Prevalence and Causes of Blindness and Low Vision Revisited after 5 years of Eye Care in Timor-Leste

Purpose: To estimate the 2010 prevalence and causes of blindness and low vision among Timor-Leste adults aged ≥40 years, and compare these to the results of a survey conducted 5 years previously.

Method: A population-based cross-sectional survey used multistage cluster random sampling proportionate to size to identify 50 clusters of 45 people each. Cause of vision loss was determined for each eye with presenting visual acuity worse than 6/18.

Results: A participation rate of 89.5% (n?=?2014) was achieved. The gender-age-domicile adjusted prevalence was 7.7% (95% confidence interval [CI] 6.5, 8.8) for 6/60, and 3.6% (95% CI 2.7, 4.4) for 3/60 blindness (better eye presenting vision worse than 6/60 and 3/60, respectively) among Timorese aged ≥40 years. Cataract caused most blindness (69.3% at 6/60). The population prevalence of low vision (better eye presenting vision of 6/60 or better, but worse than 6/18) was 13.6% (95%CI 12.1, 15.1), most caused by uncorrected refractive error (57.4%) or cataract (39.5%). The prevalence and causes of blindness were unchanged compared with 5 years earlier, but low vision was less common.

Conclusion: Unusually for a developing country, Timor-Leste has initiated a cycle of evidence-based eye care in which, although with limitations, population data are periodically available for monitoring and planning.     

Prevalence of Blindness and Low Vision in a Rural Population in Northern China: Preliminary Results from a Population-Based Survey

Purpose: To investigate the prevalence of visual impairment in a rural northern Chinese population.

Methods: A cross-sectional, population-based survey was conducted in 2010 in Ci County, Hebei Province in northern China. Residents aged 7 years and older in Lucunying Town, located within Ci County, underwent presenting visual acuity (VA) testing at home; those with presenting VA <20/60 were invited to participate in further examination at the local hospital. Population-weighted prevalences of blindness and low vision were determined according to World Health Organization definitions.

Results: Among the 24,539 residents aged older than 7 years, 20,298 (82.7%) participated in the study, and 20,072 (98.9%) of these had valid VA data. The population-weighted prevalence rates of presenting bilateral blindness and bilateral low vision were 0.3% and 2.4% for the entire population, 0% and 0.5% for residents 7–39 years of age, and 0.8% and 6.4% for residents 40 years and older, respectively. Based on best-corrected VA, the corresponding prevalence rates of bilateral blindness and bilateral low vision were 0.2% and 1.4% for the entire population, 0% and 0.1% for residents 7–39 years, and 0.6% and 4.0% for residents 40 years and older, respectively. Prevalence rates of blindness and low vision were generally higher among women than men. Blindness and low vision increased with age among residents 40 years and older.

Conclusion: Our findings highlight the need for eye healthcare services for visual impairment in rural China.     

Blindness and low vision in The Netherlands from 2000 to 2020—modeling as a tool for focused intervention

Purpose: To estimate the magnitude and causes of blindness and low vision in The Netherlands from 2000 to 2020.

Methods: Recent population-based blindness surveys in established market economies were reviewed. Age and gender specific prevalence and causes of blindness and low vision were extracted and calculated for six population subgroups in The Netherlands. A mathematical model was developed to relate the epidemiologic data with demographic data for each subgroup for each year between 2000 and 2020.

Results: In 2008 an estimated 311,000 people are visually impaired in The Netherlands: 77,000 are blind and 234,000 have low vision. With the current intervention the number may increase by 18% to 367,000 in 2020. Visual impairment is most prevalent among residents of nursing homes and care institutions for the elderly, intellectually disabled persons and people aged 50+ living independently. Of all people with visual impairment 31% is male (97,000) and 69% female (214,000). More than half of all visual impairment (56%; 174,000 persons) is avoidable. A variation of around 20% might be applied to the numbers in these estimates.

