Age and Ageing 2003; 32: 643–649
Age and Ageing Vol. 32 No. 6  British Geriatrics Society 2003; all rights reserved
Comparison of balance in older people
with and without visual impairment
HARRY K. M. LEE, RHONDA J. SCUDDS
Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
Address correspondence to: H. K. M. Lee, Physiotherapy Department, Tung Wah Group of Hospitals, Jockey Club
Rehabilitation Complex, Aberdeen, Hong Kong. Fax: ( + 852) 2554 6078. Email: [email protected] or Rhonda
Scudds, Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Fax: ( + 852) 2764 1435. Email: [email protected]
Abstract
Objective: a cross-sectional study was used to compare the balance ability of older people with and without visual
impairment.
Setting: Tung Wah Group of Hospitals Jockey Club Rehabilitation Complex and the Pok Oi Hospital Jockey Club
care and attention homes for aged individuals.
Subjects: a total of 66 subjects, 65 years of age and older were divided into three groups based on their degree of visual impairment.
Methods: the directional Es chart was used to test the subjects’ visual acuity. Functional balance ability was measured
using the Berg balance scale. Demographic characteristics and baseline variables such as lower extremity range of
motion, muscle strength, and joint pain was assessed and compared between the groups.
Results: 66 older adults (43 women, 23 men) aged 69–94 years of age participated in the study. The one-way
ANOVA showed that the mean Berg balance scores were signiWcantly different (F(2,63) = 19.19, P < 0.001). Post hoc
tests showed that the group with no visual impairment had higher mean balance scores than the group with mild visual
impairment (P = 0.04) and those with moderate visual impairment (P < 0.001). The balance scores for the group with
mild visual impairment were also shown to be signiWcantly difference from those of the group with moderate visual
impairment (P = 0.003). Control of factors related to balance, such as range of motion, pain and strength, did not affect
the analysis of variance analyses.
Conclusions: balance was shown to be more impaired with greater visual impairment, which could result in falls and
resultant injury. The Wndings suggest that early intervention to improve visual acuity in older people may be important.
Keywords: visual impairment, visual acuity, functional balance ability
Introduction
Balance is required for maintaining a position, remaining stable while moving from one position to another,
performing activities of daily living, and moving freely.
However, a decline in balance ability has been shown to
occur with increasing age [1–4]. Bogle and Newton [5]
found that impaired balance was correlated with an
increased risk of falls and an increased mortality rate in
older persons who were prone to fall when compared
with those who were not prone to fall. Moreover, postural disturbances frequently result in falls and may consequently lead to negative consequences, such as
injuries and mortality, especially in the older population
[6–9].
Several studies have identiWed visual impairment as a
contributing factor to the occurrence of falls in the elderly
[10–13]. It has been shown that vision plays an important
role in balance, mobility, and falls [14]. Older people with
blindness have demonstrated a higher rate of falls than
those with deafness or those with no visual and hearing
impairment [7]. Gaebler [15] showed that visual and hearing impairment was related to the frequency of falls. There
is a high prevalence of low vision in older patients who
were admitted to an acute geriatric unit with falls, as well
as in older people who attend outpatient clinics [16, 17].
A large study of older residents of three communities
showed that limitations in mobility, activities of daily living, and physical performance were associated with
worse visual function [18]. More recently, the standing
balance in older persons in nursing homes, as measured
by amount of sway, was shown to be worse for those
who have visual impairment [19]. Also, a longitudinal
study demonstrated that the balance skills were lower
643
H. K. M. Lee, R. J. Scudds
among subjects who were legally blind than among those
with minimal sight [20]. However, the seven subjects
with minimal sight who participated in this study did not
have their vision measured objectively.
All of these studies in some way assessed the effect
that vision has on balance, however, few stated that visual
impairment was assessed in an objective manner and not
all used balance tests that were functionally relevant.
Apart from vision, several intrinsic factors have been
shown to be related to balance control in the older adults.
