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Visual acuity outcomes after cataract extraction in Chinese Americans: the Chinese American Eye Study (CHES)
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Visual acuity outcomes after cataract extraction in Chinese Americans: the Chinese American Eye Study (CHES)
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Content
Visual Acuity Outcomes after Cataract
Extraction in Chinese Americans
The Chinese American Eye Study (CHES)
Yaorui Liu
May 2018
A thesis presented for the degree of
Master of Science in Applied Biostatistics & Epidemiology
Department of Preventive Medicine
Supervisor: Dr. Roberta McKean
Thesis Committee: Dr. Roberta McKean (Chair)
Dr. Meredith Franklin
Dr. Christianne Lane
UNIVERSITY OF SOUTHERN CALIFORNIA
1
Table of Contents
Abstract ................................................................................................................ 2
Introduction .......................................................................................................... 4
Patients and Methods ........................................................................................... 5
Definition of Lens Opacity .................................................................................... 6
Definition of Visual Impairment ............................................................................. 7
Determination of Cataract Extraction.................................................................... 8
Determination of Primary Causes of Visual Impairment ....................................... 8
Statistical Methods ............................................................................................... 8
Results ................................................................................................................. 9
Discussion .......................................................................................................... 12
List of Tables ...................................................................................................... 15
References ......................................................................................................... 19
2
Abstract
Purpose: To characterize the prevalence of visual impairment (VI) among adult
Chinese Americans with a history of cataract extraction and describe the primary
causes of visual impairment among adults with residual VI after cataract extraction.
Design: A population-based study of Chinese Americans age 50+ years
Participants: 454 participants in the Chinese American Eye Study (CHES) with
cataract extraction.
Method: Participants answered an in-home interview and completed a comprehensive
ophthalmologic examination. Visual impairment in the cataract-operated eye was
defined by 2 criteria: (1) presenting visual acuity where PVA of 20/40 or worse. (2) best-
corrected visual acuity where BCVA of 20/40 or worse. The severity of visual
impairment was classified by 4 levels: none (<20/40), mild (20/40-20/60), moderate
(20/80- 20/160) and severe (>20/160). Causes of visual impairment was determined by
ophthalmologists through a chart review.
Primary Outcome Measures: Prevalence of visual acuity among eyes with a history of
cataract extraction.
Results: Of the 4582 participants who had a clinical eye examination in CHES, 454
participants had a history of cataract extraction that was verified through the clinical eye
examination. Of the 454 participants, 151 (33%) had clinical evidence of a unilateral
cataract extraction (9 aphakic and 142 pseudophakic), and 303 (67%) participants had
bilateral cataract extractions (5 aphakic and 601 pseudophakic), resulting in a total of
757 cataract-operated eyes. The frequency of VI among cataract extracted eyes was
54.4% based on presenting visual acuity and 29.3% based on best corrected visual
acuity; the three most frequent causes of VI among the eyes with cataract extraction
were macular degeneration (51.2%), myopic retinopathy (14.5%) and primary open-
angle glaucoma (POAG) (10.7%)
Conclusion: A significant portion of participants with a history of cataract extraction had
residual VI among our population based sample of adult Chinese Americans (the two-
3
sided p-value of Fisher’s Exact Test =0.0047 in worse-seeing cataract-operated eye).
The frequency of VI was higher among aphakic participants than pseudophakic
participants. Approximately 25% of adults with presenting VI could be eliminated with
refractive correction, these data indicate the need of postoperative ophthalmologic
examinations for cataract-operated participants.
4
Introduction
Cataract is the most common eye disease found in older adults in the United States and
worldwide,
1-3
and is recognized as the most common cause of blindness and visual
impairment (VI) among older adults.
1-3
While VI and blindness due to cataracts are
typically treatable by surgical intervention, adults often live with some level of vision loss
due to cataracts for a number of years before they advance in development to become
severe enough to warrant extraction. The degree of residual VI among individuals with
cataract extraction in the general population has not been well characterized and not
previously described in a population-based sample of Chinese Americans. The causes
of VI and blindness among individuals with a history of cataract extraction, whether
residual VI is correctable through proper refraction, and how the distribution of causes
of VI and blindness compares to those of individuals in the same general population
without a history of cataract extraction are important to evaluate to better understand
the long-term benefits of cataract treatment.
Asian Americans are the fastest growing racial/ethnic group in the United States and
among this population, Chinese Americans represent the largest proportion.
4,5
According to data from the Census Bureau, between 2000 and 2010 the Asian
American population increased by 14.7 million (43.4%) accounting for 4.8% of the
United States population. While data on Non-Hispanic and Hispanic Whites has been
described in the literature previously
6-18
, the epidemiologic characteristics of visual
impairment after cataract extraction for Chinese American is not known. The degree of
visual impairment and the primary causes of visual impairment after cataract extraction
for Chinese Americans are important to quantify in order to better understand the long-
term impact of cataract surgery on visual impairment and the potential need for
additional corrective refraction.
