Optimal lighting for those with vision loss varies. Most with low vision benefit from increased illumination, while some visually impaired are light-sensitive and function better at lower light levels.
Sunlight is a natural light source that has the full spectrum of wavelengths. Most with low vision find that natural lighting is the best for their visual functioning, while some with low vision are light-sensitive and find sunlight too harsh.
How to Optimize Lighting for the Visually Impaired
The goal of managing lighting for low vision is to optimize visual function. The correct amount of light is a balance between:
- ambient room lighting,
- direction and brightness of additional light sources,
- the task to be performed, and
- the degree (or type) of vision loss, along with personal preferences.
Ways to Optimize the Lighting in the Home
- change to higher luminance light bulbs for room lighting,
- bring task lighting sources close to the work area,
- reduce glare, and
- increase contrast.
How to Optimize Ambient Room Lighting
Increase the brightness of the light bulbs used in overhead ceiling light fixtures, especially important for hallways, closets, and kitchens.
Additionally, for overhead lighting, modify light switches with dimmers to better control room lighting. This allows those with light-sensitivity to control room lighting.
It can be difficult to navigate a room looking for light switches in the evening and night. Consider connecting light sources to voice-activated personal assistants like Apple’s Siri, Amazon’s Alexa, or Google Assistant. It does require WiFi and smart plugs or smart bulbs. Smart bulbs have the ability to change brightness and color temperature. The Smart bulb systems can be costlier and more difficult to coordinate.
Adjustable window shades, especially for rooms on the sunny side of the home, will help control room lighting.
How to Optimize Light in Work Areas
Tasks such as reading, hobbies, or other work involving detail, utilize directional lighting. Over-the-shoulder lights should be on the opposite side of the person’s preferred hand. This presumably is the hand holding the pen or a magnifier, so the body is not casting a shadow on the reading material.
Directional lamps should have a shade and the light is aimed in the direction of the reading material or work surface. The shade prevents the light from shining into the eyes.
The closer the light source, the better the lighting. Increase the brightness by bringing the light source closer.
Reduce Glare to Optimize Visual Function
Glare will reduce the ability to ‘see’ and cause discomfort and eye fatigue. There are two types of glare: discomfort glare and disabling glare.
Discomfort glare. Glare results when light is reflected and scattered off a surface. The reflected light interferes with the light illuminating the task or object of interest making it more difficult to see.
Disabling glare. Glare can be created when the lighting is too bright. Illumination that is too high can cause discomfort and eye fatigue. Those without eye disease experience this disabling glare on bright sunny days with light reflected off sand or snow. Someone with low vision may experience this same effect in a room with very bright lighting.
Adjustable window shades reduce the glare of incoming sunlight, while still being able to enjoy natural light.
Close directional lighting on paper or work surfaces can be adjusted if the lamp is a ‘gooseneck’ type, where the light direction can be adjusted to minimize glare off the work surface.
Avoid white, shiny, glass, or metallic counters, tables, and desks. Opt for darker or matte finish surfaces or use coverings that absorb rather than reflect light. Consider wearing a hat or visor in rooms with overhead lighting that is causing visual fatigue and discomfort.
How to Increase Contrast to Optimize Visual Function
Contrast sensitivity is the ability to distinguish an object from the background. For example, silver coins placed on a shiny metallic counter will have low contrast (grey on grey). The average sighted person will not have a problem seeing the coins. A person with low contrast sensitivity may not notice the coins. Silver coins placed on a matte white counter will have higher contrast. Someone with low contrast sensitivity will be able to detect the contrast of the silver coins on a white surface.
Many environmental changes can be made, such as changing the color of tables and countertops, avoiding ‘busy’ patterns, adding colorful markings, and modifying the lighting.
Increase the contrast of objects by utilizing lights under counters, use illuminated mirrors, directional lighting for appliance controls, and over-the-shoulder lighting for reading areas. Overhead lighting should be bright enough to fill the room so there are no dim or shadowy areas of low contrast.
What Makes Someone More Light-sensitive?
The best lighting for someone with low vision may depend on the type of eye disease. Those with ocular albinism, achromatopsia, or retinitis pigmentosa will be more light-sensitive than someone with cataracts, macular degeneration, or diabetic retinopathy.
The damage to the retina can result in problems adjusting to different light levels. For example, bright headlights from an on-coming car at night or stepping from a well-lit room into a dark hallway. Those with light sensitivity are ‘dazzled’ by the sudden change in light levels. The inability to adjust to these dramatically different light levels is a problem for the visually disabled.