These included age, sex, height, body mass index, muscle
strength, range of motion, endurance and pain [9, 12, 21–27].
However, it was not known to what extent limited range
of motion contributes to instability in older people [8, 21].
Severe chronic diseases, neurological conditions, middle
ear problems, postural hypotension, side effects of medications, abnormal mental status and fear of falling have
also been shown to be factors related to balance control
[21, 25, 26, 28, 29].
Although several studies support that balance ability
decreases with age and that older people with some visual
impairment have a higher rate of falls, little is known
about the balance ability in older people with different
levels of visual impairment. The purpose of this study
was to compare the balance ability in older people with
no visual impairment, mild visual impairment and moderate
visual impairment.
verbally relayed to them in the event that they were illiterate or unable to see well enough to read the letter. All
participants signed or made a mark on the consent form
prior to participating in the study. The study was
approved by the ethics review board of the Hong Kong
Polytechnic University and the superintendents of the
participating care and attention homes.
Measurement
All of the measurements were taken in the afternoons at
approximately the same time of the day. They were
administered by one experienced physiotherapist in a
quiet, bright examination room. Information on gender,
age, type of walking aid, and the cause of the visual problem for those with visual impairment, as documented on
the medical examination report, was determined. The
subject’s weight and height was also measured.
Visual acuity and balance ability was then measured.
The directional Es chart was used to assess visual acuity
(Figure 1)[30]. This test is not literacy-dependent and is
widely used in China or with people who are illiterate
[30]. The directional Es chart examines central vision in
both eyes at the same time as the bilateral visual function
[18, 31]. The E chart has been used as a standardised test
for the measurement of visual acuity [18, 32–36]. The test
was carried out with the subjects seated and the chart set
at the subject’s eye level Wve meters away. The subject
was asked to determine the location of the open end of
Methods
Subjects
Sixty-six older adults volunteered to participate in the
study. A convenience sample was used and all the subjects who volunteered lived in one of six care and attention homes for aged individuals in the Jockey Club
Rehabilitation Complex or the Pok Oi Hospital Jockey
Club care and attention homes for aged individuals. Care
and attention homes provide residence to older adults
who cannot live independently in the community, but are
not bed-ridden.
The inclusion criteria included subjects who were 65
years of age or older and able to follow simple directions,
for example, left, right, up or down. The exclusion criteria
included people with functional blindness (acuity level
worse than 20/200) and those with major chronic medical
or physical conditions, including rheumatoid arthritis or
osteoarthritis, severe low back pain, severe lower limb
deformities, as diagnosed by a physician, which resulted in
the inability to ambulate independently or with the use of
an assistive device. Those who were non-ambulatory, had
an amputation or had been diagnosed with Parkinson’s
disease, stroke, severe dementia or vestibular problems, as
well as those with poor memory were also excluded.
All eligible subjects were provided with a letter of
information describing the study or the information was
644
Figure 1. Directional Es chart (note: the size of the chart is
not to scale) [30].
Balance and visual impairment in older adults
the letter E on the largest, top line. If the answers were
correct, the subject was required to read the next
smaller line until the smallest line was reached. The
directional Es chart consisted of 12 lines. The visual
acuity was scored as 0.1 if the subject could only determine the direction of the E on the Wrst line and 1.0 if
the subject could correctly see the tenth line. If the
subject could read the whole eighth line, but could read
less than one half of the ninth line, then visual acuity
was 0.8. When a subject was unable to read the largest
line on the chart from a Wve meters distance, test
distance was shortened and a correction equation [0.1 × test
distance (in meters)/5] was used to calculate visual
acuity. Following the visual acuity test, the subjects
were classiWed into three groups according to the criteria
set in Table 1.
