Can Insufficient Lighting Account for Vision Disparities between the Doctor's Office and Home?

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a task lamp with flexible arm

A team of American researchers has presented evidence that vision measured in the clinic is generally better than vision measured at home and conclude that vision discrepancies between patient reports and clinical testing may be due, in part, to poor or inappropriate home lighting.

The research, entitled Differences in Vision between Clinic and Home and the Effect of Lighting in Older Adults with and Without Glaucoma, was published in the November 21, 2013 issue of JAMA Ophthalmology (formerly Archives of Ophthalmology). JAMA Ophthalmology is an international peer-reviewed journal published monthly by the American Medical Association.

The authors are Anjali M. Bhorade, MD, MSCI; Monica S. Perlmutter, OTD, OTR/L; Brad Wilson, MA; Jamie Kambarian; Sidney Chang, MD; Melike Pekmezci, MD; and Mae Gordon, PhD, who represent the following institutions: Washington University School of Medicine, St. Louis, Missouri; and the University of California, San Francisco.

About the Research

From Older adults don't see as well at home as in the clinic via Reuters.com:

When older people have their vision tested in a doctor's office, the results might not reflect how well they actually see at home, according to a new study. Researchers suggest the difference could be due to poor lighting in people's homes.

"A simple awareness of this discrepancy between vision in the clinic and home may alert the clinician to recommend increased lighting or refer these patients for an in-home evaluation by an occupational therapist or low vision rehabilitation specialist," [study leader] Dr. Anjali M. Bhorade said.

Between 2005 and 2009, she and her colleagues studied 175 people age 55 and older, 126 of whom had glaucoma, an eye condition that leads to damage of the optic nerve. Participants went to a clinic for eye exams and were visited at home, where the researchers tested their vision and recorded light levels. More than half scored better on eye tests in the doctor's office compared to at home. The difference seemed to be greater for people with more severe glaucoma.

Though the new findings come primarily from a group of patients with glaucoma, they have implications for older adults with and without the condition. [One] concern could be that patients with cataracts who complain that too much glare makes it difficult to see may not qualify for cataract surgery if their vision is tested in the office, but would qualify if tested at home, [Dr. Bhorade] added.

More about the Study from JAMA Ophthalmology

From the article abstract:

Objective: To compare vision measured between the clinic and home and evaluate factors, including lighting, associated with these differences.

Design, Setting, and Participants: This cross-sectional study conducted from 2005-2009 involved 126 patients with glaucoma and 49 without glaucoma recruited from the Glaucoma and Comprehensive Eye Clinics at Washington University, St. Louis, Missouri. Patients underwent clinic and home visits, were aged 55 to 90 years … and met inclusion criteria for this study.

Exposure: Participants underwent clinic and home visits, randomized to order of completion. At each visit … examiners measured binocular distance visual acuity with a non-backlit chart, near visual acuity, contrast sensitivity, contrast sensitivity with glare, and lighting.

Results: The mean scores for all vision tests were significantly better in the clinic than home for participants with and without glaucoma … Lighting was the most significant factor associated with differences in vision between the clinic and home… Median home lighting was 4.3 times and 2.8 times lower than clinic lighting in areas tested for distance visual acuity and near visual acuity, respectively. Home lighting was below [recommended levels] in 85% or greater of participants.

Lighting and Low Vision

Lighting is always an important consideration for persons who have low vision. Also, it's important to realize that our lighting needs gradually (and naturally) change over time as we grow older. As an example, the equivalent of a 100-watt bulb required for reading or other close work at age 20 increases to:

  • 120 watts at age 30
  • 145 watts at age 40
  • 180 watts at age 50
  • 230 watts at age 60
  • 300 watts at age 70
  • 400 watts at age 80

Many of us, however, don't increase the wattage of our lighting fixtures at home to accommodate this need for additional light.

Increased Home Lighting and Safety

Although increased lighting at home is usually helpful, it is not recommended that you create additional illumination simply by placing a higher-wattage bulb into an existing light fixture or lamp:

  • Most manufacturers of lighting fixtures provide information about maximum recommended wattage limits, since exceeding the recommended wattage could cause fire or injury.
  • In addition, putting a high-wattage bulb into a ceiling fixture will not necessarily produce better, more functional light; instead, it could increase glare and create more and deeper shadows.
a task lamp with flexible arm

To create better lighting in a work area for reading, cooking, using the telephone, or doing crafts, a "task lamp" (pictured at left) can be helpful. It can be either a floor or table lamp with a flexible arm or gooseneck that allows you to adjust the height and direction of the light and focus it directly on your work area.

Here's another helpful lighting tip: Cutting the distance in half between a light source and the task (by bringing the light closer to your work) will make the brightness or intensity of the light approximately four times greater.

Thus, you don't necessarily have to purchase a stronger light bulb; instead, it is helpful to move the light closer to your work. A flexible-arm task lamp is ideal for this purpose. It is usually more effective to use a task lamp with a regular 40- or 60-watt bulb closer to your work area than to use a 250-watt bulb in a ceiling fixture.

More Information about Lighting

The video series Better Lighting for Better Sight, featuring Bryan Gerritsen, M.A., CLVT, contains information about critical factors that can enhance vision, including different types of lighting, positioning of lights, contrast sensitivity, and control of glare. The series is available for purchase through AFB Press.

You can also find information on Lighting and Glare at VisionAware.org.


Topics:
Low Vision
Home modification
Environmental assessment and modification

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