The Chinese American Eye Study (CHES) is a population-based study designed to
characterize the prevalence of ocular diseases, lens opacities, visual impairment, and
5
blindness among Chinese American adults. The population includes adults age 50
years or older, residing in the city of Monterey Park in Los Angeles County, California at
the time of recruitment. The aim of this paper is to report the prevalence of visual
impairment after cataract extraction among Chinese American adults defined both by
presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) and identify the
primary causes of visual impairment after cataract extraction. Furthermore, we compare
the prevalence of visual impairment and primary causes of VI in Chinese American to
that of a similar population-based sample of Latinos also residing in Los Angeles
County (LALES) and assessed with an identical protocol.
19,20
We also list each
prevalence of several large population-based studies of VI outcomes after cataract
extraction in Asian population based on the WHO standard (<20/60 using presenting
visual acuity).
28-32
Collection of these data are necessary to understanding visual acuity
outcomes, the prevalence of visual impairment and the primary cause of visual
impairment after cataract extractions.
Patients and Methods
The study population was identified from a population-based, cross-sectional study of
Chinese Americans, aged 50 years and older residing in 15 census tracts in the city of
Monterey Park in Los Angeles County.
21
This area was selected because it included a
high proportion of Chinese American residents and was geographically near the Health
Science Campus of the University of Southern California. A door-to-door census was
completed to identify eligible participants. Each potential participant was informed
about the study protocol, potential risks and was asked to sign the study informed
consent form before enrolling in the study. The study protocol and informed consent
forms were reviewed and approved by the institutional review board of Medical Center
of the University of Southern California, and all study procedures are compliant with the
recommendations of the Declaration of Helsinki.
6
Each participant completed a detailed health interview with a trained field staff member.
An appointment was made to complete a clinical eye examination by our study
ophthalmologists and technicians in our community located clinical center. The home
interview included demographic data, behavioral, risk factors, history of ocular disease,
insurance status, measures of acculturation, and measures of health and vision-specific
quality of life. The clinical eye examinations followed a standardized data collection
procedure including measurements of visual acuity, intraocular pressure, visual fields,
fundus and optic disc photography, measurements of the anterior and posterior
segments, blood pressure, glycosylated hemoglobin, and blood glucose.
Vision was measured for each eye with presenting correction (if any) at 4 m using
standard Early Treatment Diabetic Retinopathy Study protocols with a modified distance
chart transilluminated with a chart illuminator (Precision Vision).
22
Presenting distance visual acuity (VA) was measured for the left eye, and the right eye
with existing refractive correction. If the participant could not read 55 letters at 4 m in
either eye (equivalent to Snellen fraction 20/20), an automated refraction was performed
using the Humphrey Automatic Refractor (Carl ZeissMeditec), followed by subjective
refraction. After refraction, the eye was retested to measure the best-corrected
VA(BCVA). If the participant was unable to read 20 letters at 4m (equivalent to Snellen
fraction 20/100), measurement and subjective refraction were performed at 1m. An LEA
chart was used for participants unable to read standard charts. The VA score was
calculated using the total number of letters read correctly by the participant and then
converted into logMAR chart.
23
Definition of Lens Opacity
Lens opacities were defined by using the LOCS II grading system.
24-26
All lens changes
included presence in either eye): (a) Any of gradable posterior subcapsular cataract
7
(PSC), nuclear, cortical lens opacity (LOCS II grade ≥2); or (b) lens opacities too
advanced to grade; or c) evidence of having undergone unilateral cataract extraction or
bilateral cataract extractions.
Any participant who had at least one type of lens opacity (LOCS II ≥ 2) was included in
the definition for each type of lens opacity present in either eye. Each participant was
categorized as having one or more types of a gradable opacity. Participants who
underwent unilateral cataract extraction were included in this definition if the
contralateral eye had gradable lens opacity. Participants who underwent bilateral
cataract extraction were excluded from this definition.
A participant was classified as either single lens opacity or mixed lens opacities. A
single opacity was defined as a participant had posterior subcapsular cataract (PSC)
only, or nuclear only, or cortical only in both eyes. Mixed opacities were defined as a
participant had more than one type of lens opacity. The 4 classifications (PSC only,
nuclear only, cortical only, and mixed) were mutually exclusive.
Definition of Visual Impairment
Visual impairment in the worse-seeing cataract-operated eye and any cataract-operated
eye was defined by 2 criteria: (1) presenting visual acuity (PVA) of 20/40 or worse. (2)
best-corrected visual acuity (BCVA) of 20/40 or worse. The severity of visual impairment
was classified using 4 levels: none (<20/40), mild (20/40-20/63), moderate (20/80-
20/160) and severe (>20/160).
Visual impairment in the worse-seeing cataract-operated eye was defined by two
criteria: (1) if a person had bilateral cataract extractions, then the eye with worse visual
acuity is the worse-seeing cataract-operated eye. (2) if a person had unilateral cataract
extraction, then the eye with cataract extraction is considered as the worse-seeing
8
cataract-operated eye. Both unilateral and bilateral cataract extractions contributed to
the “All” cataract operated eye definition.
Determination of Cataract Extraction
Cataract extraction is a clinical operation performed to remove a lens opacity from an
eye and may include the implantation of an artificial lens at the same time. Cataract
extraction status was derived from either clinical exanimation or in-home interview for all
participants.