Conclusions: The aim of VISION 2020: The Right to Sight to reduce avoidable visual impairment is also relevant for developed countries like The Netherlands. Vision screening and awareness campaigns focusing on the identified risk groups can reduce avoidable blindness considerably. Regular updates of the model will ensure that the prognoses remain valid and relevant. With appropriate demographic data, the model can also be used in other established market economies.     

Perceptions of Eye Health and Eye Health Services among Adults Attending Outreach Eye Care Clinics in Papua New Guinea

Abstract

Purpose: To determine how people attending outreach eye care clinics in Papua New Guinea (PNG) perceive eye health and eye health services.

Methods: An interview-based questionnaire was administrated to a convenience sample of 614 adult participants across four provinces and perceptions of eye health and eye health services were recorded. Presenting and near visual acuity were measured and cause of visual impairment (VI) determined.

Results: In this sample, 113/614 participants (18.4%) presented with distance VI, 16 (2.6%) with distance blindness, and 221 (47.6%) with near VI. Older participants and those with near VI were more likely to indicate that it is hard to have an eye examination due to travel time, lack of transport and transport costs. Female participants and those from underserved areas were more likely to report shame and fear of jealousy from others when asked about their attitudes towards spectacles. Participants reporting that they were willing to pay higher amounts for testing and spectacles/treatment also reported higher education levels, higher household incomes and were more likely to be male. A quarter of participants (25.9%) indicated that they did not like having an eye examination because their reading and writing was poor.

Conclusions: People attending outreach eye care clinics in PNG reported finding it difficult to attend eye health services due to transport difficulties and anticipated high costs. Negative attitudes towards spectacles were also prevalent, and negative perceptions appeared more frequently among older participants and those with less education.     

湖北阳新县2型糖尿病患者盲与低视力状况及原因分析

目的：探讨湖北阳新县2型糖尿病( T2 DM )患者盲与低视力的患病率及原因。
　　方法：纳入8316名常住人口,开展盲与低视力流行病学调查。先将T2 DM患者纳为观察组、将其它受检对象纳为对照组,对比两组盲与低视力患病率及发病原因;随后仅分析观察组数据。
　　结果：观察组盲与低视力出现率明显更高;白内障及视网膜病变出现率明显更高。随年龄增加,观察组盲与低视力出现率明显提升;女性致低视力率明显更高;初中及以上学历者盲与低视力出现率明显更高。上述分析均有统计学意义(P<0.05)。
　　结论：我区T2 DM患者盲与低视力患病率明显高于未合并T2 DM者;T2 DM患者盲与低视力出现与年龄、性别、学历有一定关系。     

The Prevalence of Visual Impairment in Older Adults in Mainland China: A Systematic Review and Meta-Analysis

Purpose: This paper presents estimates of the prevalence of blindness and low vision among older adults over 50 years of age in mainland China. Methods: All primary reports of population-based studies that reported the prevalence or incidence of visual impairment among older populations in mainland China were identified. Twenty-four population-based studies were included in this systematic review. Blindness is defined as visual acuity of less than 3/60, or a corresponding visual-field loss to less than 10 degrees in the better eye with the best possible correction; low vision is defined as visual acuity of less than 6/18, but equal to or better than 3/60 in the better eye with the best possible correction. The pooled prevalence estimates of blindness and low vision were calculated assuming a random-effects model. Relative odds with 95% confidence intervals (95% CIs) were calculated, stratified by methodological and socioeconomic variables. Results: The overall pooled prevalence of blindness was 1.7% (95% CI 1.4-2.1). The results of the meta-regression showed the significance of a predictor variable: geographic region. The blindness rates per 100 older adults in various regions were 1.4 (0.9-2.0) in East China, and 1.4 (1.0-2.0) in Central China and 2.5 (1.9-3.2) in Western China. The overall pooled prevalence of low vision was 4.1% (3.4-5.1) and the independent pooled prevalence rates stratified by geographic region were 3.6% (2.6-5.1) in East China, 3.6% (2.4-5.2) in Central China and 5.2% (3.6-7.4) in Western China. Conclusions: Blindness or low vision affects approximately 5.8% Chinese adults older than 50 years. The prevalence of visual impairment, and especially blindness, vary greatly by the developmental status of geographic region.     

