"Where are my glasses?" "Please turn up the lights!" "That glare is blinding!" Do you ever hear your parents or even yourself saying these things? Sensory loss is common to the aging process, as witnessed by the number of older people wearing hearing aids and eyeglasses. The automatic response when this happens is to seek help from the medical profession, yet there is a huge role for the design community to create a physical environment that will minimize the effect of sensory loss. With the growth of the 65+ age group expected to peak at 23 percent of the total population between 2030 and 2050, all professional groups will be called upon to meet the challenges posed by this "Age Wave."1
Vision and Aging
Everyone to a greater or lesser degree experiences normal age-related changes to the eye. In addition, the prevalence of eye diseases increases with age, compounding the problems of an already impaired visual system. Visual impairment represents one of the most significant health problems of older people because of the associated dangers affecting the rest of the body, i.e. fall-related hip fractures. Falls are the leading cause of accidental death in the senior population. About 20 percent of seniors who suffer a hip fracture die within a year of the fracture.2
Discoveries in the last few years of the retinal ganglion cells, which provide input to our circadian system (keeping our sleep/wake cycle synchronized with the night/day cycle of light) and the action spectra of 446-477 nanometers as the most potent wavelength region,3 provide additional objectives for a successful lighting design project. Since this range is shifted toward the shorter wavelength, or the blue part of the spectrum (similar to the light of a blue sky), there is added incentive to increase the use of daylight within spaces used by people of all ages, and especially for the senior population.
The normal effect of age-related changes to the eye include less light reaching the retina, increased sensitivity to glare, longer adaptation time required for changes in brightness, loss of contrast sensitivity, loss of accommodation, and distortion of colors due to the yellowing of the lens. Of these six age-related changes to the eye, only one, accommodation, can be corrected by wearing glasses or corrective lenses. The other changes can best be addressed in the physical environment by providing the appropriate quantity and quality of light and increased value contrast between objects and their background, or at a change of level, i.e. the edge of a step or counter edge.
The prescription for quality lighting for older adults is best achieved by using layers of light combining ambient, accent, task, and glow (instead of sparkle). Some considerations to account for are:
- Ambient light must be even and consistent within a space and from one space to another, providing light on the vertical surfaces, avoiding scalloped patterns on the walls or pools of light and/or shadows on the floor. Yes, this does mean that we must end our addiction to recessed downlights.
- Glare is enemy #1! Whether the source is daylight or electric light, direct and reflected glare must be controlled and diffused.
- Provide as much balanced daylight as possible within a space. Fenestrations with diffused glazing located above the field of view are preferred, since they avoid the problems created by glare and shadows.
- It is important to use high-frequency electronic ballasts to avoid flicker and hum associated with the soon to be obsolete magnetic ballasts.
- Light sources rated high on the color-rendering index best minimize the effect of the yellowing lens of the eye. Whereas some designers (and adult children of aging parents) may consider the color of an incandescent light source in the 2700K to 3000K range more residential, older people continually request whiter light sources, especially for task lighting.
- Lighting for visual tasks must include all activities of daily living--grooming, bathing, cooking, cleaning, selecting and matching clothing, laundry, reading and paperwork, and most of all, leisure activities such as crafts and hobbies.
The quantity of light needed for both task and ambient light will vary depending upon individual needs. It is generally accepted that people 60 years of age will receive only one-third the amount of light on the retina as compared to that of people 20 to 30 years of age. Given this and the extreme importance of greater independence and safety, we must begin to design for the "optimum" light level, rather than the "minimum." If you are designing a private residence, be certain to determine the lighting needs of all individuals living there. If the project is a long-term care facility, be aware that the average age of people living in assisted living facilities and nursing homes is 85 years of age. Residents in this age group will experience even greater reduction of light reaching the retina. The best guide for recommended light levels for long-term care facilities can be found in the IESNA/ANSI document: RP-28-2001 Lighting and the Visual Environment for Senior Living.
Indirect lighting is a great solution to providing high ambient light levels without glare. Since linear indirect luminaires are associated with commercial or institutional type building projects, the integration of lighting into architectural elements, i.e. ceiling coffers, ceiling and wall coves, and above the line of sight on top of bookcases and upper cabinets, allows for the use of long energy-efficient fluorescent lamps, while preserving the residential quality of the space. This approach requires close teamwork early on in the design process amongst the lighting designer, architect, and the other design team members.