Determination of Primary Causes of Visual Impairment
The primary causes of visual impairment were defined by standard clinical criteria. A
chart review of all clinical data including clinical examination findings, lens grading, and
fundus photographs was conducted by our designated ophthalmologist for each eye.
Uncorrected refractive error was defined as cataract-operated eye having visual
impairment when measured by presenting visual acuity (visual acuity > 20/40), but no
visual impairment when measured by best-corrected visual acuity (visual acuity <20/40).
Statistical Methods
The crude prevalence was calculated as the number of participants with visual
impairment in worse-seeing, cataract-operated eyes out of the total participants with
cataract-operated eyes. The worse-seeing cataract-operated eye was defined as 1) the
unilateral cataract-operated eye or 2) the worse-seeing eye for bilateral cataract
extractions. The prevalence was also calculated as the number of all cataracted
operated eyes with visual impairment out of the total cataract-operated eyes. All
cataract-operated eyes were defined as any eye with cataract extraction. The
prevalence of visual impairment (VI) was evaluated by constructing N*M tables where N
9
represents the status of cataract extraction (aphakic, pseudophakic) stratified by PVA
and BCVA, and M represents the severity of visual impairment (none, mild, moderate,
severe). For each table, a chi-square test was applied to evaluate the association
between visual impairment (none or any) and cataract extraction status (aphakic or
pseudophakic). Fisher’s exact test was applied if the cells have expected counts less
than 5. N*M Tables were also constructed to evaluate the primary causes of VI by the
severity (mild, moderate, severe) for the worse-seeing cataract-operated eye and all
cataract-operated eyes. VI was defined based on BCVA. Confidence intervals for
proportions were calculated using 𝑝 ± 𝑧 ∗ √
𝑝 ( 1 − 𝑝 )
𝑛 , where p is the sample proportion and
z* is 1.96 defined as the standard normal z-score. All analysis was performed using
SAS 9.4 and statistical significance was defined by an alpha-level of 0.05. Uncorrected
refractive error was calculated based on the difference between participants with visual
impairment when using presenting visual acuity (PVA of 20/40 or worse) compared to
visual impairment using best corrected visual acuity (BCVA of 20/40 or worse).
Results
Description of Study Cohort
Of the 4,582 participants who had a clinical examination in CHES, a total of 454
participants (9.9%) were confirmed to have a history of cataract extraction by clinical
eye examination. Of the 454 participants, 151 (33%) had a unilateral cataract extraction
(9 aphakic and 142 pseudophakic), and 303 (67%) participants had bilateral cataract
extractions (5 aphakic and 601 pseudophakic), resulting in a total of 757 cataract-
operated eyes.
Prevalence of Visual Impairment
Among the 454 participants with a history of cataract extraction, 247 (54.4%) had
residual visual impairment based on presenting visual acuity (PVA) in the worse-seeing
10
cataract-operated eye; this number was reduced to 133 (29.3%) participants with visual
impairment based on best-corrected visual acuity (BCVA) (Table 1). Across all the 3
severity groups (mild, moderate, severe), there was a higher proportion of visual
impairment defined by PVA when compared with visual impairment defined by BCVA
(mild: 30.4% vs. 18.1%, moderate: 15.9% vs. 4.9%, severe: 8.2% vs. 6.4%).
The prevalence of visual impairment defined by either PVA or BCVA was consistently
higher in the aphakic group compared to the pseudophakic group (PVA 100% vs.
53.5%; BCVA 88.9% vs. 28.1%). Further, the aphakic group had a larger proportion of
participants with severe visual impairment compared to the pseudophakic group based
on both PVA and BCVA (PVA 55.6% vs. 7.2%; BCVA 55.6% vs. 5.4%). The association
between visual impairment (none or any) and cataract extraction status (aphakic or
pseudophakic) in both worse-seeing cataract-operated eye and all cataract-operated
eyes were statistically significant (Fisher’s exact test p=0.0047 and p=0.0019,
P<0.0001).
When examining all 757 cataract-operated eyes (Table 2), 334 (44.1%) had visual
impairment defined by PVA, compared to 180 (23.8%) cataract-operated eyes defined
by BCVA. As expected, the prevalence of visual impairment in all 3 severity groups
(mild, moderate, severe) was higher when defined by PVA than the prevalence defined
by BCVA and visual impairment was most frequently defined as mild (PVA 26.8%,
BCVA 15.9%), followed by moderate (PVA 11.9%, BCVA 3.4%) and severe (PVA 5.4%,
BCVA 4.4%).
Causes of Visual Impairment
As shown in Table 3, the three most frequent causes of visual impairment after cataract
extraction in the worse-seeing eye were macular degeneration (46.5%), myopic
retinopathy (15.2%) and POAG (11.1%). Other causes of visual impairment included:
11
after-cataract Posterior Capsule Opacity (6.1%), proliferative diabetic retinopathy (PDR)
(4.0%), and macular cyst or hole (3.0%). Visual impairment due to optic nerve atrophy,
epiretinal membrane and retinal detachment collectively represented 2.0% of eyes,
while amblyopia, macular edema, Non-proliferative diabetic retinopathy (NPDR),
asteroid hyalosis, cornial scar/opacity, other retinal disorders, and primary angle closure
glaucoma accounted for 1.0% of eyes with visual impairment.