Interestingly, there is no in-office technology to measure someone’s level of light sensitivity. It is pretty much subjective. In other words, if you have light sensitivity problems you need to tell your eye care practitioner. Those who care for the visually impaired should ask about lighting concerns.
The suggestions for patients who are light-sensitive are not to decrease light completely, but to ensure that light is adjustable for how they are feeling or what they need to ‘see.’ The suggestions made above for ambient room light levels and controlling glare, apply especially to those who are light-sensitive.
- Adjustable window shades,
- dimmable overhead lighting, and
- adjustable task lighting.
Those who are light-sensitive may also benefit from tinted lenses. Tinted lenses will not increase visual acuity or visual function, but can make the light sensitive more comfortable and better able to adjust to different light levels.
A company known for offering tinted lenses for low vision is NOIR .
What are the Best Types of Lights
There are numerous types of lights: incandescent, fluorescent, CFL, halogen, and LED. Here in the states, most incandescent and halogen bulbs will be phased out by August 2023, because of their high energy usage.
I am only going to discuss the types most commonly used in the home and office: fluorescent and LED.
LED bulbs are replacing the incandescent light bulbs in the home. They use far less energy and last longer.
What to look for when purchasing lights for the Home
The two most useful numbers on the box are lumens and light appearance. Lumens indicate brightness. The higher the lumen number, the higher the brightness. Lumen values are between 250 L and 5800 L. After living with incandescent for many years, we are more familiar with ‘watts.’ So here is a comparison.
|25 W||40 W||60 W||75 W||100 W||150 W||300 W|
|200 L +||400 L +||700 L +||1100 L +||1600 L||2000 L +||5000 L|
The other factor to consider is Color Temperature or light appearance. Manufacturers have been able to adjust the ‘color temperature.’ This is indicated as ‘K’ (Kelvin.) More likely it will appear on the box as:
Warm (Soft) White (1900 t0 3200 K),
Neutral White (3500K),
Cool White (4000K), or
By comparison, incandescent light is in the Warm whites, 2300 to 2850 K. In the home, we are more comfortable with the warm cast of the incandescent bulb and should choose warm white LEDs. The Cool White is the blue cast which is usually undesirable.
For example: if you like the warmth of the incandescent, but need bright light, you would look for an LED with something like “Warm (or Soft) White, 2700K, Bright 2600L, 150 Watt equivalent.”
Another factor to consider, for those who need true and natural colors like artists, is the CRI (Color Rendering Index.) The index is 0 to 100. 0 indicates no color distinction, all colors will look neutral. A CRI of 100 indicates natural color rendering. Incandescent bulbs have a CRI of 100. For the most part, LEDs are 80 – 85, with a few rare exceptions.
The last consideration is: Will the bulb be used in a fixture with a dimmer for adjusting light levels? Not all bulbs are ‘dimmable.’ So check for this option.
Fluorescent Lights: The biggest complaint regarding fluorescent lighting is the color rendering and flickering.
Fluorescent lights have been the choice for commercial buildings because they provide broad, bright lighting and are inexpensive to use. However, the light emitted seems harsh and depending on the type, distorts colors. That is because the economical fluorescent lighting is Cool White. The CRI index is low, 50 -60.
Beyond commercial fluorescent lighting, there are different types of fluorescent lighting with better color rendering. The differences depend on the composition of the phosphors used in the bulbs.
Both CFLs and tube-type fluorescent bulbs come in different color temperatures. If choosing fluorescent lighting for the home, look for Soft (or warm) White. If you are looking for high CRI (80 – 90) for truer colors, choose the Daylight fluorescent. Its’ spectrum is more closely related to natural light.
Less expensive or older florescent fixtures can have a strobe-like effect which can cause eye fatigue. The flickering is remedied by installing high-frequency electronic ballasts to prevent flickering (versus the older magnetic -type.)
Check to see if the bulb is dimmable. Dimmable fluorescent lights need to be attached to a dimmable ballast in order to be controlled by a dimmer switch for adjusting light levels.
Learn about other workplace modifications for the visually Impaired: How Do Visually Impaired People Work?
In the End…
Very often those with low vision or those who care about them, do not realize the extent to which good lighting can make a difference in what they can see.
Increasing light levels will help visual acuity, contrast sensitivity, and color perception, but only to a certain point. That optimal amount of light varies by individual. Lighting modifications, in most cases, will help optimize visual function.