Rapid Assessment of Avoidable Blindnessin Iran

Zhale Rajavi, MD, Marzieh Katibeh, MD, Hossain Ziaei, MD, Nassim Fardesmaeilpour, MD,Mojtaba Sehat, PhD, Hamid Ahmadieh, MD, Mohammad Ali Javadi, MD

Purpose: To determine the extent and causes of blindness and visual impairment (VI) in the Varamin district,Iran, in 2009.

Design: Cross-sectional population-based survey.Participants: A total of 3000 noninstitutional inhabitants aged �50 years from February to August 2009.Methods: A standard protocol was used according to the rapid assessment of avoidable blindness (RAAB)

method after an initial 4-day workshop. The clusters were selected through probability-proportionate-to-sizesampling. In each cluster, people were selected by a “cluster compact sampling” method. Visual acuity (VA) wasmeasured using a standard tumbling “E” chart without and with pinhole. Ophthalmologists examinedparticipants with VA �6/18 in either eye. Blindness was verified by the World Health Organization definition(best-corrected VA in the better eye �3/60). Severe VI (SVI) was defined as VA �3/60 and �6/60 and VI wasdefined as VA �6/60 and �6/18 at presentation. The primary cause of VI was defined according to the cause inthe participant’s better eye.

Main Outcome Measures: Prevalence of blindness, SVI, and VI, and their avoidable causes.Results: Among 3000 persons, 2819 (94% response rate), including 1289 men (45.1%) and 1530 women

(54.9%), were examined. The standardized prevalence rates of blindness, SVI, and VI were 1.33 (95% confidenceinterval [CI], 0.91–1.75), 1.39 (95% CI, 0.81–1.97), and 6.91 (95% CI, 5.96–7.86), respectively, and the prevalencerates of avoidable causes (cataract, surgical complication, refractive error, and corneal scar) of blindness, SVI,and VI were 56.1%, 65.0%, and 85.6%, respectively. The principal cause of blindness and SVI was cataract, andthe principal cause of VI was refractive error.

Conclusions: Most blindness, SVI, and VI is due to avoidable causes. Cataract and refractive errors were theleading causes in our context.

Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed

in this article. Ophthalmology 2011;118:1812–1818 © 2011 by the American Academy of Ophthalmology.

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The rate of worldwide blindness at the beginning of the 21stcentury will double by the year 2020 if provision of eye careservices is not improved.1 Therefore, global efforts forplanning and implementing the Vision 2020 program havebeen extended to eliminate avoidable causes of blindness,2

and the method of rapid assessment of avoidable blindness(RAAB) has been designed.3,4

Initial studies in the field of epidemiology of blindnessand low vision were often expensive, time-consuming, andcomplicated. Consequently, they were only carried out in afew countries, with no possibility of being repeated soonafter, and as a result, the ability to assess interventions waslimited. Now, more published data in this field have beenderived from population-based surveys with comparablemethods and definitions.5–10 Midway into the Vision 2020program, population-based studies are still needed to collectbaseline data in areas with insufficient information andaccurate data for monitoring ongoing programs.

In Iran, few studies have been performed during recentyears on the prevalence and causes of blindness and lowvision.11–13 According to these studies, the prevalence ofpresenting blindness in all age groups was 0.39% in an

urban population of the capital city and 0.79% in both rural a

1812

nd urban populations of a deprived province.11,12 In an-ther deprived province, this rate was 1.3% in subjects aged5 years.13 Although these studies have reported valuable

nformation for the first time in this country, the mainutcomes, definitions, and age groups examined have noteen completely compatible with the RAAB method andelated outcomes.

To complete the data and provide more comprehensivendicators, we assessed avoidable causes of blindness andow vision in a chosen district according to the RAABethod. Because similar studies are relatively limited in theiddle East, we hope the results of this survey can be used

or further global evaluations.

aterials and Methods

his cross-sectional study was performed from February to August009 in the Varamin district, in the southeast of Tehran province.he location was chosen because of the middle socioeconomictatus of the inhabitants and its constant population (low immigra-ion rate). A standard protocol was used according to a slightlyodified RAAB method. In the original RAAB method, an oph-

halmologist accompanied each team at the first household visit

nd performed eye examinations to diagnose the cause of visual

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Rajavi et al � Rapid Assessment of Avoidable Blindness in Iran

impairment (VI). In the current study, ophthalmologic examina-tions were not performed simultaneously with visual screening byoptometrists. The study was approved by the ethics Committee ofShahid Beheshti University of Medical Sciences, and informedconsent was obtained from participants.