The most frequent causes of visual impairment in all cataract-operated eyes also were
macular degeneration (51.2%), myopic retinopathy (14.5%) and primary open angle
glaucoma (10.7%) (Table 4). The two most frequent secondary causes of visual
impairment for both worse-seeing cataract-operated eye and all cataract-operated eye
were primary open angle glaucoma (POAG) and macular degeneration (data not
shown).
Comparison with LALES and other studies
The prevalence of visual impairment based on presenting visual acuity in the worse
seeing, cataract-operated eye was higher in the Los Angeles Latino Eye Study (LALES)
compared to CHES for each 10-year age group (50-59, 60-69, 70-79) with the exception
of the oldest (80+) age category (Table 5). For age groups 50-59, 60-69, and 70-79, the
prevalence of visual impairment in the LALES population was 15%, 19%, and 8% higher
respectively compared to CHES. However, the prevalence of visual impairment in
CHES participants with cataract-operated eyes was 68.7% compared to 60.7% in
LALES. The age-standardized prevalence of visual impairment was higher in LALES
(56%) compared to CHES (43%).
Table 6 shows the prevalence of visual impairment in all cataract-extracted eyes based
on the World Health Organization (WHO) definition of visual impairment using
presenting visual acuity for CHES, LALES, and 5 other population-based studies of
12
Chinese adults in Asia. The prevalence of VI for CHES is similar or lower than the
prevalence reported for other Chinese adults in Asia, however the frequencies reported
are not age-standardized or restricted to the same age range.
Discussion
The prevalence of visual impairment after cataract extraction defined by BCVA was
approximately 46% lower than the prevalence defined by PVA (29.3% vs 54.41%),
indicating that a high proportion of cataract-operated participants could benefit from
continued ophthalmic follow-up care after cataract extraction. The majority of the
sample were pseudophakic, and therefore the change in the prevalence of visual
impairment was similar when restricting to this group. These results indicate that
pseudophakic cataract-operated participants often require postoperative corrective
lenses to improve their visual acuity. However, for aphakic, cataract-operated
participants, the prevalence of any visual impairment improved by only 11% after
refraction (PVA 100% visual impairment to 88.9% for BCVA), suggesting that visual
impairment among aphakic participants was not due to other causes than refractive
error. While based on small numbers of aphakic participants, the prevalence of any
visual impairment in pseudophakic participants was significantly lower than in aphakic
participants. The above findings were similar to our previous population-based study of
Latinos with cataract extraction.
20
The crude prevalence of any visual impairment in the worse-seeing eye after cataract
extraction based on presenting visual acuity for Chinese Americans was 54.4% (95%CI:
49.8, 59.0) compared to 60.5% (95%CI: 54.6, 66.5) for Latinos. Using the age-
adjusted
27
prevalence of visual impairment for the worse-seeing cataract-extracted eye,
Latinos were 1.3 times as likely to have visual impairment than Chinese American after
cataract extractions (VI for CHES 43.4%; VI for LALES 56.0%). For CHES, the age-
specific prevalence of visual impairment among participants with cataract extractions
was lower in each subsequent age group from 50-59 through of 70-79 year of age. The
13
degree of difference between age groups was smaller for Latinos than Chinese
Americans. The age-specific prevalence of visual impairment among people with history
of cataract extraction was higher in Latinos from 50-79 years but higher among Chinese
American who were 80+ years compared to Latinos.The primary cause of visual
impairment in the worse-seeing cataract-operated eye was macular degeneration for
both the CHES (46.5%) and LALES (12%) populations. Primary open angle glaucoma
(POAG) was the primary cause of visual impairment in 11.1% of in CHES participants
with cataract extraction, whereas 8.1% visual impairment was due to POAG in LALES.
Myopic retinopathy was the primary cause of visual impairment for 15.2% of CHES
cataract extraction participants, however, only 3.8% of LALES cataract extraction
participants with visual impairment. In CHES, the next primary causes of visual
impairment included after-cataract Posterior Capsule Opacity (PCO), PDR and Macular
cyst/hole. In contrast, diabetic retinopathy, corneal opacity, retinal detachment and other
retinal disorders were considered as the next important causes of visual impairment in
LALES.
There were several large population-based studies of visual acuity outcomes after
cataract extraction in Asian populations. To compare the prevalence of visual
impairment among these studies
28-32
, visual impairment for the CHES and LALES
studies were re-defined using the WHO standard (<20/60 using presenting visual
acuity). The WHO definition of visual impairment was used by the Liwan Eye Study,
which is a 5-year population-based eye study of adults living in the Liwan District of
Guangzhou, China
28
.The China nine-province survey
29
and the Beijing Eye Study
30
used <20/63 presenting visual acuity do define visual impairment. Prevalence was
calculated based on all cataract-operated eyes for all studies.
The prevalence of visual impairment for CHES among cataract-operated eyes was
23.6% compared to 29.5% in LALES. However, these numbers were not age-
standardized and CHES participants were older (mean age 75.4 years) compared to
LALES (mean age 72.7 years), suggesting that the difference may be underestimated.