The Berg balance scale was used to assess the balance
ability of the subjects. It is a performance-based measure
of balance consisting of 14 observable tasks [37–39]. All
items are graded on a Wve-point ordinal scale (0–4
points), which give a total score ranging from 0–56
points. If the tasks required subjects to place the foot on
a stool or to reach forward, the choice of which leg to
stand on or how far to reach was decided by the subjects
[37]. The examiner was allowed to demonstrate the task
before the subject performed it. Ten of the subjects, with
different levels of visual impairment were asked to
complete the Berg balance test a second time, with the
same rater, within one week in order to calculate intrarater reliability.
Finally, the verbal numeric pain rating scale was
administered, followed by the muscle testing and
range of motion assessment. The verbal numeric pain
rating scale was used to assess present pain intensity of
the hip, knee and ankle. The scale ranged from zero
(no pain) to 10 (worst pain imaginable). A standard
goniometer was used to measure active range of
motion at the hip, knee, and ankle joints. Standard
methods [40] for measuring the joint range were used.
The total active range of motion (TAM) for a particular joint was the sum of the Xexion and extension
range.
A calibrated hand-held dynamometer, the Nicholas
manual muscle tester (MMT) model 01160 (Lafayette
Instrument Company, Lafayette, IN 47903, USA) was
used to test isometric muscle strength of the quadriceps,
Table 1. ClassiWcation of visual impairment [18, 31]
Group
Visual
(value in fraction)
Acuity
(value in decimal)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
No visual impairment
Mild visual
impairment
Moderate visual
impairment
Functional blindness
20/40 or better
20/60 or better but
worse than 20/40
20/200 or better but
worse than 20/60
Worse than 20/200
≥0.5
0.5 to ≥0.3
0.3 to ≥0.1
<0.1
hamstrings and ankle dorsiXexors for each leg using
standard techniques [41]. The MMT has a digital accuracy
of ± 0.5% of full scale and a force range from 0.0 to
199.9 kg [42]. Before the actual test, the subjects were
given a demonstration and one trial to familiarise
themselves with the required action. During the test, the
subject was instructed to raise the limb to a speciWc
height and maximally resist the examiner’s efforts to
depress it with the standard method and to hold it for
three seconds [43, 44]. Each muscle strength test was
repeated three times with a brief rest of one minute in
between and the highest value was recorded.
Statistical analysis
All analyses were carried out with the SPSS (Version 9.0)
statistical software package. The ICC (3, 1), using the
absolute agreement option, was calculated to determine
the intra-rater reliability for the Berg balance test [45].
The means and standard deviations of the balance scores
as well as the 95% conWdence intervals for the mean
differences in balance scores were calculated. A one-way
ANOVA was performed to determine if there were any
statistically signiWcant differences in mean Berg balance
scores between those with no visual impairment, mild
visual impairment and moderate visual impairment. Multiple comparisons, using Scheffe’s test, were used to
compare the balance scores between pairs of groups following a signiWcant ANOVA result. For each of the factors listed in the introduction that may inXuence
balance, an ANCOVA was performed to determine the
effect of each of them on the relationship between balance and vision. A signiWcance level for all statistical
tests was set at 0.05.
Results
A total of 10 subjects were invited to repeat the Berg
balance test measurements with the same rater within a
period of one week. The ICC (3, 1) for the intra-rater
reliability of the Berg balance test was calculated to be 0.97.
Demographic characteristics of the subjects
A total of 66 subjects, ranging in age from 69 to 94
years of age were recruited for the study, with 22
subjects in each of the three visual impairment
subgroups (Table 2). Forty-three subjects (65.2%) were
women and 23 subjects (34.8%) were men. The cause of
visual problems in the subjects included cataracts
(37.9%), glaucoma (10.6%), macular degeneration
(25.8%), retinal detachment (4.5%), and unknown
causes (22.2%). A similar proportion of the subjects
were able to walk without the help of an assistive device
(42%) or with a standard cane (44%). The remainder of
the subjects either used a quadruped cane or a walker
(14%) during ambulation.