Sample Selection

Multistage cluster systematic random sampling was performedusing the density of the population in different urban and ruralenumeration areas. By considering the sample frame (district pop-ulation size: 542 832), the estimated prevalence of blindness in theMiddle East region (5.6%),14 a confidence interval (CI) of 95%, aprecision of 10%, an �10% nonresponse rate, and an expecteddesign effect of 1.5 for clusters of 50 persons, the sample size wasestimated at 3000 persons from 60 clusters.

Training

A 4-day workshop, according to the RAAB manual, was heldbefore the initiation of the main study. Participants were mem-bers of 2 research teams, including optometrists, computeroperators, staff of the local health center, drivers, and 2 localophthalmologists.

On the first and second days of the workshop, introductoryinformation, a detailed explanation about the survey area andmethods, and translated RAAB instructions were given to partici-pants. On the third day, both teams examined 40 people aged �50years under the supervision of an expert ophthalmologist (ZH- R)to ensure that an acceptable agreement ratio was achieved(k�0.60). The last day of our workshop included field training inthe survey area, where each team examined 50 people in their firstcluster under supervision. A field supervisor accompanied theteams at least 1 day per week during the study to confirm thereliability and validity of data.

Definitions

Blindness was defined as visual acuity (VA) of �3/60 in the bettereye with best correction according to the World Health Organiza-tion (WHO) definition and available correction (presenting VA).Severe VI (SVI) was defined as VA �3/60 and �6/60 and VI wasdefined as VA �6/60 and �6/18 in the better eye with availablecorrection. Refractive error, as the cause of visual impairment, wasdefined as VA �6/18 that improved to �6/18 with a pinhole. Weclassified the causes of blindness, SVI, and VI into 4 groups:curable (cataract, refractive error, uncorrected aphakia); prevent-able (surgical complications, trachoma, phthisis, other cornealscars, onchocerciasis); potentially preventable (diabetic retinopa-thy, glaucoma); and other causes (age-related macular degenera-

Table 1. Age and Sex Composition o

Age Group

Male

Survey Area Sample Surv

50–54 yrs 9092 (30.5%) 335 (26.4%) 887255–59 yrs 5396 (18.1%) 266 (20.9%) 558960–64 yrs 4708 (15.8%) 231 (18.2%) 458265–69 yrs 3810 (12.8%) 151 (11.9%) 329970–74 yrs 3403 (11.4%) 124 (9.8%) 281175–79 yrs 1791 (6%) 99 (7.8%) 1634�80 yrs 1595 (5.4%) 64 (5.0%) 1397

All ages 29,795 1289 28,184

ion [AMD], posterior segment lesions, central nervous systemefects). The first 2 categories (preventable and curable) wereesignated as “avoidable causes.”

ampling Framehe clusters were selected through probability-proportionate-to-ize sampling using updated data from the 2005 national census ashe sampling frame. A sketch map was obtained from the localunicipality and the local health authorities, who were asked to

how major landmarks and the approximate distribution of house-olds. Each enumeration area was divided into segments thatncluded �50 people aged �50 years. One segment was randomlyhosen. Households within clusters were selected by a “compactegment sampling” method. All households in the selected seg-ent were included sequentially until 50 people aged �50 years

ad been identified. If the segment did not include 50 people,nother segment was chosen randomly and sampling was contin-ed until 50 people were enrolled.

When an eligible person was absent, the survey teams returnedo the household twice during the survey period. The person wasonsidered as a nonresponder if he/she could not be examined afterrepeated visits.

phthalmic Examinationsurvey record was completed for each eligible person, which

ncluded general demographic information, VA with and withoutsing a pinhole, lens examination, and the principal cause of VI.