14
The prevalence of visual impairment in CHES was similar to that of the Liwan Eye Study
(22.6% vs. 23.6%) however the mean age of Liwan participants was younger (70.5
years). The prevalence of visual impairment in cataract-extracted eyes was slightly
lower in CHES than Beijing (20.3% vs. 23.6%) with Beijing including slightly younger
participants. The prevalence of visual impairment calculated from the Singapore studies
were similar (26.8% and 25.5%).
31,32
The study of visual impairment among adults from
9 provinces in rural China, revealed a much higher prevalence of visual impairment
(53.5%) than all other studies including CHES. Using the age-adjusted prevalence of
visual impairment for all cataract-extracted eyes, Latinos were 1.7 times as likely to
have visual impairment than Chinese American after cataract extractions (VI for CHES
34.5%; VI for LALES 50.6%).
The study data is derived from The Chinese American Eye Study (CHES), which is a
population-based study of eye disease with a high participation rate and standard
measures of visual acuity. This study is well powered to estimate age-specific and age-
standardized prevalence of visual impairment. The large, population based sample
allows us to better estimate and characterize visual acuity outcomes after cataract
extraction. Another strength was the detailed ophthalmologic examination that allowed
confirmation and characterization (aphakic, phakic, visual impairment presence and
severity, causes of visual impairment) of cataract extraction and visual acuity outcomes.
A study limitation is that cataract extractions were done at other surgical centers and
records on procedures, dates of procedures, and follow-up care were not collected. In
conclusion, this study indicated that a significant portion of cataract-operated
participants had residual visual impairment that required post-operative follow-up care
and corrective lenses, especially among pseudophakic participants.
15
List of tables
Table 1. The Number and Percent of CHES Participants with Visual Impairment (VI) in
the Worse-Seeing Cataract-Operated Eye Overall and by Severity of VI
Visual Impairment [n (%)] *
Status of Cataract
Extraction
None
(<20/40)
Any
(≥20/40)
Mild
(20/40-
20/63)
Moderate
(20/80-
20/160)
Severe
(>160)
Visual impairment defined
by presenting visual acuity
Aphakic (n = 9) 0 (0) 9 (100) 2 (22.2) 2 (22.2) 5 (55.6)
Pseudophakic (n = 445) 207 (46.5) 238 (53.5) 136 (30.7) 70 (15.7) 32 (7.2)
Total (n=454) 207 (45.6) 247 (54.4) 138 (30.4) 72 (15.9) 37 (8.2)
Visual impairment defined
by best-corrected visual
acuity
Aphakic (n = 9) 1 (11.1) 8 (88.9) 2 (22.2) 1 (11.1) 5 (55.6)
Pseudophakic (n = 445) 320 (71.9) 125 (28.1) 80 (18.0) 21 (4.7) 24 (5.4)
Total (n= 454) 321 (70.7) 133 (29.3) 82 (18.1) 22 (4.9) 29 (6.4)
*Visual impairment was defined by presenting visual acuity or best-correct visual acuity of 20/40 or worse
in the worse-seeing cataract-operated eye.
Table 2. The Number and Percent of CHES Participants with Visual Impairment (VI) in
All Cataract-Operated Eyes Overall and by Severity of VI
Visual Impairment [n (%)] *
Status of Cataract
Extraction
None
(<20/40)
Any
(≥20/40)
Mild
(20/40-
20/63)
Moderate
(20/80-
20/160)
Severe
(>160)
Visual impairment defined
by presenting visual acuity
Aphakic (n = 14) 2 (14.3) 12 (85.7) 4 (28.6) 2 (14.3) 6 (42.9)
Pseudophakic (n = 743) 421 (56.7) 322 (43.3) 199 (26.8) 88 (11.8) 35 (4.7)
Total (n=757) 423 (55.9) 334 (44.1) 203 (26.8) 90 (12.0) 41 (5.4)
Visual impairment defined
by best-corrected visual
acuity
Aphakic (n = 14) 4 (28.8) 10 (71.4) 3 (21.4) 1 (7.1) 6 (42.9)
Pseudophakic (n = 743) 573 (77.1) 170 (22.9) 118 (15.9) 25 (3.4) 27 (3.6)
Total (n= 757) 577 (76.2) 180 (23.8) 121 (16.0) 26 (3.4) 33 (4.4)
*Visual impairment was defined by presenting visual acuity or best-correct visual acuity of 20/40 in
cataract-operated eyes.
