Abstract
Occupational therapy practitioners who provide low vision rehabilitation routinely complete visual screening assessments to understand how the client’s vision has affected occupational performance (Schuchard & Barstow, 2008). However, occupational therapy practitioners who work in general rehabilitation are less likely to complete vision screenings even though they commonly encounter vision impairment in older clients referred to therapy to address another functional limitation (Park, Mayer, Moghimi, Park, & Deremeik, 2005; Wainapel, 2001; Winner, Yuen, Vogtle, & Warren, 2014).
Occupational therapy vision assessments typically include screening of visual acuity and contrast sensitivity (Warren, 2012). Visual acuity is the ability to see high-contrast details, such as letters and numbers, as they become smaller, and it supports reading performance. Contrast sensitivity is the ability to detect objects as they degrade in contrast from their surroundings, and it supports the ability to detect borders and shapes for safe navigation, facial recognition, and everyday tasks with low-contrast features such as identifying coins. Visual acuity and contrast sensitivity are commonly reduced in older adults as a result of normal age-related visual changes; age-related eye diseases including age-related macular degeneration, cataract, and glaucoma; and systemic diseases that include visual side effects such as diabetes, stroke, and Parkinson’s disease (Biousse et al., 2004; Brabyn, Haegerstrom-Portnoy, Schneck, & Lott, 2000; Congdon et al., 2004; Park et al., 2005; Suchoff et al., 2008; Zhang et al., 2008).
Older adults with eye diseases and visual conditions often experience significant declines in acuity and contrast sensitivity with corresponding significant limitations in activities of daily living (ADLs), resulting in the need for low vision rehabilitation (Jackson & Owsley, 2003). In contrast, older adults without eye disease typically experience only small, slowly developing declines in visual acuity and usually retain vision within the normal acuity ranges (Brabyn, Schneck, Haegerstrom-Portnoy, & Lott, 2001; Lam et al., 2013). However, even these small acuity declines may limit the normally sighted older adult’s ability to complete ADLs. Lam et al. (2013) found that older adults with baseline 20/20 vision, whose visual acuity declined over an 8-yr period but remained within normal limits, reported increasing difficulty completing two to three instrumental activities of daily living (IADLs). The relationship between declining visual acuity and increased ADL limitations was significant and occurred independently of other covariates in the Lam et al. study.
Other longitudinal studies have shown that older adults without eye disease gradually lose contrast sensitivity function (CSF) as they progress into old age. Brabyn et al. (2000) reported that an average 90-yr-old required 6 times more contrast to see as well as a younger person under everyday viewing conditions.
The presence of vision impairment in an older adult client receiving rehabilitation may affect the outcome of the occupational therapy intervention. Cimarolli, Morse, Horowitz, and Reinhardt (2012) reported that vision impairment negatively affected the use of occupational therapy services and predicted higher functional dependence at discharge in older adults in a subacute rehabilitation setting. Similarly, vision impairment was shown to reduce the effectiveness of rehabilitation after a hip fracture (Lieberman, Friger, & Lieberman, 2004). Although visual impairment is associated with an increased risk of falls (Ivers, Cumming, Mitchell, Simpson, & Peduto, 2003; Lord, 2006) and people with vision impairment are overrepresented in cases of hip fracture (Cox et al., 2005b), visual screenings are not routinely conducted with patients hospitalized after hip fracture (Squirrell et al., 2005).
The purpose of this study was to assess the visual acuity and contrast sensitivity of older adults admitted to a trauma orthopedic unit over a 4-mo period using standardized screening assessments used by occupational therapists. The orthopedic unit was chosen because it represented a common rehabilitation setting for occupational therapy intervention. The study sought to determine whether visual screening was necessary for clients referred for therapy on a general rehabilitation unit and the level of vision available to the patients to complete everyday tasks in a typical hospital environment.
Method
Research Design
We used a cross-sectional observational research design. Participants were recruited between February and May 2012 from the South Infirmary-Victoria University Hospital, Cork, Ireland. The Cork Research Ethics Committee and the Institutional Review Board of the University of Alabama at Birmingham approved the study.
Participants
A convenience sample of 50 patients was recruited from among people referred for occupational therapy services after admission to the inpatient trauma orthopedic unit. Inclusion criteria included a minimum age of 65 yr and minimal risk for dementia, as defined by fewer than five errors on the Short Portable Mental Status Questionnaire (Pfeiffer, 1975).
Potential participants were screened and provided consent during the occupational therapy initial interview. Qualified participants were asked whether they habitually wore corrective lenses and whether they had their glasses with them in the hospital. When an absence of glasses was noted, the participant was requested to have his or her glasses brought to the hospital before the examination session.