Visual acuity was measured by an optometrist at the household,sing a Snellen tumbling “E” letter with optotype size 6/18 (20/60)n one side and 6/60 (20/200) on the other side at 6 and 3 m. Alleasurements were taken in full daylight with available spectacle

orrection. Pinhole vision was also measured when VA was �6/18n either eye, and the participants with no improvement in VAere referred to 1 of the 2 trained local ophthalmologists. We

overed all the accommodation and visit costs. On the conditionhat a patient was disabled or refused to go to the doctor’s office,ur ophthalmologist performed an eye examination at the house-old using a torch, direct ophthalmoscope, and slit lamp in anquipped ambulance. Examination with a dilated pupil was doneith 1 drop of tropicamide 1% in each eye if the cause of VI wasot refractive error, cataract, aphakia, or corneal scar and thenterior chamber depth was normal. Those with signs suggestivef glaucoma and posterior segment disorders were referred to aocal ophthalmologist for measurement of intraocular pressure bypplanation tonometry and funduscopy by ophthalmoscope to de-ermine the correct causes of low vision.

Cataract was diagnosed by observing opacity in red reflex onphthalmoscopy not explained by other reasons. A diagnosis oflaucoma was suspected by a history of the disease or use ofntiglaucoma mediations, high IOP, or cup/disc ratio �0.5.

Survey Area and Sample Population

Female Total

ea Sample Survey Area Sample

%) 563 (36.3%) 17,964 (31%) 898 (31.9%)%) 300 (19.4%) 10,985 (18.9%) 566 (20.1%)%) 260 (16.8%) 9290 (16%) 491 (17.4%)%) 127 (8.2%) 7109 (12.3%) 278 (9.9%)) 153 (9.9%) 6214 (10.7%) 277 (9.8%)) 67 (4.3%) 3425 (5.9%) 166 (5.9%)) 79 (5.1%) 2992 (5.2%) 143 (5.1%)

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Ophthalmology Volume 118, Number 9, September 2011

The primary disorder was recorded as the principal cause ofblindness or VI by the ophthalmologist. If there were multiplecoexisting primary disorders, the one with the easiest method oftreatment was chosen.

Statistical Analysis

The specific software (RAAB test version 4.02 developed in Vi-sual FoxPro v. 7.0) developed for this survey was used for samplesize calculation, cluster selection, data entry, and automatic stan-dardized data analysis. Double entry helped us identify and correctany errors in recording and entering data. Automated data analysiswas performed on the cleaned data set. The prevalence rates ofblindness, SVI, and VI with 95% CIs were obtained by extrapo-lating the age- and sex-specific estimated prevalence to the age andsex structure of the population of the survey area. SPSS version17.0 (SPSS Inc., Chicago, IL) was used for calculating standarderrors after the data had been imported from the main database.

Results

Among 3000 people selected from 60 clusters, 98 (3.3%) were notavailable (absent), 17 (0.6%) were incapable (physically or men-

Table 2. Prevalence of Visual Impairment Categories, with

Blindness (VA < 3/60)Sever(VA

Bilateral Unilateral Eyes Bilateral

50–54 yrs 2 (0.2%) 23 (2.6%) 27 (1.5%) 10 (1.1%)55–59 yrs 8 (1.4%) 17 (3.0%) 33 (2.9%) 2 (0.4%)60–64 yrs 4 (0.8%) 18 (3.7%) 26 (2.6%) 4 (0.8%)65–69 yrs 5 (1.8%) 16 (5.8%) 26 (4.7%) 1 (0.4%)70–74 yrs 3 (1.1%) 32 (11.6%) 38 (6.9%) 11 (4.0%)75–79 yrs 9 (5.4%) 30 (18.1%) 48 (14.5%) 4 (2.4%)�80 yrs 10 (7.0%) 29 (20.3%) 49 (17.1%) 8 (5.6%)All ages 41 (1.5%) 165 (5.9%) 247 (4.4%) 40 (1.4%)

VA � visual acuity.