645
H. K. M. Lee, R. J. Scudds
Table 2. Demographic characteristics of the study sample
Gender
(% female)
Group
Age (years)
Mean (SD)
Height (m)
Mean (SD)
Weight (kg)
Mean (SD)
BMI (kg/m2)
Mean (SD)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
No visual impairment (n = 22)
Mild visual impairment (n = 22)
Moderate visual impairment (n = 22)
(40.9)
(81.8)
(72.7)
77.27 (5.07)
79.95 (6.28)
83.59 (6.22)
Table 3. Mean total active movement (TAM) by group.
Joint
No visual
Mild visual
Moderate visual
impairment
impairment
impairment
Mean degree (SD) Mean degree (SD) Mean degree (SD)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hip
Right
Left
Knee
Right
Left
Ankle
Right
Left
107.23 (8.31)
107.82 (7.01)
102.73 (9.00)
98.50 (20.74)
99.77 (11.87)
97.95 (12.28)
136.09 (4.32)
129.82 (26.85)
130.32 (8.17)
129.73 (5.53)
128.95 (9.58)
130.00 (9.67)
44.59 (4.12)
44.45 (4.74)
39.68 (7.54)
40.68 (8.87)
40.68 (8.13)
38.45 (8.73)
Baseline measures
The descriptive statistics for the total active movement
(TAM) for each joint of the lower extremity in each
group are presented in Table 3. Those for isometric muscle strength for the knee Xexion, knee extension and
ankle dorsiXexion are presented in Table 4. Pain intensity
ratings for the hip, knee and ankle ranged from zero to a
maximum of four.
The Berg balance test
The mean Berg balance scores for the group with no visual impairment, the group with mild visual impairment
and the group with moderate visual impairment were
50.73 (SD = 3.41), 45.55 (SD = 6.85) and 38.59 (SD =
8.31), respectively (Figure 2). The result of the one-way
ANOVA showed that there was a signiWcant difference
1.58 (0.10)
1.53 (0.09)
1.49 (0.10)
59.96 (13.45)
54.96 (10.58)
50.96 (11.82)
23.81 (3.19)
23.48 (3.55)
22.94 (4.49)
in mean Berg balance scores between the three groups
(F(2, 63) = 19.19, P < 0.001). The results of the post hoc
Scheffé comparison tests revealed that there were signiWcant differences in the mean balance scores between the
group with normal vision and the group with mild visual
impairment (P = 0.04, mean difference = 5.18, 95% CI
0.25, 10.11), between the group with no visual impairment and the group with moderate visual impairment
(P < 0.001, mean difference = 12.14, 95% CI 7.21, 17.07)
and between the group with mild visual impairment and
the group with moderate visual impairment (P = 0.003,
mean difference = 6.95, 95% CI 2.03, 11.88).
Age, gender, body mass index, the summary scores
for the range of motion, the strength scores, and the pain
scores were entered into separate ANCOVA models.
After controlling for each individual factor, the same
conclusion as the original one-way ANOVA regarding
the difference in mean Berg balance scores resulted.
Discussion
This study provides evidence that level of visual acuity may
affect balance in older Chinese people who reside in care
and attention homes. These results are consistent with
other studies studying the effect role of vision on balance
in older people [7, 20]. Moreover, the results of this study
are supported by a cross-sectional and cohort study, which
reported that impaired visual function was associated with
poor scores on the physical performance measures, that is,
Table 4. Mean isometric muscle strength by group
Joint
No visual
impairment
Mean kg (SD)
Mild visual
impairment
Mean kg (SD)
Moderate visual
impairment
Mean kg (SD)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Knee extension
Right
11.45 (3.46)
Left
11.25 (4.27)
Knee Xexion
Right
5.99 (2.33)
Left
5.50 (2.50)
Ankle dorsiXexion
Right
5.67 (1.73)
Left
4.90 (1.63)
646
9.38 (4.59)
9.06 (4.07)
10.32 (4.14)
9.59 (3.88)
5.10 (2.77)
4.63 (2.22)
5.34 (3.01)
4.98 (2.99)
5.41 (2.84)
4.59 (2.28)
5.79 (3.27)
5.81 (3.24)
Figure 2. Boxplots for the Berg balance scores for the three
groups based on degree of visual impairment.