Instruments
Three standardized screening charts were used to measure distance acuity, reading acuity, and contrast sensitivity. The charts were part of a larger test battery, the Brain Injury Visual Assessment Battery for Adults (Warren, 1998). They were selected for the study because they are screening charts commonly used by occupational therapists. They are standardized in chart design and procedures and conform to recommendations pertaining to the measurement of visual acuity, as outlined by the international societies of ophthalmologists and optometrists (Consilium Ophthamologicum Universale, 1984; World Health Organization, 2003).
The Low Vision Lea Numbers Intermediate Acuity Test Chart was used to screen distance acuity at 1-m test distance; the chart measures acuities from 20/20 to 20/1,000 Snellen acuity. Reading acuity was measured using the Warren Text Card. The chart contains 14 short 5th-grade reading-level sentences administered at 40-cm test distance to measure reading acuity between 20/20 and 20/400 Snellen acuity. CSF was measured using the Lea Numbers Low Contrast Screener at a distance of 40 cm. The chart consists of Sloan numbers presented at five diminishing contrast levels ranging from 25% to 1.25% to screen for contrast ability at the levels needed for safe mobility in the environment. The test provides a descriptive functional interpretation of client performance at each level, based on the expert opinion of the chart developer, Lea Hyvarinen (Warren, 1998). The descriptive format was used to interpret participant performance in the study. Psychometric properties have not been established for these screenings.
Procedure
One investigator (Roche) administered the assessments. The data were collected during a single session conducted in a quiet room, except for 3 participants who were assessed in their private rooms because of medical complications. Participants remained seated throughout the 10- to 15-min session and were given rest breaks as needed.
Participants were briefly interviewed to obtain self-report information about recent falls, presence of eye disease or conditions, last eye examination, and glasses prescription. The participants were tested wearing their habitual correction (glasses). The condition of the participants’ glasses was examined, and whether the glasses were dirty, scratched, broken, or ill fitting was noted. The glasses were thoroughly cleaned before conducting the assessments. Six participants did not have their distance glasses with them during testing, and 3 did not have their reading glasses.
Distance acuity was measured first, followed by reading acuity and contrast sensitivity. All of the study participants were tested under the recommended lighting condition for acuity screening in which the chart is fully illuminated. The recommended lighting was achieved using a combination of overhead room lighting (a total of 24 18-W fluorescent tubes) and a DaylightTM floor lamp (Daylight Company Ltd., London) with an 18-W energy-saving tube (1,200 lumens) situated as close as possible to the acuity charts and directed onto them. To study the potential effect of lighting on participant performance, 25 of the participants were retested using only the overhead lighting to assess performance under the typical lighting available to patients participating in treatment sessions on the orthopedic unit.
Data Analysis
IBM SPSS Version 20 (IBM, Armonk, NY) was used to analyze the data. The data analysis included descriptive statistics and cross-tabulation procedures. A nonparametric test, Wilcoxon signed rank, was used to compare group visual acuity outcomes under the two lighting conditions (Portney & Watkins, 2009).
Results
Sample Characteristics
The study sample comprised 9 men and 41 women age 65 to 90 yr (mean age = 79.2 yr, standard deviation = 6.4). Of the participants, 78% (n = 39) were admitted with a lower limb fracture and 88% (n = 44) reported having experienced at least one fall within the past year (Table 1).
Sample Characteristics (N = 50)
Note. AMD = age-related macular degeneration; THR = total hip replacement.
Glasses not worn because of advanced AMD.
Twenty-four percent (n = 12) of the participants reported having been diagnosed with an age-related eye disease. All but 1 participant habitually wore prescription glasses for near tasks, distance tasks, or both. Just more than one-quarter of the participants did not have their glasses with them in the hospital until prompted by the investigator, and when examined, 85% (n = 41) had glasses that were in poor condition (dirty, scratched, ill fitting, or broken). Just under one-third of the participants reported that they had not had an eye examination within the past 2 yr (Table 1).
