Full text of DOI:10.1093/gerona/56.9.M548

Journal of Gerontology: MEDICAL SCIENCES
001, Vol. 56A, No. 9, M548–M551
Copyright 2001 by The Gerontological Society of America
2
Prevalance of Functional Blindness, Visual
Impairment, and Related Functional Deficits Among
Elderly Mexican Americans
Anthony R. DiNuzzo,1,2 Sandra A. Black,2,3 Michael J. Lichtenstein,4,5 and Kyriakos S. Markides1,2
1
2
3
Department of Preventive Medicine and Community Health, Center on Aging, and Department of Internal Medicine,
University of Texas Medical Branch, Galveston.
4
Division of Geriatrics and Gerontology, Department of Medicine, University of Texas Health Science Center, San Antonio.
5Geriatric Research and Education Clinical Center, South Texas Veterans Health System, Audie L. Murphy Division,
San Antonio.
Background. This report describes the prevalence and correlates of functional blindness and visual impairment
among older Mexican Americans, using data on 2800 respondents from the Hispanic Established Populations for the Ep-
idemiological Study of the Elderly.
Methods. Bivariate and multivariate logistic regression analyses were used to examine the associations between cor-
rected bilateral distant vision and sociodemographic characteristics, selected health conditions, self-reported health sta-
tus, health care utilization, and functional dependence on the basis of assistance needed for basic and instrumental
activities of daily living (ADLs).
Results. Using a modified Snellen test for distance visual acuity, 5% of older Mexican Americans were found to be
functionally blind, and 13.5% were found to be visually impaired. Vision loss was significantly associated with older
age, lower education, hypertension, diabetes, poor self-rated health, and hospitalization during the year prior to the inter-
view. Over 50% of functionally blind subjects required assistance with at least one basic ADL, compared with 15% of
those who were visually impaired and 8% of those who were not visually impaired.
Conclusions. The prevalence of functional blindness in this sample of elderly Mexican Americans was higher than
reported for the general elderly population, yet they also have higher rates of adequate vision because of the low preva-
lence of visual impairment. The results suggest a need for more research on the prevalence and impact of functional
blindness and visual impairment on the health of older Mexican Americans.
ISUAL impairment, one of the most common condi-
tions affecting older adults, is a leading cause of func-
for elderly Hispanics, and no data are available for Hispan-
ics over 74 years of age, the age range in which visual im-
pairment is most prevalent.
The present study examines the extent of functional
blindness and visual impairment among older Mexican
Americans, as well as demographic and health correlates,
using data from the Hispanic Established Population for Ep-
idemiological Studies of the Elderly (HEPESE).
V
tional disability (1,2) and diminished quality of life (3). It is
well accepted that visual impairment becomes more preva-
lent with increasing age (4,5) and can adversely affect basic
and instrumental activities of daily living (ADLs). Other
risk factors associated with visual impairment include occu-
pational exposure to sunlight, cigarette smoking (6), alcohol
consumption (7), and low socioeconomic status (8).
A number of population-based studies have provided de-
tailed estimates of the prevalence, risk factors, and conse-
quences of vision problems among older adults (4,9–11).
Among the general population aged 65 and older, the preva-
lence of functional blindness (visual acuity worse than 20/
METHODS
Sample
The HEPESE is the latest in a series of large-scale epide-
miologic studies conducted throughout the United States,
funded by the National Institute on Aging. The initial wave
of the HEPESE was conducted during 1993 and 1994 in
Texas, Colorado, Arizona, New Mexico, and California,
with fieldwork conducted by Harris Interactive, Inc. Area
probability sampling was used to select a total of 3050 Mex-
ican Americans aged 65 and older (86% response rate). For
a more detailed description of the sampling procedure, see
Black and colleagues (13). The present study describes vi-
sual acuity for 2800 subjects. Data were not available for
250 subjects who were interviewed by proxy, refused visual
2
00) ranges from 1% to 4%, with an additional 10% to 14%
having visual impairment (visual acuity 20/50–20/200).