The prevalence and incidence of visual impairment in people of age 20–59 years in industrialized countries: A review

BACKGROUND Reviews on the prevalence of blindness and low vision in persons of age 20 to 59 years are lacking. We have therefore carried out a review based on a Medline search. METHODS The review was confined to epidemiological studies performed in Western Europe, North America and Australia covering the age group 20 to 59 years where there were comparable definitions of blindness and low vision according to the IAPB and WHO classification of blindness and low vision. RESULTS Three surveys, four register studies and two studies based on multiple sources matched our selection criteria. Blindness and low vision are described separately. Blindness Only one study, based on multiple sources, covered the whole age group 20 to 59 years. In this study the overall prevalence of blindness was 0.08%. The prevalence of blindness was 0.04% among those 20–39 years old, whereas in the age group 40–59 years it was 0.1% in two surveys and one study on multiple sources. However, the prevalence was higher, 0.5% among whites and 0.7% among colored, in The Baltimore Eye Study. The definition of blindness was similar in all three studies. Low vision Three studies provided data on the prevalence of low vision in the age group 20–59 years, although the number of cases was very small. In one study the prevalence of a visual acuity =6/24 to 6/48 was 0.07% and in another the prevalence was 0.17% using &lt;6/18 to 0.5/60. No person with low vision was found in the third study. CONCLUSIONS The existing epidemiological data on blindness and low vision among adults aged 20 to 59 years are insufficient. Epidemiological studies based on multiple sources are needed for the study of rare conditions such as blindness and low vision.     

The National Eye Survey of Trinidad and Tobago (NESTT): Rationale,Objectives and Methodology

Purpose: This paper describes the rationale, study design and procedures of the National Eye Survey of Trinidad and Tobago (NESTT). The main objective of this survey is to obtain prevalence estimates of vision impairment and blindness for planning and policy development.

Methods: A population-based, cross-sectional survey was undertaken using random multistage cluster sampling, with probability-proportionate-to-size methods. Eligible participants aged 5 years and older were sampled from the non-institutional population in each of 120 cluster segments. Presenting distance and near visual acuity were screened in their communities. People aged 40 years and older, and selected younger people, were invited for comprehensive clinic assessment. The interview included information on potential risk factors for vision loss, associated costs and quality of life. The examination included measurement of anthropometrics, blood glucose, refraction, ocular biometry, corneal hysteresis, and detailed assessment of the anterior and posterior segments, with photography and optical coherence tomography imaging. Adult participants were invited to donate saliva samples for DNA extraction and storage.

Results: The fieldwork was conducted over 13 months in 2013–2014. A representative sample of 10,651 individuals in 3410 households within 120 cluster segments identified 9913 people who were eligible for recruitment.

Conclusion: The study methodology was robust and adequate to provide the first population-based estimates of the prevalence and causes of visual impairment and blindness in Trinidad and Tobago. Information was also gathered on risk factors, costs and quality of life associated with vision loss, and on normal ocular parameters for the population aged 40 years and older.     

