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Traditional ophthalmic training focuses on the patient’s clinical examination and testing. Eye care specialists frequently fail, however, to inquire about a patient’s visual function unless cataract surgery is indicated. Although clinicians learn methods by which to control IOP and the indications for laser or surgical treatment, they are often stumped for suggestions when older patients report visual difficulties despite a “normal” examination or stable ocular disease. Moreover, many eye care specialists do not routinely ask about visual function, not because they lack empathy, but because they lack knowledge of how to improve patients’ visual function in their homes. Helping these individuals is simpler and more intuitive than one might think.
DOES VISUAL FUNCTION IN THE CLINIC REFLECT VISUAL FUNCTION IN THE HOME?
One reason for the discrepancy between a patient’s reported visual difficulties and his or her clinical examination may be that the latter does not accurately reflect visual function in the home. We recently completed a study funded by the National Institutes of Health of 52 normals and 138 glaucoma patients aged 55 to 90 years. We compared measurements of vision (near and distance visual acuity, contrast sensitivity, and glare) and lighting in the clinic and home.1 For all measures of vision, normal individuals and patients with glaucoma performed better overall in the clinic than at home (Table 1). Approximately one-half of all participants had better near and distance visual acuity in the clinic than in the home. Specifically, 29% of glaucoma patients read 2 or more lines better on distance visual acuity testing in the clinic than at home. Forty-three percent of patients with advanced glaucoma read 3 or more lines better in the clinic than at home. Although contrast sensitivity testing was also better in the clinic, we found the greatest difference with glare testing: almost three-quarters of all patients performed better in the clinic than at home.
The results of our investigation reflect those of an earlier study of low-vision patients.2 These studies highlight that clinical measurements may not accurately reflect a patient’s visual function in his or her home, even if he or she has no ocular disease. More important, this research suggests that a large proportion of patients are not functioning at their maximum visual potential in their homes.
THE ROLE OF LIGHTING
In our study, we found lighting to be the most significant factor associated with differences in visual function measured in the clinic and home. Lighting levels were almost three to four times lower in the home compared to the clinic. In addition, 87% and 91% of patients had home lighting below the recommended levels in areas used for distance and near vision, respectively.
Improved lighting has been associated with better visual acuity in 63% of community-dwelling older adults3 and 82% of older adults with low vision.2 Greater illumination at home has also been associated with improved reading ability for patients with macular degeneration,4 improved activities of daily living and quality of life,5 and a possible reduction in the number of falls.6
The take-home message here is simple. Eye care specialists should routinely ask patients about their visual function at home. If they report difficulties, a simple and likely effective recommendation is to improve lighting.
The following list of general guidelines7 may be useful for patients who are experiencing visual difficulties in their homes. It is important to note, however, that the vision of certain individuals may worsen due to glare and light/dark adaptation. These patients may prefer bulbs different from those we recommend. A client-centered, individualized, in-home evaluation by an occupational therapist may be most beneficial to patients.
No. 1. Raise Home Lighting Levels
Table 2 lists the Illuminating Engineering Society of North America’s recommended lighting levels.8 In general, task lighting (eg, 1,000 lux) should be three times greater than general lighting (eg, 300 lux) to help people discriminate fine details and low-contrast objects.
People should use adjustable task lighting for near tasks. They can place task lights with goosenecks or articulated features below eye level and position the lights to avoid glare from the bulb (eg, reflections from the TV or computer screen). Placing adjustable task lighting over one’s shoulder for reading and opposite one’s dominant hand for writing will reduce interference from shadows. Repositioning the light source closer to the reading material can significantly increase lighting levels.
Using high-quality T8 fluorescent bulbs or tubes operating on an electronic ballast helps to decrease flickering light, noise, and headaches. Modern fluorescent bulbs are superior to incandescent bulbs, because the former produce less glare, are more energy efficient, and are easier to change due to their cooler temperature. When replacing an incandescent bulb with a fluorescent bulb, people should use one-third the wattage of the incandescent bulb to obtain the same illumination.
Diffuse, light-colored walls, ceilings, and floors may increase the light reflected in the room.
No. 2. Balance Lighting Levels
Patients should strive to keep the lighting levels similar throughout the house to reduce difficulties from light/dark adaptation—particularly important in transitional areas such as hallways and foyers. Nightlights are useful in transitional areas such as the pathway to the bathroom or in the bedroom between the door and the bed.
No. 3. Minimize Glare
Opaque or translucent shades can reduce glare. Patients with visual difficulties at home should avoid clear-glass light fixtures. They can adjust the position of lighting to avoid direct glare to their eyes or indirect glare on an object. The use of blinds and curtains can decrease glare from windows.
No. 4. Heighten Contrast
Paint or colored tape can increase the delineation of the edges of stairs, ramps, or doorways. For example, white markings at the edge of a darkly colored step may help the patient ascend and descend stairs. People can also use colors to facilitate their everyday activities. For example, they can use white cups when pouring coffee and darkly colored cups when pouring milk.
No. 5. Increase Color Perception
Greater lighting at home will make it easier for patients to recognize colors. They should use high-quality fluorescent bulbs with a correlated color temperature of 2,700 or 3,500 K and a minimum color rendering index of 80 (bulbs designated as 827, 830, or 835).
No. 6. Make a Referral
It can be worthwhile to refer patients to an occupational therapist or low vision specialist, who can provide customized recommendations. Occupational therapists can evaluate the patient’s lighting and make task-specific suggestions tailored to the home environment. Examples of specific strategies include
- enabling patients to increase their independence in self-care, work, leisure, and mobility in the community
- instructing patients on the use of optical devices for daily activities
- helping patients to effectively use their functional vision through eccentric viewing and scanning strategies
- teaching patients how to modify their environment to maximize their vision and safety
Patients’ visual function at home may be worse than their eye care specialists would suspect based on clinical testing. Individuals who report visual difficulties despite a stable or normal examination may benefit from improved lighting and decreased glare at home or other simple modifications. By regularly asking questions, offering simple recommendations, and making referrals as needed, clinicians can identify problems and promote safe, independent living for their patients.
The study described in this article was supported by NEI grant 1K23EY017616-01, Pfizer Inc., the American Glaucoma Society, the Harvey A. Friedman Center for Aging and Dr. Morris grant 5K07AG2116405, an unrestricted grant from Research to Prevent Blindness, and the NIH Vision Core Grant P30 EY02687.
Anjali M. Bhorade, MD, MSCI, is an assistant professor of ophthalmology at Washington University School of Medicine in St. Louis. Dr. Bhorade may be reached at firstname.lastname@example.org.
Monica Perlmutter, MA, OTR/L, SCLV, is an occupational therapist specializing in low vision rehabilitation at the Program in Occupational Therapy at Washington University School of Medicine in St. Louis. Ms. Perlmutter may be reached at email@example.com.