Relatively few studies, however, have examined visual acu-
ity among Hispanic populations. Data from the Hispanic
Health and Nutrition Examination Survey in the early
1
980’s suggested that Hispanics may have a lower preva-
lence of impaired vision compared with non-Hispanic
whites (12), with Mexican Americans experiencing severe
to mild visual impairment ranging from 5% to 12%. How-
ever, these studies have been limited by small sample sizes
M548

VISUAL IMPAIRMENT IN MEXICAN AMERICANS
M549
assessment, or were too ill or cognitively impaired to be
tested.
pared with nonhypertensive subjects (p ꢀ .05) or nondia-
betics (p ꢀ .001). Subjects taking insulin for their diabetes
were significantly more likely to be functionally blind or vi-
sually impaired than diabetics not taking insulin (p ꢀ .001).
Subjects reporting poor health status as well as those hospi-
talized overnight within the past year were more likely to be
functionally blind (p ꢀ .05). Table 1 shows the results of lo-
gistic regressions assessing the risk of functional blindness
and visual impairment associated with age, gender, educa-
tion, diabetes, and hypertension. Initial analyses indicated
that functional blindness and visual impairment were strongly
associated with increasing age. With the inclusion of physi-
cian-diagnosed hypertension and diabetes, age and diabetes
were found to be significantly associated with both func-
tional blindness and visual impairment.
Table 2 shows the rates of disabilities across vision cate-
gories. Subjects who were functionally blind were much
more likely than other subjects to have both ADL and IADL
disabilities. Respondents with visual impairment did not
have rates of ADL disability significantly higher than those
with adequate vision, although the rates of IADL disability
were more comparable to the functionally blind.
Measures
Visual acuity was measured using both self-report and
performance-based assessment. Respondents who reported
being blind were not further tested for visual acuity. Cor-
rected bilateral distant visual acuity was assessed using a
modified Snellen test utilizing directional Es to estimate
acuity from 20/40 to 20/200 as described by Salive and col-
leagues (4). This method divides distance vision into three
categories: less than or equal to 20/40 designated as ade-
quate vision, greater than 20/40 to less than or equal to 20/
2
2
00 designated as visual impairment, and greater than 20/
00 designated as functional blindness.
Sociodemographic measures included respondents’ age,
gender, years of education, and total annual household income.
Health-related measures included self-reported health sta-
tus (poor, fair, good, or excellent), having an overnight hos-
pital stay within the year prior to interview, and having a
physician’s diagnosis of hypertension or diabetes. Subjects
reporting diabetes or hypertension were asked if they were
currently taking medication for these conditions.
To measure disability, basic ADLs and instrumental ac-
tivities of daily living (IADL) were assessed with a modi-
fied version of the Katz ADL and OARS IADL scales
DISCUSSION
The results of the present study suggest important differ-
ences in the prevalence of visual acuity among older Mexi-
can Americans in comparison to the general population. A
comparison of prevalence of functional blindness and visual
impairment reported by Salive and colleagues (4), presented
in Table 3, demonstrates these differences. Functional
blindness among Mexican Americans aged 71 or older is
considerably higher (8.2%) than that reported for other
EPESE sites (4.6%) for the same age range. In addition,
whereas the prevalence of functional blindness for all age
groups except those aged 85 years or older was higher in the
present study than previously reported, the prevalence of vi-
(
14,15), respectively.
Analyses
Mantel-Haenszel chi-square analyses were used to evalu-
ate differences in the prevalence of functional blindness and
visual impairment across all sociodemographic and health-
related measures. Logistic regression models were then con-
structed to assess the risk of functional blindness and visual
impairment, with adequate vision as the reference category.
Initial models examined the risk of functional blindness and
visual impairment across sociodemographic factors, fol-
lowed by models that added physician-diagnosed hyperten-
sion and diabetes. All analyses incorporated weights using
SAS (16) and design effects using SUDAAN (17).