Table 3. Age- and Sex-Adjusted* Results for Visual Impair

VI Categories

Male Fem

n % 95% CI n %

Blindness: VA �3/60 in the better eye witBilateral blind 386 1.25 �0.59 397 1.41Blind eyes 2142 3.47 �0.98 2355 4.18

Blindness: VA �3/60 in the bBilateral blind 433 1.40 �0.68 456 1.62Blind eyes 2478 4.02 �1.08 2727 4.84

SVI: VA �3/60 and �6/60 in thBilateral SVI 323 1.05 �0.63 496 1.76SVI eyes 1364 2.21 �0.61 1356 2.40

VI: VA �6/60 and �6/18 in theBilateral VI 1801 5.84 �1.27 2279 8.09VI eyes 5413 8.78 �1.37 6094 10.81

CI � confidence interval; SVI � severe visual impairment; VA � visual

*Specific estimated prevalence rates standardized to the age and sex structure

1814

ally unable to communicate), and 66 (2.2%) refused to cooperate.onsequently, 2819 persons (response rate 94%) with a mean (�

tandard deviation) age of 60.8�9.3 years, including 1270 men45.1%) with an average age of 61.7�9.2 years and 1549 women54.9%) with an average age of 60.0�9.3 years, were examined.isual acuity was �6/18 in at least 1 eye in 650 people (23.05%)ho were referred to ophthalmologists for complete eye examina-

ions. The age and sex distribution of the sample population isompared with that of the district area in Table 1. The presentedata show that the examined population was a representativeample of the province in terms of age and sex distribution.

The prevalence rates of blindness, SVI, and VI in people withvailable correction (presenting VA) among different age groupsf the sample population are shown in Table 2. The prevalence ofI categories increased dramatically as participants’ ages in-

reased. For instance, the prevalence of bilateral blindness in-reased from 0.2% in the group aged 50–54 years to 7% in theroup aged �80 years. The same pattern was seen for SVI and VI.

The prevalence rates of all causes of blindness, SVI, and VI arehown in Table 3. The prevalence of bilateral blindness, accordingo the WHO definition, in the population aged �50 years in theample area was 1.33 (95% CI, 0.91–1.75). Moreover, 9.81% ofhe whole population and 16.46% of the inhabitants’ eyes hadome degree of VI or blindness (VA �6/18).

ilable Correction by Age Group, in the Sample Population

ual Impairment0 and <6/60) Visual Impairment (VA >6/60 and <6/18)

ilateral Eyes Bilateral Unilateral Eyes

(1.0%) 24 (1.3%) 21 (2.3%) 39 (4.3%) 76 (4.2%)(1.4%) 12 (1.1%) 23 (4.1%) 30 (5.3%) 68 (6.0%)(2.9%) 21 (2.2%) 31 (6.3%) 48 (9.8%) 98 (10.0%)(2.9%) 9 (1.6%) 17 (6.1%) 33 (11.9%) 62 (11.2%)(4.3%) 27 (4.9%) 40 (14.4%) 44 (15.9%) 112 (20.2%)(5.4%) 14 (4.2%) 30 (18.1%) 21 (12.7%) 64 (19.3%)(9.1%) 23 (8.0%) 32 (22.4%) 23 (16.1%) 69 (24.1%)(2.6%) 130 (2.3%) 194 (6.9%) 238 (8.4%) 549 (9.7%)

Categories in Adults Aged �50 Years in the Survey Area

TotalCumulativeCategories

95% CI n % 95% CI n %

t correction or pinhole (WHO definition)�0.58 783 1.33 �0.42�0.83 4498 3.81 �0.69 — —

eye, with available correction�0.62 890 1.51 �0.46 890 1.51�0.95 5205 4.41 �0.77 5205 4.41

er eye, with available correction�0.78 819 1.39 �0.58 1709 2.90�0.66 2718 2.30 �0.51 7923 6.71

r eye, with available correction�1.33 4080 6.91 �0.95 5789 9.81�1.27 11,507 9.75 �0.98 19,430 16.46

y; VI � visual impairment; WHO � World Health Organization.