Acuity
Distance acuities of the sample measured under the recommended lighting condition ranged from 20/20 to 20/400 Snellen acuity (Table 2). The International Classification of Diseases and Related Health Problems, 10th Revision (ICD–10), was used to classify the vision impairment level of the participants (WHO, n.d.). The ICD–10 specifies four categories of vision impairment based on distance acuity: mild or no visual impairment (20/20–20/70), moderate visual impairment (20/70–20/200), severe visual impairment (20/200–20/400), and blindness (<20/400 to no light perception). The last three categories—moderate vision impairment, severe vision impairment, and blindness—denote low vision. Table 2 shows the distribution of the sample across the four ICD–10 categories. Forty-six participants (92%) had acuities within the mild or no visual impairment range, including the 6 participants who were tested without their eyeglasses. One participant had moderate impairment, 2 had severe impairment, and 1 was classified as blind. Each of the 4 participants classified as having low vision also reported having an eye disease. Reading acuity ranged from 20/25 to <20/400 Snellen acuity for 49 of the 50 participants; 1 participant could not undergo this test because of illiteracy. Twenty-nine participants (59.2%) had reading acuities between 20/20 and 20/25, indicating that they should be able to easily read standard-size (1M) print and smaller. Fifteen participants (30.6%) had reading acuities between 20/32 and 20/50 inclusive, which enabled them to read standard-size print but limited their ability to read smaller print, and 5 (10.2%) had reading acuities within the low vision range, which limited their ability to read standard-size print. Results of the Wilcoxon test showed that participants demonstrated significantly better visual acuity under the recommended lighting condition for distance acuity (Z = 4.357, p = .000) and reading acuity (Z = 4.356, p = .000) than when tested under the typical lighting conditions of the clinic.
Range of Vision Impairment for Distance Acuity
Note. ICD–10 = International Statistical Classification of Diseases and Related Health Problems, 10th Revision (World Health Organization, n.d.).
Six participants were tested without their prescribed glasses.
Contrast Sensitivity
Of the sample, 72% (n = 36) had intact CSF and would be expected to perform adequately in most environments. The remaining 28% (n = 14) were at increased risk of experiencing at least some difficulty in detecting low-contrast features in the environment and required increased illumination and contrast to detect important environmental features (Table 3).
Contrast Sensitivity Function
Note. N = 50. CSF = contrast sensitivity function.
Discussion
We found that most patients referred for occupational therapy services on the orthopedic unit had normal-range distance acuity on screening, and only a small percentage (8%) had visual acuities in the low vision range. However, nearly one-third (28%) of the participants displayed impaired low-contrast acuity. On the basis of their reading acuity, almost one-third of the sample (31%) were likely to experience difficulty reading small print and a further 10% would not be able to read standard-size print.
The visual changes in these participants could potentially contribute to limitations in completing everyday activities with small or low-contrast detail, such as grooming, medication management, cooking, shopping, and financial management (Owsley, McGwin, Sloane, Stalvey, & Wells, 2001); these changes also place them at increased risk of falls when they return home. The incidence of impaired vision among the older adults referred to occupational therapy with non–vision-related diagnoses in this study highlights the need for generalist occupational therapists to have at least a basic understanding of how to screen for vision impairment and recognize and address its impact on occupational performance. However, a recent survey of generalist occupational therapy practitioners in the United States found that only half of the respondents perceived that their occupational therapy education had adequately prepared them to work with adults with vision impairment (Winner et al., 2014).
In addition, although 98% of participants habitually wore glasses, nearly a quarter did not have their prescribed glasses in the hospital until prompted, a figure similar to that found by Lotery et al. (2000) when assessing patients admitted to a rehabilitation floor. Unlike Medicare, which covers an annual eye exam but does not cover the cost of eyeglasses, the Irish national health care system pays for an eye exam every 2 yr and provides glasses to holders of a medical card (Association of Optometrists Ireland, n.d.). Of the participants in this study, 90% were medical card holders and entitled to this benefit. Yet, one-third had not had an eye examination within the previous 2 yr, and 85% had glasses in poor repair. This finding suggests that other factors may have influenced the utilization of eye care services in the study population. An examination of World Health Surveys from 70 countries revealed three factors independently related to eye care utilization in the past year, regardless of the income status of the country: People with lower education, those living in rural areas, and men were less likely to avail themselves of an eye examination (Vela et al., 2012).
The significant difference between visual acuity scores obtained under typical hospital lighting and under recommended lighting has important implications for assessment and intervention. Adding task lighting to ensure that the acuity charts were fully illuminated improved the acuity of 23 of the 25 participants retested under this condition. This finding highlights the importance of ensuring that acuity charts are properly illuminated during testing. However, it also raises the issue of how lighting might affect the functional visual performance of older adults in typical hospital environments. A longitudinal study of vision changes in older adults without eye disease found that even those with normal visual acuity required much greater lighting and contrast than younger adults to clearly see details (Brabyn et al., 2001). Yet the presence of task lighting (e.g., gooseneck task lamps) is a rare feature in most hospital treatment and patient rooms, despite the fact that these are the environments in which patients are expected to perform ADLs and are assessed for their cognitive ability to return home.