Blindness and Eye Disease in Cambodia

Purpose: To assess the prevalence and etiology of blindness and low vision and to assess the prevalence of common eye diseases in central Cambodia. Methods: In this cross-sectional, population-based study, 6,558 residents of Kandal Province, Cambodia were registered, and 5,803 (88.5%) were interviewed and examined. This house-to-house survey was conducted by a team consisting of a senior ophthalmologist, a Cambodian eye doctor, and eight Cambodian eyecare workers. Results: The prevalence of bilateral blindness (visual acuity <3/60) is 1.1% (95% confidence interval [CI], 0.9–1.4), and an additional 4.4% (95% CI, 3.9–5.0) have low vision (visual acuity < 6/18, ≥3/60 in the better eye). The major causes of bilateral blindness are cataract (67.4%), phthisis (6.1%), uncorrected refractive error (6.1%), corneal scar (5.3%), uncorrected aphakia (3.0%), trachoma corneal scar (3.0%), optic atrophy (3.0%), and others (6.1%). The major causes of low vision are uncorrected refractive error (49.8%) and cataract (42.7%). The prevalence of unilateral blindness is 1.2% (95% CI, 0.9–1.4), often caused by cataract, corneal scar, or phthisis. Trauma due to landmine explosions and war-related injuries was frequently the underlying etiology in subjects with phthisis, corneal scarring, or other pathology.Conclusions: The prevalence of blindness and low vision in Cambodia is relatively high compared to other developing countries. Most of the causes of blindness and low vision are treatable or preventable. Landmines and other war-related injuries are an important cause of ocular injury. These results will assist in developing a national plan for the prevention of blindness in Cambodia.     

Prevalence of Visual Impairment and Uncorrected Refractive Error – Report from a Canadian Urban Population-based Study

Abstract

Purpose: The prevalence of visual impairment due to uncorrected refractive error has not been previously studied in Canada. A population-based study was conducted in Brantford, Ontario.

Methods: The target population included all people 40 years of age and older. Study participants were selected using a randomized sampling strategy based on postal codes. Presenting distance and near visual acuities were measured with habitual spectacle correction, if any, in place. Best corrected visual acuities were determined for all participants who had a presenting distance visual acuity of less than 20/25.

Results: Population weighted prevalence of distance visual impairment (visual acuity <20/40 in the better eye) was 2.7% (n?=?768, 95% confidence interval (CI) 1.8–4.0%) with 71.8% correctable by refraction. Population weighted prevalence of near visual impairment (visual acuity <20/40 with both eyes) was 2.2% (95% CI 1.4–3.6) with 69.1% correctable by refraction. Multivariable adjusted analysis showed that the odds of having distance visual impairment was independently associated with increased age (odds ratio, OR, 3.56, 95% CI 1.22–10.35; ≥65 years compared to those 39–64 years), and time since last eye examination (OR 4.93, 95% CI 1.19–20.32; ≥5 years compared to ≤2 years). The same factors appear to be associated with increased prevalence of near visual impairment but were not statistically significant.

Conclusions: The majority of visual impairment found in Brantford was due to uncorrected refractive error. Factors that increased the prevalence of visual impairment were the same for distance and near visual acuity measurements.     

The Impact of Visual Impairment on Health-related Quality of Life in Rural Africa

Purpose: To assess the impact of visual impairment (VI) on utility values in Sub-Saharan Africa and compare findings with other studies from low- and high-income countries.

Methods: Patients with normal vision and various levels of VI were recruited from a secondary eye clinic in rural Kenya and interviewed using time trade-off (TTO). VI was classified using the World Health Organization definition of (normal vision, visual acuity ≥20/60, VI 20/80–20/200, severe VI 20/240–20/400, and blindness <20/400).

Results: Mean age of the total sample (N?=?303) was 50.3 years (standard deviation, SD, ±18.17 years), and 51.5% of patients were male. Most were small-scale farmers and illiteracy was high at 40%. Mean TTO scores per group were: normal vision 0.93 (SD?±?0.10), VI 0.88 (SD?±?0.14), severe VI 0.86 (SD?±?0.13), blindness 0.73 (SD?±?0.17; p?≤?0.001). Lower TTO scores were independently associated with worse visual acuity (p?≤?0.001), longer duration of disease (p?≤?0.001) and illiteracy (p?=?0.011), but not with cause of VI, age, sex, marital status, socioeconomic status, or systemic comorbidities in multivariate analyses. Overall, TTO scores were considerably higher than those reported from high-income countries at similar levels of VI.

Conclusion: In this rural African population, duration and extent of vision loss, rather than cause, socioeconomic factors and comorbidities affected vision-related quality of life. Our findings underline the importance of providing sight-restoring treatment as timely as possible and the necessity of enhancing rehabilitation efforts for those with non-curable eye diseases.     

