Lighting and the Aging Eye

a guest post by Lisa J. Reed, Lighting Designer

Getting older? Not you, right? But you know someone who is. The U.S. has an aging population, and we need to design for it. Certain spaces, like medical facilities, are more likely to be visited by seniors. Aging eyes must be one consideration in those designs.

But what kind of light do aging eyes need?

Let's start with how the eye works.

Look at this cross section of a person’s eye. Light enters the eye through the cornea (the clear protective bulge covering the outside of your eye.) Then light passes through the pupil (the dark opening in the center of the colored iris of the eye.) The pupil expands and contracts to admit more or less light. Beyond the pupil is the lens. Ciliary muscles control the lens to focus the incoming light on to the retina at the rear of the eye. Behind the lens is the vitreous humor, which is a clear jelly bag designed to keep the eye round. Then at the rear of the eye is the retina, which is a densely packed set of photoreceptors. These photoreceptors convert the light image into chemical signals and electrical signals, which are then carried to the brain.

Lighting Blog 15 - Eye Diagram
What can happen to the eye as it ages?
 
  • Lens
    • Cataracts decrease vision due to clouding of the lens.
    • Presbyopia is a condition in which the lens loses its ability to focus – most people over 40 experience this and correct it with glasses.
  • Pupils
    • Adaptation, or the ability to adjust to bright or dark environments decreases with age due to the pupil elasticity and velocity decreasing with age.
  • Vitreous Humor
    • Myodesopsia is the perception of “floaters” in the vitreous humor. These are caused by any eye damage that made microscopic material become lodged in the vitreous fluid.
  • Retina and Optic Nerve
    • Macular degeneration causes the loss of the central field of vision, while peripheral vision remains.
    • Glaucoma symptoms include loss of peripheral vision.
    • Diabetic retinopathy patients can suffer from blurred vision and dark spots floating in the visual field.
 
How can lighting help these aging eye problems?

More Light

More light is the answer to most age-related vision problems, but instead of raising overall light levels by 500%, use task light to pump light levels where you need them for reading, grooming, hobbies, etc.

Then increase ambient light levels a little. One easy way to do this is to replace existing lamps with more efficient sources. Replace incandescent lamps with a high quality compact fluorescent or LED lamp to increase ambient light levels without increasing power consumption.

Uniform Light

Combat adaptation struggles by providing uniform light within a room and also from room to room. Help eyes adjust to light level differences from room to room by providing smooth lighting transitions between rooms. Entering a lobby during the daytime can be a different experience than entering it at night. Use daylight and lighting controls to create smooth transitions from outdoors into your building lobby.

Glare Free Light

Beware of glare. Floaters and other imperfections in the eye cause light scatter and naked light bulbs exacerbate this problem. It can be tempting to use sources without shielding to increase light levels, but don’t do it.

Not this:   But this:
Lighting Blog 15 - No Shade
 
Lighting Blog 15 - Shade

Quality lighting is crucial for health and well being for people of all ages. For the elderly, quality lighting can help prevent falls, which is one of the biggest hazards for senior health. For more information on this topic, check out the work of The Center of Design for an Aging Society.

 

Lisa J Reed photo - Lighting Blog

Lisa J. Reed has been attracted to lighting (like a moth to a flame) for 20+ years. She is the Founding Principal at Envision Lighting Design, LLC in St. Louis, where she designs, teaches, and writes about architectural lighting.

 

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