Table 1. Multiple Logistic Regression Analysis Predicting
Functional Blindness or Vision Impairment for Older
Mexican Americans
RESULTS
Of the 2800 subjects assessed for visual acuity, 58% were
women and more than 65% were younger than 75 years of
age. The average level of education was only 4.9 years. Over
half the sample reported a total annual household income of
less than $10,000. Visual assessment results indicated that
Functional
Blindness vs
Visual
Impairment vs
Total Vision
Impairment vs
Adequate Vision Adequate Vision Adequate Vision
Age, y
6
7
5–70 (reference)
1–74
—
—
—
1
08 (4.9%) subjects were functionally blind, including 45 (7
2.3 (1.2–4.5)
7.7 (4.4–14.0)
15.2 (8.6–27.0)
14.5 (7.2–29.1)
1.0 (0.7–1.4)
1.6 (1.2–2.2)
2.9 (2.1–4.0)
4.5 (3.0–6.7)
1.2 (0.9–1.6)
2.3 (1.8–3.0)
4.3 (3.2–5.8)
5.6 (3.9–8.1)
by proxy) who reported that they were blind. A total of 294
75–79
80–84
(
13.5%) subjects were considered to be visually impaired.
Functional blindness increased significantly with age from
8
5ꢁ
Gender
Women
1.4% in subjects 65 to 70 years old to 12.4% in subjects 85 or
1.2 (0.8–1.7)
1.3 (1.0–1.6)
1.2 (1.0–1.5)
older (p ꢀ .001). Visual impairment also increased with age,
ranging from 10.4% in subjects 71 to 74 years old to 31% in
subjects 85 and older. An inverse relationship for education and
visual impairment was evident, with significantly more visual
impairment among subjects with lower education (p ꢀ .01).
More than 5% of subjects with hypertension and 9% with
diabetes were functionally blind and significantly more
likely to be functionally blind or visually impaired com-
Education, y
ꢂ11 (reference)
6–11
—
—
—
0.4 (0.2–0.8)
0.6 (0.4–1.0)
1.0 (0.6–1.5)
1.4 (0.9–2.1)
0.7 (0.5–1.1)
1.1 (0.8–1.5)
ꢀ6
Health Condition
Hypertension
Diabetes
1.1 (0.7–1.6)
3.2 (2.1–4.7)
1.3 (1.0–1.7)
1.5 (1.1–2.0)
1.2 (1.0–1.5)
1.9 (1.5–2.3)
Note: Values are odds ratios (95% confidence).

M550
DINUZZO ET AL.
Table 2. Percentage of Frequency of Assistance Needed for Activities of Daily Living (ADL) and Instrumental Activities of Daily
Living (IADL) Among Older Mexican Americans Who Are Functionally Blind, Visually Impaired or With Adequate Vision
(
Weighted Percentages)
Total Sample
Functionally Blind
Visually Impaired
Adequate Vision
(n ꢃ 3050)
(n ꢃ 108)
(n ꢃ 294)
(n ꢃ 2398)
Assistance With at Least One ADL*
Assistance With at least One IADL*
Activities of Daily Living
Walk across small room
Bathing (sponge, tub, shower)
Person grooming
Dressing
Eating
Transfer from bed to chair
Toileting
13.6
56.0
50.7
89.5
14.6
70.9
8.1
49.0
9.1
10.8
6.7
8.6
4.5
36.9
38.6
27.6
35.7
17.2
30.1
23.7
8.8
12.9
5.0
7.3
3.0
4.5
5.5
2.7
4.2
1.7
4.3
2.8
7.9
5.7
5.2
3.8
Instrumental Activities of Daily Living
Telephone use
Drive car/travel alone
Shopping
Prepare own meals
Light housework
Heavy housework
Take medicine
11.3
39.3
22.6
14.0
15.4
43.9
9.5
12.3
25.1
28.9
52.0
84.2
70.0
58.9
51.7
80.9
45.4
51.3
55.9
72.4
11.1
57.2
30.6
16.0
17.3
56.1
8.4
14.5
31.2
34.8
5.5
30.6
14.6
6.9
9.2
36.4
4.4
6.0
19.0
22.1
Handle/manage money
Walk up/down stairs
Walk 1/2 mile
2
*
All comparisons were significantly different at p ꢀ .001; Mantel-Haenszel ꢄ statistic.
sual impairment was much lower. As a result, adequate vi-
sion was more common in this group than in the general
elderly population.