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Rajavi et al � Rapid Assessment of Avoidable Blindness in Iran

The foremost cause of blindness and SVI in persons and in alleyes was cataract, and the leading cause of VI was refractive error,although there were some differences between men and women(Table 4). In women compared with men, a higher proportion ofblindness was attributed to cataract (40% vs. 21%). Among 5836

Figure 1. Distribution of avoidable causes of different levels of VI in partuncorrected aphakia. Preventable causes: surgical complications, trachoma,

Table 4. Principal Causes of Blindness (VA �3/60), Severe V(VA �6/60 and �6/18) in P

Blindness

Male Female Total Ma

Refractive errors — 1 (4.5%) 1 (2.4%) 2 (15Cataract, untreated 4 (21.1%) 9 (40.9%) 13 (31.7%) 9 (69Aphakia, uncorrected — — — —Surgical complications 1 (5.3%) — 1 (2.4%) —Trachoma 1 (5.3%) — 1 (2.4%) —Phthisis — 1 (4.5%) 1 (2.4%) —Other corneal scar 3 (15.8%) 3 (13.6%) 6 (14.6%) 1 (7.7Onchocerciasis — — — —Glaucoma — 1 (4.5%) 1 (2.4%) —Diabetic retinopathy 2 (10.5%) 2 (9.1%) 4 (9.8%) —Globe abnormality 1 (5.3%) — 1 (2.4%) —AMD 2 (10.5%) 1 (4.5%) 3 (7.3%) 1 (7.7Other posterior

segment/CNS5 (26.3%) 4 (18.2%) 9 (22%) —

Total 19 (100%) 22 (100%) 41 (100%) 13 (10

AMD � age-related macular degeneration; CNS � central nervous syste

glaucoma and diabetic retinopathy. Other causes: AMD, globe abnormality, oth

xamined eyes, 526 (9.01%) had a history of cataract surgery,ncluding 341 (5.84%) first eyes and 185 (3.16%) second eyes. Ofperated eyes, 247 eyes (46.95%) were those of women and 279yes (53.04%) were those of men. Age-related macular degener-tion and posterior segment disorders were more common in blind

ts aged �50 years, by sex. Curable causes: refractive errors, cataract, andisis, other corneal scar, and onchocerciasis. Potentially preventable causes:

Impairment (VA �3/60 and �6/60), and Visual Impairments with Available Correction

e Visual Impairment Visual Impairment

Female Total Male Female Total

2 (7.4%) 4 (10%) 33 (42.9%) 61 (52.1%) 94 (48.5%)10 (37%) 19 (47.5%) 26 (33.8%) 30 (25.6%) 56 (28.9%)

— — 1 (1.3%) 1 (0.9%) 2 (1%)1 (3.7%) 1 (2.5%) 3 (3.9%) 5 (4.3%) 8 (4.1%)

— — — 1 (0.9%) 1 (0.5%)— — — — —

1 (1.3%) 2 (5%) 2 (2.6%) 3 (2.6%) 5 (2.6%)— — — — —

2 (7.4%) 2 (5%) 1 (1.3%) 2 (1.7%) 3 (1.5%)2 (7.4%) 2 (5%) 3 (3.9%) 3 (2.6%) 6 (3.1%)

— — — — —5 (18.5%) 6 (15%) 3 (3.9%) 8 (6.8%) 11 (5.7%)4 (14.8%) 4 (10%) 5 (6.5%) 3 (2.6%) 8 (4.1%)

27 (100%) 40 (100%) 77 (100%) 117 (100%) 194 (100%)

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Ophthalmology Volume 118, Number 9, September 2011

men. For SVI the reverse pattern was seen: AMD and posteriorsegment disorders were more common in women. The leadingcause of VI in both sexes was refractive error, which was morecommon among women (52% vs. 42%).

Most blindness and SVI and VI causes were avoidable in allage groups. In addition, the rates of some curable causes, includingrefractive error and cataract, were the highest among avoidablecauses of blindness, SVI, and VI (Fig 1).