16
Table 3. Primary Cause of Visual Impairment in Worse-Seeing Cataract-Operated Eye
Visual Impairment in Worse-Seeing Cataract-Operated Eye
[n (%)] *
Primary Cause of Visual
Impairment
Mild
(20/40-20/63)
Moderate
(20/80-20/160)
Severe
(>160)
Total [n (%)]
Myopic retinopathy 7 (7.1) 2 (2.0) 6 (6.1) 15 (15.2)
After-cataract Posterior Capsule
Opacity (PCO)
5 (5.1) 1 (1.0) 0 (0) 6 (6.1)
Macular degeneration 32 (32.3) 9 (9.1) 5 (5.1) 46 (46.5)
Amblyopia 1 (1.0) 0 (0) 0 (0) 1 (1.0)
Macular edema 1 (1.0) 0 (0) 0 (0) 1 (1.0)
Non-proliferative diabetic
retinopathy (NPDR)
1 (1.0) 0 (0) 0 (0) 1 (1.0)
Primary open angle glaucoma
(POAG)
5 (5.1) 3 (3.0) 3 (3.0) 11 (11.1)
Asteroid hyalosis 1 (1.0) 0 (0) 0 (0) 1 (1.0)
Macular cyst/hole/pseudo 2 (2.0) 0 (0) 1 (1.0) 3 (3.0)
Optic nerve atrophy 0 (0) 0 (0) 2 (2.0) 2 (2.0)
PDR 0 (0) 0 (0) 4 (4.0) 4 (4.0)
Cornial scar & opacity 1 (1.0) 0 (0) 0 (0) 1 (1.0)
Other retinal disorders 1 (1.0) 0 (0) 0 (0) 1 (1.0)
Epiretinal membrane 2 (2.0) 0 (0) 0 (0) 2 (2.02)
Cornial edema transplant 0 (0) 0 (0) 1 (1.01) 1 (1.01)
Primary angle closure glaucoma
(PACG)
1 (1.0) 0 (0) 0 (0) 1 (1.0)
retinal detachment 1 (1.0) 1 (1.0) 0 (0) 2 (2.0)
Total 61 (61.6) 16 (16.2) 22 (22.2) 99 (100)
*Severity of visual impairment was defined by best-corrected visual acuity in worse-seeing eye.
17
Table 4. Primary Cause of Visual Impairment in All Cataract-Operated Eyes
Visual Impairment in all Cataract-Operated Eyes
[n (%)] *
Primary Cause of Visual
Impairment
Mild
(20/40-20/63)
Moderate
(20/80-20/160)
Severe
(>160)
Total [n (%)]
Myopic retinopathy 10 (7.6) 2 (1.5) 7 (5.3) 19 (14.5)
After-cataract Posterior Capsule
Opacity (PCO)
7 (5.3) 1 (0.8) 0 (0) 8 (6.1)
Macular degeneration 49 (37.4) 11 (8.4) 7 (5.3) 67 (51.2)
Amblyopia 1 (0.8) 0 (0) 0 (0) 1 (0.8)
Macular edema 1 (0.8) 0 (0) 0 (0) 1 (0.8)
Non-proliferative diabetic
retinopathy (NPDR)
1 (0.8) 0 (0) 0 (0) 1 (0.8)
Primary open angle glaucoma
(POAG)
8 (6.1) 3 (2.3) 3 (2.3) 14 (10.7)
Asteroid hyalosis 2 (1.5) 0 (0) 0 (0) 2 (1.5)
Macular cyst/hole/pseudo 2 (1.5) 0 (0) 1 (0.8) 3 (2.3)
Optic nerve atrophy 0 (0) 0 (0) 2 (1.5) 2 (1.5)
Proliferative diabetic retinopathy
(PDR)
0 (0) 0 (0) 4 (3.1) 4 (3.1)
Cornial scar& opacity 1 (0.8) 0 (0) 0 (0) 1 (0.8)
Other retinal disorders 1 (0.8) 0 (0) 0 (0) 1 (0.8)
Epiretinal membrance 3 (2.3) 0 (0) 0 (0) 3 (2.3)
Cornial edema transplant 0 (0) 0 (0) 1 (0.8) 1 (0.8)
Primary angle closure glaucoma
(PACG)
1 (0.8) 0 (0) 0 (0) 1 (0.8)
retinal detachment 1 (0.8) 1 (0.8) 0 (0) 2 (1.5)
Total 88 (67.2) 18 (13.7) 25 (19.1) 131 (100)
*Severity of visual impairment was defined by best-corrected visual acuity.
18
Table 5. Age-specific, crude, and age-standardized prevalence of visual impairment
a
based on presenting visual acuity in the worse seeing, cataract operated eye among
participants with a history of cataract surgery from the Chinese American Eye Study
(CHES) and the Los Angeles Latino Eye Study (LALES)
Chinese American (CHES) Latinos (LALES)
Age Prevalence (95% CI) Prevalence (95% CI)
50-59 35.0 (20.2, 49.8) 50.0 (28.1, 71.9)
60-69 40.0 (29.9, 50.1) 59.4 (47.8, 70.1)
70-79 51.0 (42.9, 59.1) 59.0 (49.4, 68.6)
80+ 68.7 (61.9, 75.5) 60.7 (48.4, 73.0)
total 54.4 (49.8, 59.0) 59.6 (53.7, 65.5)
Adjusted Rate
b
43.4 (38.8, 48.0) 56.0 (49.8, 62.2)
a
Visual impairment was defined by presenting visual acuity of 20/40 or worse in the worse-seeing
cataract-operated eye.