The risk of functional blindness associated with increas-
ing age was very evident in the present study. Mexican
Americans 85 years of age and over were at 10 times the
risk of becoming blind as those aged 65 to 70. In contrast,
the risk of visual impairment associated with increasing age
was much lower than the risk of functional blindness, a
finding that is consistent with other EPESE findings (4).
The influence of diabetes on functional blindness and vi-
sual impairment found in this sample of older Mexican
Americans was also consistent with previous studies (4).
Older Mexican Americans have been shown to have a higher
prevalence of diabetes compared with the general population
(18), with a higher prevalence of retinopathy compared with
non-Hispanic diabetics (12), which could have a direct effect
on the prevalence of functional blindness.
The inverse relationship found for education and impair-
ment in this study was similar to that found among older non-
Hispanics in the other EPESE studies (4). No relationship
was found in this study for prevalence of functional blindness
or visual impairment across other sociodemographic vari-
ables, including gender and level of income, results consis-
tent with most previous reports; however, there are some ex-
ceptions (4,9). The most common explanation for differences
in socioeconomical status and vision loss has been the eco-
nomic burden for those who are unable to afford medical
treatment to correct their vision loss. Because over 85% of
the subjects in the present study were eligible for Medicare, it
is possible that sufficient access to ophthalmologic care could
be a factor lessening the negative effect of lower income.
The association of functional blindness and visual im-
pairment with self-rated health was consistent with what
†
Table 3. Percentage of Best Functional Visual Acuity by Age: East Boston, New Haven, and Iowa EPESE (1988) Compared With
Hispanic EPESE (1993-94)
Blind or Worse Than 20/200
20/200 to ꢀ20/40
20/40 or Better
Age (y)
EPESE (n)
HEPESE (n)
EPESE (%)
HEPESE (%)
EPESE (%)
HEPESE (%)
EPESE (%)
HEPESE (%)
6
7
7
8
8
5–70
1–74
5–79
0–84
5ꢁ
—
1319
568
454
305
154
—
1.0
3.3
5.3
12.9
4.6
1.4
3.0
9.0
14.5
12.4
8.2
—
10.4
10.4
14.9
22.6
31.0
16.4
—
88.3
86.6
76.1
63.0
56.6
75.4
1440
1885
1152
858
15.6
25.8
35.2
47.6
28.6
83.6
70.9
59.5
39.6
66.8
Total (age 71ꢁ)
5335
1481
Note: EPESE ꢃ Established Populations for Epidemiologic Studies of the Elderly; HEPESE ꢃ Hispanic EPESE.
†
Source: Salive and colleagues (7).

VISUAL IMPAIRMENT IN MEXICAN AMERICANS
M551
was found at other EPESE sites (4). After controlling for
age, subjects in poorer health were significantly more likely
to be functionally blind. It is possible that declining health
could be correlated with loss of vision as a function of the
physiologic changes associated with normal aging.
Overall, subjects with functional blindness reported much
higher rates of ADL and IADL disability compared with
subjects who were visually impaired or who had adequate
vision. This level of disability among functionally blind
subjects can have important clinical implications among
older adults, requiring interventions and adaptive strategies
to lessen the negative impact of the loss of independence.
In summary, this study provides added insight into the
prevalence and risk of functional blindness and visual im-
pairment among older Mexican Americans. Whereas many
findings were consistent with previous studies, several dif-
ferences were found that warrant further investigation.
AM. Functional blindness and visual impairment in older adults from
three communities. Ophthalmology. 1992;99:1840–1847.
