is the amount of energy that a product consumes, similar to a mobile phone battery's usage.
Color Rendering Index, or CRI, is how a lighting source displays color compared to natural light. So you may see something in the sunlight that looks dark green, while in artificial light, it may appear a much brighter shade of green.
Both Lux and CRI are the most critical factors for your lighting needs because they affect how you see the world.
Roy Cole, O.D. (retired director of Vision Program Development, Lighthouse Guild) offers the following suggestions for choosing the best lighting.
For task lighting, the lamp (bulb) should be in an adjustable fixture, and the distance of the light source from the page is as important as wattage. The further away the lamp, the less illumination on the page, and the closer, the more illumination. In fact, if you double the distance, you need a light source 4X as strong to keep the same brightness on the page. Triple the distance, and you will need 9X as strong a bulb, etc. This is referred to as the "inverse distance squared rule." So adjust the distance of the lamp for optimal visibility.
To reduce the heat of the bulb, use a lamp with an internal reflector (a double shade). This reduces the heat significantly and allows you to have the lamp closer to the face than you would with a single shade (especially one made of metal).
Here are some other guidelines from Dr. Cole:
If one eye is better and used for reading, position the lamp on that side of the body, slightly to the side. What you don't want is the light reflecting from the page into your eyes. To check this, turn the light off, place a mirror on the page being read, and see if the lamp appears in the mirror. If it does, re-position it. It should still be close to the page, and to the side of your face, but now perhaps at a slightly greater angle. (Of course, too much of an angle will also reduce the brightness on the page, so you have to find the optimal position for you.) You also want to adjust the light so there are no shadows on the page.
A typoscope is a black card with a slot cut in it to expose the line being read as you move it down the page. This will help to reduce the glare reflecting off the page and improve the apparent contrast of the print.
Glare from reflective surfaces can be a hindrance for people whose eyes are not capable of modulating light, due to retinal disease. Blue blocking glasses can help by cutting down the haze which surrounds bright objects (caused by blue light waves, which are very short and easily scattered.) Polarized sunglasses will help to reduce glare, especially if the light is reflecting off of a flat surface that is in front of the viewer (eg. a body of water, snow, or a wet road.) The reason for this is that light reflected at a particular angle is "plane polarized" (in the horizontal direction). Polarized lenses transmit light only in the vertical direction, thus removing the reflected horizontal light.
Blue blocking lenses and polarized sunglasses may be purchased commercially, or optometrists can add blue-blocking tint or polarization filters to prescription lenses. Adding tint to prescription glasses can, however, create a safety issue, since the tint will diminish vision in low light. A better option is to wear tinted blue blocking "fit-over" sunglasses that can be removed when not needed.
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Suggestions for Better Lighting
• Use indirect pathway lighting such as this under bed motion sensor lighting. (see photo below)
• Place the light directly where you need it. Swivel lamps are preferable, as they can be raised or lowered in order to direct the light.
• Aim the light directly on the task at hand.
• Install dimmer switches for controlling the amount of light in the room.
• Install under-cabinet lighting for tasks in the kitchen or work areas.
• Install extra lighting in places where it may be difficult to move around, such as hallways and stairs.
• Install light switches in accessible locations.
• Install switch plates that are lighted or contrast with wall color.
• Install preset light timers in difficult areas.
• Watch television in a lighted room. It is easier on the eyes. Be sure, however, that the light isn't placed where it will cause glare or reflection off of the screen. This can be easily checked with the television screen dark.
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Recommended Low Vision Reading/Task Lamps
Based upon the above information, here is a list of criteria for choosing the brightest and safest lighting for reading or doing close work.
First, an LED light source is recommended for comfort, safety, and economy. In order of importance, these are the specifications to consider:
· 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
Note that there is a State-specific Division of Blind Services in every State in The United States, and it is an excellent resource if your loved one is having difficulty seeing. They offer services and resources to all ages, from infants to geriatrics. For example, I reside in Florida. The Florida Division of Blind Services has a specific, focused program for adults- Independent Living. (click on this link to go to their page)
"The goal of the Independent Living - Adult Program is to enable blind and severely visually impaired adults to live more independently in their homes and communities with a maximum degree of self-direction.- Adult Program is to enable blind and severely visually impaired adults to live more independently in their homes and communities with a maximum degree of self-direction."