Balance and visual impairment in older adults
standing balance and walking scores [18]. The results of
the present study provide additional evidence that balance
abilities, measured using a functional instrument, decline
with a corresponding decline in visual function.
In the present study, it was observed, subjectively,
that older people with no visual impairment, performed
better and were more stable in some difWcult items of the
Berg balance test, for example, reaching an arm forward
while standing, placing alternate foot on step or stool
while standing unsupported, standing unsupported one
foot in front, and standing on one leg. This observation
was quite similar to that obtained by Berg and her
co-workers [37]. Berg et al. [37] showed that the most
difWcult items for older patients to perform successfully
were reaching an arm forward while standing, standing
on one leg, and standing unsupported with one foot in
front of the other. Therefore, it is likely that vision plays
an important role in balance. It has also been shown that
visual cues and visual information from the environment
are an important source of feedback for balance skills
[20, 27].
The scores obtained with the Berg balance scale
appear to be appropriate as a score of <45 was shown to
be predictive of multiple falls in older adults [46]. Thorbahn and Newton [47] also pointed out that this cut-off
score predicted a person’s use of an assistive device. In
the present study, impaired balance score was related to
the levels of visual impairment, and the result was consistent with the cut-off score of the above studies.
Furthermore, interventions such as exercise and balance training may be indicated in the visually impaired
older people. Studies using exercise interventions in older
people had shown improvement in balance, reaction
time, strength, and Xexibility [48, 49]. A recent research
also demonstrated a signiWcance of Tai Chi training in
elderly persons to reduce the risk of falls [50]. Therefore,
incorporating Tai Chi or other exercise interventions into
balance training programmes for older people with visual
impairment may be beneWcial.
The limitations of this study should be addressed.
The study was conWned to older volunteers living in care
and attention homes. In order to improve the generalisability of the results, further study with subjects from
more and different types of centres in Hong Kong or
from other ethnic groups is recommended. Also, a random sample of subjects should be selected from the participating centres.
Another limitation of this study was that only visual
acuity of the subjects was measured. Apart from visual
acuity, visual Weld, contrast sensitivity, depth perception,
and glare impairment should be included in the examination of vision for the subjects [22]. These additional factors may also be a factor associated with balance
performance. In addition, range of motion of the upper
extremity and trunk as well as muscle strength of, for
example, hip abduction, hip adduction, trunk Xexion and
extension, which were not tested in this study, should be
incorporated into future studies.
The Wndings of the present study suggest that early
intervention to improve the visual acuity of older people
who are at risk for falls may be important. A randomised
controlled trial study would need to be done to investigate whether early intervention to improve the visual
acuity of older people improves balance and reduces
falls. Assessing balance may have important implications
for improving the quality of rehabilitation services for
older people with visual impairment not only in care and
attention homes, but also for older people with visual
impairment living in other settings. Providing rehabilitation services aimed at maintaining or improving physical
function and balance may be important to consider,
especially for those older individuals with impaired
vision. Standardised functional measures should be
employed to assess not only balance, but also visual
impairment in the screening for potential fallers among
older people. Referrals to appropriate health care providers to treat or correct impaired vision, if possible, are
also recommended.
Key points
• The functional balance of three groups of older adults,
those with normal visual acuity, mild impairment in
visual acuity and moderate impairment in visual acuity,
were compared.
• Gender, age, height, and lower extremity range of
motion was shown to be signiWcantly different between
the three groups of older adults and, therefore, were
included as covariates in the analysis that examined differences in functional balance between the groups.
• Older people with moderate impairment in visual acuity were shown to have poorer functional balance compared with those with no or mild visual impairment.
Acknowledgements
The authors would like to express their gratitude to the
physical therapists who helped provide clients for this
study.
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Received 7 October 2002; accepted in revised form 2 June
2003
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