Discussion

We achieved an acceptable coverage (response rate of 94%)and reported accurate data, because our sample included 5% ofall people aged �50 years in the survey area, who are the mostaffected age group in all countries.23 The standardized prevalenceof bilateral blindness, standardized according to sex and age, was1.33 (95% CI, 0.91–1.75), which is lower than the rates reportedby RAAB studies in other countries (Table 5).5–10 On the otherhand, overall rates of blindness and low vision in our study werehigher than in some developed countries.14–17

The rate of blindness (in people aged �60 years) in the

Table 5. Comparison of Different Rapid Assessme

Country(Sample Size)

Prevalence

Blindness95% CI SVI VI Blindness

China5 (2760) 3.7%(2.8–4.6)

3% 4.1% Cataract (63.2%)Other corneal

scar (14.7%)Glaucoma (7.4%)

Bangladesh6

(4868)1.6%

(2.4–3.5)2.9% 4.8% Cataract (79%)

Posterior segment(13.3%)

India7

(42,722)3.4%

(3.3–3.9)4.4% 16.8% Cataract (81.9%)

RF (7.1%)

Philippines8

NegrosIsland(3649)

2.2%(2–3.2)

1.2% 9.4% Cataract (54%)Posterior segment

(31%)Phthisis and

corneal scar(6%)

Philippines8

AntiqueDistrict(3842)

2.5%(2.4–3.6)

1.1% 6.2% Cataract (63%)Corneal scar and

phthisis (18%)Posterior segment

(16%)Rwanda9

(2206)1.2%

(1.2–2.4)1.3% 5.3% Cataract (65%)

Posterior segment(20%)

Kenya10

(3784)1.5%

(1.5–2.4)2% 5.8% Cataract (42%)

Posterior segment(30.4%)

Iran(Varamin)currentstudy(3000)

1.3%(0.9–1.7)

1.3% 6.9% Cataract (31.7%)Other posterior/

CNS (22%)Other corneal

scar (14.6%)

AMD � age-related macular degeneration; CI � confidence interval; Cimpairment; VI � visual impairment.

previous surveys in Iran showed an immense difference p

1816

etween 2 populations: residents of urban areas of theapital city11 (2.8%, 95% CI, 1.21–4.39) and residents of 2eprived provinces (12.4% and 9.2%),12,13 which could bettributed to their socioeconomic status, different patterns ofye problems, and low access to eye services. In our study,he prevalence of blindness in the same age group was.07%, which is consistent with the results of the Tehranye Study.

In the current study, cataract was revealed as the mostommon cause of blindness and SVI, similar to other stud-es,5–13 followed by posterior segment disorders. Cornealpacity in our setting was not the leading cause, nor was itn the Tehran Eye Study.11 However, it is one of theommon causes of blindness and VI in some regions ofran,12,13 as well as some other countries.5,7,8,18

Even though most studies in Asia,5–8 Africa,9,10 theiddle East region,18,19 Eastern European countries,15

outh America,20 and an American black population21 re-orted cataract as the chief cause of blindness and lowision, some developed countries have declared otherauses of blindness. In North America,14,21 Western Euro-

Avoidable Blindness Surveys Around the World

Main Causes Avoidable Causes

SVI VI Blindness SVI VI

taract (71.4%)her posterior/CNS (7.8%)

Cataract (51.7%)RE (36%)

84.2% 88.3% 94.1%

taract (78.2%)sterior segment(15.4%)

Cataract (41.9%)RE (52.9%)

86.7% 84.6% 95.8%

taract (77.5%)hakia (4.6%)(3.4%)

Cataract (58.1%)RE (32.9%)

88.2% 91.8% 96.4%

taract (75%)(13%)

sterior segment(10%)

RE (54%)Cataract (39%)Posterior segment

(6%)

67% 88% 94%

taract (72%)(13%)

sterior segment(13%)

RE (55%)Cataract (37%)Posterior segment

(6%)

82% 87% 95%

taract (60.7%)sterior segment(32.1%)

Cataract (54.7%)RE (29.9%)

80% 67.4% 87.2%

taract (50%)sterior segment(29.6%)

Cataract (36%)RE (24.1%)

69.6% 75.4% 74.9%

taract (47.5%)D (15%)(10%)

her posterior/CNS (10%)

RE (48.5%)Cataract (28.9%)AMD (5.7%)

56.1% 65% 85.6%

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Rajavi et al � Rapid Assessment of Avoidable Blindness in Iran

have mostly been posterior segment diseases, such as my-opic degeneration, optic neuropathy, AMD, and senile mac-ular degeneration. It seems that although cataract is stillconsidered as the main cause of blindness in developingcountries, posterior segment disorders (e.g., AMD) are morelikely to be responsible for blindness in developed coun-tries. However, limitation of facilities used in a rapid as-sessment should be borne in mind when comparing resultswith other studies, especially in posterior segment disorders.