Prevalence of Visual Impairment and Blindness in Upper Egypt: A Gender-based Perspective

Purpose: To estimate the prevalence, causes of and risk factors for vision loss in Upper Egypt.

Methods: In this cross-sectional study, four villages in Upper Egypt were randomly selected; within these four villages, households were randomly selected and within the selected households all residents aged ≥40 years were enumerated and enrolled. Door-to-door eye examinations of household members were conducted. Data on relevant demographic and socioeconomic characteristics were collected. The prevalence and causes of vision loss and associated risk factors were assessed. Sex differences in prevalence and determinants were also evaluated.

Results: The prevalence of best eye presenting visual impairment, severe visual impairment, and blindness were 23.9%, 6.4%, and 9.3% respectively. The prevalence of blindness among women significantly exceeded that among men (11.8% vs. 5.4%, respectively, p = 0.021). The prevalence of cataract was 22.9% (higher in women, 26.5% than men 17.2%, p = 0.018). The prevalence of trachomatous trichiasis was 9.7% (higher among women, 12.5%, than men, 5.4%, p = 0.012). The principal causes of blindness were cataract (60%), uncorrected refractive errors (16%) and corneal opacities (12%). Age, sex, family size, illiteracy, unemployment, water source and sanitation methods and living conditions were the major risk factors for vision loss.

Conclusion: The prevalence of visual impairment remains high in Egypt, particularly among women. Risk factors for blindness may differ between men and women. There is a need for qualitative investigations to better understand the causes behind the excess in prevalence of blindness among women.     

Population-Based Assessment of Unilateral Visual Impairment in the South Indian State of Andhra Pradesh: Rapid Assessment of Visual Impairment (RAVI) Project

Purpose: To assess the prevalence and causes of unilateral visual impairment (VI) in the South Indian state of Andhra Pradesh.

Methods: A population-based cross-sectional study was conducted among individuals aged ≥40 years in one urban and two rural locations, using rapid assessment methodology. A 2-stage cluster random sampling method was used to select 7800 individuals from 156 clusters. Distance visual acuity (VA) was assessed using a standard Snellen chart at a distance of 6 m. Eye examinations were conducted using a torchlight and distance direct ophthalmoscopy. Unilateral VI was defined as presenting VA <6/18 in one eye and presenting VA ≥6/18 in the other, and included moderate unilateral VI (<6/18 to 6/60) and unilateral blindness (<6/60).

Results: In total, 7378 individuals (94.6%) were examined. After excluding 918 individuals with VI in the better eye, data were analyzed for the remaining 6460 individuals. Among those included in the analysis, mean age was 50 years (standard deviation 9.6 years), 46.7% were male, 58.9% had no education, and 34.1% were urban residents. The prevalence of unilateral VI was 11.3% (95% confidence interval 10.5–12.1%; n = 730). Uncorrected refractive error was found to be the leading cause (44%; n = 321) of unilateral VI followed by cataract (39.7%; n = 290).

Conclusions: Unilateral VI is common in the South Indian state of Andhra Pradesh. As most of this VI can be addressed with interventions such as cataract surgery and spectacles, service models need to be streamlined to address this need.     

Prevalence of congenital color deficiencies in secondary-school students in Tehran

Purpose. A population-based study was conducted to determine the prevalence of color deficiencies in secondary-school students (ages 12–14) in Tehran. Methods. A total of 2058 students (1136 males, 922 females) were examined with Ishihara pseudoisochromatic color plates. Results. In the study population, 97 cases of defective color vision were detected, including 93 males and 4 females. The affected individuals all had negative histories of previous systemic and ocular disease or chronic use of medications. The visual acuity was 20/20 and the fundus was normal in all affected students. Of the 93 cases of defective color vision in males (8.18%), 56 cases (4.93%) involved deuteranomaly, 13 (1.14%) protanomaly, 13 (1.14%) deuteranopia, and 11 (0.97%) protanopia. The four cases in females (0.43%) involved deuteranomaly in three cases (0.32%) and protanomaly in 1 case (0.11%). Deuteranopia and protanopia were not detected in females. Conclusion. This is the first study to determine the prevalence of congenital color blindness in Iran. The results agree with reports of prevalence of congenital color blindness from Western Europe.     