b
Standard population was based on the Annual State Resident Population Estimates for 5 Racial Groups
2010 Census from the U.S. Census Bureau.
Table 6. Prevalence of visual impairment among all cataract-operated eyes based on
presenting visual acuity and among CHES participants compared to LALES and other
population-based studies of visual impairment among adults of Chinese Ancestry in
Asia
WHO definition of VI (<20/60)
Study Range of age (Mean) Visual Impairment (%)
a
CHES 50+ (75.4) 23.6
LALES 50+ (72.7) 29.5
LIWAN
b
50+ (70.5) 22.6
BEIJING
b
45+ (71.3) 20.3
SINGAPORE(Malay)
40 – 80 (. ) 26.8
SINGAPORE (Indian)
40+ (.) 25.5
Rural China (9 province)
b
50+ (.) 53.5
The U.S definition of VI (<20/40)
c
CHES 50+ (75.4) 34.5
LALES 50+ (72.7) 50.6
a
Visual impairment was defined by presenting visual acuity of 20/60 or worse in all cataract-operated eye.
b
Prevalence based on crude, non-standardized estimates reported in original publication
b
Defined visual impairment using 20/63 instead of 20/60
c
Age standardized to the Annual State Resident Population Estimates for 5 Racial Groups 2010 Census
from the U.S. Census Bureau
19
References
1.Pascolini D, Mariotti SP. Global estimates of visual impairment: 2010. Br J
Ophthalmol. 2012;96:614–618.
2. Rao GN, Khanna R, Payal A. The global burden of cataract. Curr Opin Ophthalmol.
2011;22:4–9.
3. Congdon N, O’Colmain B, Klaver CC, et al. Causes and prevalence of visual
impairment among adults in the United States. Arch Ophthalmol. 2004;122:477–485.
4. The Rise of Asian Americans. 2012. Available at:
http://www.pewsocialtrends.org/files/2012/06/SDT-The-Rise-of-Asian-Americans-Full-
Report.pdf. Accessed June 25, 2014.
5. The U.S. Census Bureau. The Asian Population: 2010.Available at:
http://www.census.gov/prod/cen2010/briefs/c2010br-11.pdf.
6. Munoz B, West SK, Rubin GS, et al. Causes of blindness and visual impairment in a
population of older Americans: The Salisbury Eye Evaluation Study. Arch Ophthalmol.
2000;118:819–825.
7. McGwin G, Khoury R, Cross J, Owsley C. Vision impairment and eye care utilization
among Americans 50 and older. CurrEye Res. 2010;35:451–458.
8. Zhang X, Cotch MF, Ryskulova A, et al. Vision health disparities in the United States
by race/ethnicity, education, and economic status: findings from two nationally
representative surveys. Am J Ophthalmol. 2012;154(suppl 6): S53–S62.e51.
9. Congdon N, Vingerling JR, Klein BE, et al. Prevalence of cataract and
pseudophakia/aphakia among adults in the United States. Arch Ophthalmol.
2004;122:487–494.
10. Schein OD, Cassard SD, Tielsch JM, Gower EW. Cataract surgery among Medicare
beneficiaries. Ophthalmic Epidemiol. 2012;19:257–264.
11. Cotter SA, Varma R, Ying-Lai M, Azen SP, Klein R. Causes of low vision and
blindness in adult Latinos: the Los Angeles latino Eye Study. Ophthalmology.
2006;113:1574–1582.
12. Varma R, Torres M; Los Angeles Latino Eye Study Group. Prevalence of lens
opacities in Latinos: the Los Angeles Latino Eye Study. Ophthalmology.
2004;111:1449–1456.
20
13. Varma R, Richter GM, Torres M, Foong AW, Choudhury F, Azen SP. Four-year
incidence and progression of lens opacities: the Los Angeles Latino Eye Study. Am J
Ophthalmol. 2010;149:728–734 e721–722.
14. Richter GM, Chung J, Azen SP, Varma R. Prevalence of visually significant cataract
and factors associated with unmet need for cataract surgery: Los Angeles Latino Eye
Study. Ophthalmology. 2009;116:2327–2335.
15. Richter GM, Torres M, Choudhury F, Azen SP, Varma R. Risk factors for cortical,
nuclear, posterior subcapsular, and mixed lens opacities: the Los Angeles Latino Eye
Study. Ophthalmology. 2012;119:547–554.
16. Richter GM, Choudhury F, Torres M, Azen SP, Varma R. Risk factors for incident
cortical, nuclear, posterior subcapsular, and mixed lens opacities: the Los Angeles
Latino Eye Study. Ophthalmology. 2012;119:2040–2047.
17. Wilson CJ, Rust G, Levine R, Alema-Mensah E. Disparities in vision impairment
among adults in the United States. Ethn Dis. 2008;18(2 Suppl 2):242–246.
18. Zambelli-Weiner A, Crews JE, Friedman DS. Disparities in adult vision health in the
United States. Am J Ophthalmol. 2012;154(Suppl 6): S23–S30.e21.
19. Barañ ano AE, Wu J, Mazhar K, et al, Los Angeles Latino Eye Study Group. Visual
acuity outcomes after cataract extraction in adult Latinos: the Los Angeles Latino Eye
Study. Ophthalmology 2008;115:815–21.