The finding also raises a concern regarding the accuracy of results obtained in assessments containing small visual details when administered without prior knowledge of the clients’ visual status and without due consideration of the suitability and condition of the clients’ glasses and of the environmental lighting. Several studies with normally sighted older adults have found associations between reduced visual acuity and CSF and poorer performance on cognitive tests that include visual tasks (Bertone, Bettinelli, & Faubert, 2007; Hunt & Bassi, 2010; Skeel, Schutte, van Voorst, & Nagra, 2006; Wood et al., 2010). Bertone et al. (2007), for example, found that a minimal visual acuity loss (20/40) significantly and negatively affected performance on a variety of commonly used neuropsychological tests.
Most of the study participants had visual acuity within the normal range, but that does not mean that their acuity was corrected to the optimal level possible. Many older adults benefit from an eye exam and updated refractive correction. One in 4 people older than age 75 yr in a U.K.-based study had visual impairment owing to refractive error (Evans, Fletcher, & Wormald, 2004). Lotery et al. (2000) found that 14% of patients on a stroke rehabilitation unit had correctable visual impairment. Cox et al. (2005a) found that 21% of patients admitted with a fractured neck of the femur had not had contact with optometry or ophthalmology services in the preceding 3 yr; more than half of this group of patients had visual impairment, 27% of which was due to uncorrected refractive error and 31% to untreated cataract. Treating uncorrected refractive error, through the dispensing of glasses, magnifiers, or both, can improve quality of life and decreased symptoms of depression in older adults (Coleman, Yu, Keeler, & Mangione, 2006; Owsley et al., 2007).
Implications for Occupational Therapy Practice
The results of this study have the following implications for occupational therapy practice:
Vision loss is a common comorbidity in older adults. Occupational therapy practitioners should have an understanding of normal age-related changes in vision and age-related eye disease, strategies to enhance the use of vision, and the procedure to obtain an optometry or ophthalmology consult.
Many clients leave their glasses at home when admitted to the hospital. It is imperative that clients wear their glasses when undergoing assessments. An absence of glasses should be noted and taken into account when interpreting the outcome of assessments that contain low contrast and small details.
The condition of clients’ glasses should be inspected regularly, and they should be cleaned appropriately to ensure optimal use of the glasses.
Occupational therapy practitioners should consider the available lighting for the client and supplement with task lighting, as needed, to ensure optimal lighting in both clinical settings and home environments.
Screening visual acuity and contrast sensitivity and inspecting clients’ glasses should be included in the occupational therapy evaluation of older adults. It is important to complete these assessments before administering cognitive or neuropsychological tests with visual details, and it should also be considered when assessing clients who have a history of falls. If screening assessments suggest vision impairment, the occupational therapist should refer the client to an eye care professional for diagnosis and treatment.
Acuity charts must be properly illuminated to obtain accurate results.
When visual deficits are noted, the occupational therapist should liaise directly with the members of the rehabilitation team, advising them of the implications of such deficits on assessments, interventions, ambulation, and ADLs.
Occupational therapy practitioners can play an important role as educators, informing other health care professionals of the issues relating to vision loss and encouraging clients to schedule regular eye examinations.
Limitations and Future Research
Study limitations included a small convenience sample with a limited gender mix (18% male, 82% female); this ratio, however, was in proportion to the overall number of men and women referred for occupational therapy within the timeframe of this study (21.7% male, 78.3% female). In addition, the acuity results do not reflect a precise measurement of the participants’ best-corrected visual acuity: Screening rather than diagnostic acuity charts were used, the luminance level in the testing environment was not measured, and whether the level of lighting conformed to the standards outlined by the Consilium Ophthamologicum Universale (1984) is not known; not all of the participants had their glasses with them during testing, and one-third of the participants had not had an eye examination within the past 2 yr and may have been using an outdated refractive prescription. The acuity scores obtained, however, were an indication of the functional vision of these participants.
This study provides valuable new information for occupational therapists regarding the visual status of older adults admitted to the hospital for non–vision-related reasons and how their visual status can be affected by hospital lighting conditions. Further research examining the visual status of older adults referred to occupational therapy for non–vision-related reasons would help to determine the prevalence of vision impairment within the general rehabilitation population. It would also identify the level of knowledge that the generalist occupational therapy practitioner should possess about age-related vision impairment, appropriate screening assessments, and interventions, and it would highlight the importance of vision screening as a component of the occupational therapy evaluation. Such research should investigate the impact of reduced vision on one’s ability to complete functional tasks in a timely and safe manner and examine the effect of lighting conditions in hospital and home environments.