Our study found that the prevalence of blindness wasalmost equal in men and women; nevertheless, the preva-lence rates of SVI and low vision in women were signifi-cantly higher than in men (1.76�0.78 vs. 1.05�0.63 and8.09�1.33 vs. 5.84�1.27, respectively). A recent compre-hensive meta-analysis of various studies revealed a consis-tent pattern of sexual inequality in eye health22 and reportedthat approximately two thirds of worldwide blindness wasin women, a difference that was significant in most coun-tries and even in some studies in Iran;12,13 however, ourresults did not show such a consistent pattern (the blindnessrate was similar and only SVI was 1.5 times higher inwomen), which is in line with the results of Tehran eyestudy.11

In the current study, 56.1% of blindness, 65% of SVI,and 85.6% of VI were avoidable. Because the accuratediagnosis of glaucoma and diabetic retinopathy require useof special instruments and methods (e.g., Humphrey VisualField Analyzer and Digital Camera System for FundusPhotography), these potentially or partially preventablecauses were considered separately in our rapid assessment.By considering diabetic retinopathy and glaucoma, the ratesof avoidable causes in the above-mentioned groups willincrease to 78%, 75%, and 90%, respectively, rates inaccordance with global and regional records.5–13,23,24

The main burden of blindness and low vision in ourstudy, which cumulatively affected 9.72% and 23.05% ofthe population (bilaterally and unilaterally, respectively), or16.39% of examined eyes (Table 3), cannot be neglected,and in regard to new perspectives of the researchers in thisfield (implying that it is better to consider the presenting VA�20/200 as blindness,25 in contrast with the WHO defini-tion), it should be taken more seriously by health policymakers. By extrapolating the results of the present study toIranian society, it is estimated that �700 000 individualsaged �50 years have some degree of bilateral blindness orlow vision in this country. With the growing population andthe aging of Iranian society in the next decades, we will facea higher prevalence if no appropriate health interventionsare designed and executed. More than 75% of causes areavoidable and can be controlled with simple interventions.

Conclusions

The current study was the first survey carried out in Iranusing the RAAB method. This study demonstrated thatapproximately 10% of the sample population (aged �50years) had different levels of bilateral VI and that 16% ofexamined eyes had VA �6/18. In addition, more than 75%

of cases of blindness and low vision have avoidable causes.

omen were more prone to SVI than men (1.5 times).lthough the prevalence of blindness in Iran is lower than inther countries in the same region, more emphasis on eyeealth is warranted to achieve the same results as in devel-ped countries.

Acknowledgments. The authors thank Dr. A. RamezankhaniVice-Chancellor of Health of Shahid Beheshti Medical Univer-ity) and colleagues, Shahla Ghanbari, and Dr. Abdolazimarkhaneh Yousefi (the chief of Varamin Health Network), whoelped us perform the current study. The authors also thank Dr.raj Jalili, the ophthalmologist who assisted in the eye examina-ions, and Drs. Armen Eskandari and Mehdi Yaseri.

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Originally received: September 5, 2010.Final revision: November 15, 2010.Accepted: January 19, 2011.Available online: May 14, 2011. Manuscript no. 2010-1223.

Ophthalmic Research Center, Labbafinejad Medical Center, Shahid Be-heshti University of Medical Sciences, Tehran, Iran.

The abstract of this article has been accepted as a poster presentation at:The American Academy of Ophthalmology and the Middle East AfricaCouncil of Ophthalmology Joint Meeting, October 16–19, 2010, in Chi-

inancial Disclosure(s):he author(s) have no proprietary or commercial interest in any materialsiscussed in this article.

orrespondence:arzieh Katibeh, MD, Ophthalmic Research Center, Labbafinejad Medicalenter, Boostan 9 St., Pasdaran Ave, 16666, Tehran, Iran. E-mail:

dkatibeh@yahoo.com.