20. Varma R, Paz SH, Azen SP, et al, Los Angeles Latino Eye Study Group. The Los
Angeles Latino Eye Study: design, methods, and baseline data. Ophthalmology
2004;111:1121–31.
21. Rohit Varma, Chunyi Hsu, Dandan Wang, Mina Torres, Stanley P. Azen & the
Chinese American Eye Study Group (2013) The Chinese American Eye Study: Design
and Methods, Ophthalmic Epidemiology, 20:6, 335-347, DOI:
10.3109/09286586.2013.823505
22. Ferris FL III, Kassoff A, Bresnick GH, Bailey I. New visual acuity charts for clinical
research. Am J Ophthalmol. 1982;94(1):91-96.
23. Varma R, Kim JS, Burkemper BS, Wen G, Torres M, Hsu C, Choudhury F, Azen
SP, McKean-Cowdin R. Prevalence and causes of visual impairment and blindness in
Chinese American adults: the Chinese American eye study. JAMA Ophthalmol.
2016;134:785–93.
24. Chylack Jr LT, Leske MC, McCarthy D, et al. Lens opacities classification system II
(LOCS II). Arch Ophthalmol 1989;107(7):991–997.
21
25. Leske MC, Connell AM, Wu SY, et al. Prevalence of lens opacities in the Barbados
Eye Study. Arch Ophthalmol 1997; 115(1):105–111.
26. Varma R, Sun J, Torres M, et al. Prevalence of lens opacities in adult Chinese
Americans: the Chinese American Eye Study (CHES). Invest Ophthalmol Vis Sci.
2016;57:6692– 6699. DOI:10.1167/iovs.16-20517
27. The U.S. Census Bureau. standard population was Annual State Resident
Population Estimates for 5 Race Groups. https://www2.census.gov/programs-
surveys/popest/datasets/2010-2016/state/asrh/?C=S;O=A
28. Huang W, Zheng Y, Wang L, Huang S, Liu B, Jin L, et al. Five-year incidence and
postoperative visual outcome of cataract surgery in urban southern China: the Liwan
Eye Study. Invest Ophthalmol Vis Sci. 2012; 53:7936–7942. pmid:23132796
29. Zhao J, Ellwein LB, Cui H, Ge J, Guan H, Lv J, et al. Prevalence and outcomes of
cataract surgery in rural China the China nine-province survey. Ophthalmology.
2010;117(11):2120–8. Epub 2010/07/29. pmid:20663565.
30. Liu B, Xu L, Wang YX, Jonas JB. Prevalence of cataract surgery and postoperative
visual outcome in Greater Beijing: the Beijing Eye Study. Ophthalmology.
2009;116(7):1322–31. Epub 2009/06/09. pmid:19500855.
31. Lavanya R, Wong TY, Aung T, Tan DT, Saw SM, Tay WT, et al. Prevalence of
cataract surgery and post-surgical visual outcomes in an urban Asian population: the
Singapore Malay Eye Study. The British journal of ophthalmology. 2009;93(3):299–304.
Epub 2008/10/18. pmid:18927226.
32. Gupta, P., Zheng, Y., Ting, T.W., Lamoureux, E.L., Cheng, C.Y. and Wong, T.Y.
(2013) Prevalence of cataract surgery and visual outcomes in Indian immigrants in
Singapore: the Singapore Indian eye study. PLoS ONE, 8, e75584.
Abstract (if available)
Abstract
Purpose: To characterize the prevalence of visual impairment (VI) among adult Chinese Americans with a history of cataract extraction and describe the primary causes of visual impairment among adults with residual VI after cataract extraction. ❧ Design: A population-based study of Chinese Americans age 50+ years. ❧ Participants: 454 participants in the Chinese American Eye Study (CHES) with cataract extraction. ❧ Method: Participants answered an in-home interview and completed a comprehensive ophthalmologic examination. Visual impairment in the cataract-operated eye was defined by 2 criteria: (1) presenting visual acuity where PVA of 20/40 or worse. (2) best-corrected visual acuity where BCVA of 20/40 or worse. The severity of visual impairment was classified by 4 levels: none (<20/40), mild (20/40-20/60), moderate (20/80- 20/160) and severe (>20/160). Causes of visual impairment was determined by ophthalmologists through a chart review. ❧ Primary Outcome Measures: Prevalence of visual acuity among eyes with a history of cataract extraction. ❧ Results: Of the 4582 participants who had a clinical eye examination in CHES, 454 participants had a history of cataract extraction that was verified through the clinical eye examination. Of the 454 participants, 151 (33%) had clinical evidence of a unilateral cataract extraction (9 aphakic and 142 pseudophakic), and 303 (67%) participants had bilateral cataract extractions (5 aphakic and 601 pseudophakic), resulting in a total of 757 cataract-operated eyes. The frequency of VI among cataract extracted eyes was 54.4% based on presenting visual acuity and 29.3% based on best corrected visual acuity
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Liu, Yaorui
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Visual acuity outcomes after cataract extraction in Chinese Americans: the Chinese American Eye Study (CHES)
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Keck School of Medicine
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Applied Biostatistics and Epidemiology
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