. Carter TL. Age-related vision changes: a primary care guide. Geriat-
rics. 1994;49:37–47.
. Hirvelä H. Prevalence and risk factors of lens opacities in the elderly in
Finland: a population-based study. Ophthalmology. 1995;102:108–117.
. Mergler D, Blain L, Lemaire J, Lalande F. Colour vision impairment
and alcohol consumption. Neurotoxicol Teratol. 1988;10:255–260.
. Tielsch JM, Sommer A, Katz J. Socioeconomic status and visual im-
pairment among urban Americans. Arch Ophthalmol. 1991;109:637–
641.
9. Tielsch JM, Sommer A, Witt K. Blindness and visual impairment in an
American urban population: The Balimore Eye Survey. Arch Ophthal-
mol. 1990;108:286–290.
0. West SK, Munoz B, Rubin GS, et al. Function and visual impairment
in a population-based study of older adults: the SEE project. Invest
Ophthalmol Vis Sci. 1997;38:72–82.
1. Salive ME, Guralnik J, Glynn RJ, Christen W, Wallace RB, Ostfeld
AM. Association of visual impairment with mobility and physical
function. J Am Geriatr Soc. 1994;24:287–292.
2. Lee DL, Gomez-Marin O, Lam BL. Prevalence of uncorrected binocu-
lar distance visual acuity in Hispanic and non-Hispanic adults.
Ophthalmology. 1997;105:552–560.
3. Black SA, Markides KS, Miller TQ. Correlates of depressive symp-
tomatology among older community-dwelling Mexican Americans:
the Hispanic EPESE. J Gerontol Soc Sci. 1998;53B:S198–S208.
4. Katz SC, Ford AB, Moskowitz RW, Jackson BA, Jaffe MW. Studies
of illness in the aged: the index of ADL, a standardized measure of bi-
ological and psychosocial function. JAMA. 1963;185:914–919.
5
6
7
8
1
1
1
1
1
Acknowledgments
This research was supported by the National Institute on Aging Grant
AG10939; the National Institute of Diabetes, Digestive, and Kidney Dis-
eases, Grant DK51261A; and the University of Texas Medical Branch
Claude Pepper Older Americans Independence Center, Grant NIH-
P60A617231.
Address correspondence to Kyriakos S. Markides, PhD, Department of
Preventive Medicine and Community Health, University of Texas Medical
Branch, Galveston, TX 77555-1153. E-mail: kmarkide@utmb.edu
15. Fillenbaum GG. Screening the elderly: a brief instrumental activities
of daily living measure. J Am Geriatr Soc. 1985;33:698–706.
16. SAS Institute. SAS/STAT User’s Guide, Version 6, 4th ed. Cary, NC:
SAS Institute, Inc; 1994.
1
7. Shah BV. SUDAAN User’s Manual, Release 6.34. Research Triangle
Park, NC: Research Triangle Institute; 1998.
References
1
2
3
4
. Rovner BW, Ganguli M. Depression and disability associated with im-
paired vision: the MoVIES project. J Am Geriatr Soc. 1998;46:617–
1
8. Black SA, Ray LA, Markides KA. The prevalence and health burden
of self-reported diabetes in older Mexican Americans: findings from
the Hispanic Established Populations for Epidemiologic Studies of the
Elderly. Am J Public Health. 1999;89:546–552.
6
19.
. Reuben DB, Silbey M, Damesyn M, Moore AA, Greendale GA. The
prognostic value of sensory impairment in older persons. J Am Geriatr
Soc. 1999;47:930–935.
. Branch LG, Horowitz A, Carr C. The implications for everyday life of
incident self-reported visual decline among people over age 65 living
in the community. Gerontologist. 1989;29:359–365.
Received March 21, 2000
Accepted July 24, 2000
Decision Editor: John E. Morley, MB, BCh
. Salive ME, Guralnick J, Christen W, Glynn RJ, Colsher P, Ostfeld