Rapid Assessment of Avoidable Blindness and Cataract Surgical Services in Kilimanjaro Region,Tanzania

Purpose: To estimate the prevalence and causes of avoidable blindness and visual impairment in persons 50 years of age and older, and to assess the impact of cataract surgical services.

Methods: In this cross-sectional population-based survey, 72 clusters of 50 people 50 years and older were selected by probability proportionate to size sampling. Households within clusters were selected through compact segment sampling. Participants underwent an ophthalmic examination in their homes, including measurement of visual acuity (VA) with a tumbling-E chart and diagnosis of the principal cause of visual impairment. Patients who had been operated on were questioned about details of their cataract surgery.

Results: Three thousand six hundred eligible subjects were selected, of whom 3,436 (95.5%) were examined. The prevalence of bilateral blindness (presenting VA < 3/60) was 2.4% (95% confidence interval [CI], 1.9%–2.9%); prevalence of severe visual impairment was 0.99% (95% CI, 0.98%–0.99%); and prevalence of visual impairment (VA of <?6/18 and ≥ 6/60) was 5.4% (95% CI, 4.6%–6.2%) in the sample. Unoperated cataract accounted for 52.4% of blindness and 70.6% of severe visual impairment. Cataract surgical coverage among people at 3/60 was 68.9%. Overall, 58.6% and 69.6% of the 191 eyes that had undergone cataract surgery had VA greater than or equal to 6/18 with available correction and best correction respectively.

Conclusions: The prevalence of blindness in this population in Kilimanjaro Region was low, reflecting high cataract surgical coverage from an outreach program. Even with high cataract surgical coverage, cataract remains the leading cause of vision loss and an emphasis on quality is needed.     

两种提高脱镜率方法对白内障患者术后视功能影响的对比研究

目的：比较双眼植入多焦点人工晶状体(IOL)和单眼视设计两种方法对白内障术后视功能的影响。

方法：选择2011-01/2012-01于本中心诊断为双眼白内障患者45例90眼,分为多焦点组23例和单眼视组22例,分别植入AcrySof ReSTOR+3D多焦点IOL(SN6AD1,美国Alcon)和单焦点非球面AcrySof IQ(SN60WF)IOL。记录术后3mo时两组患者裸眼远、近、中距离视力,以及对比敏感度、立体视、视功能和生存质量调查问卷,评价患者主观的视觉功能和脱镜率。对计量资料中两组数据进行正态性检验分析,满足正态分布者行t检验,对计数资料行χ²检验。

结果：术后两组双眼裸眼远视力(t=2.001,P=0.052)、中距离视力(t=1.304,P=0.199)、近视力(t=1.642,P=0.108),差异无统计学意义。各空间频率对比敏感度差异无统计学意义(P>0.05)。未矫正远距离立体视差异有统计学意义(P<0.05)。两组术后脱镜率均大于96%。主要视觉干扰中,复视、夜间视物困难和眩光多焦点组比例较高。

结论：双眼植入多焦点IOL与单焦点IOL单眼视设计基本均能获得全程视力,术后脱镜率以及视功能无差异(P>0.05)。     

Changing trends in the prevalence of blindness and visual impairment in a rural district of India: Systematic observations over a decade

Context : Globally, limited data are available on changing trends of blindness from a single region. Aims : To report the changing trends in the prevalence of blindness, visual impairment (VI), and visual outcomes of cataract surgery in a rural district of Andhra Pradesh, India, over period of one decade. Settings and Design : Rural setting; cross-sectional study. Materials and Methods : Using a validated Rapid Assessment of Cataract Surgical Services (RACSS) method, population-based, cross-sectional survey was done in a rural district in the state of Andhra Pradesh, India. Two-stage sampling procedure was used to select participants ≥50 years of age. Further, a comparative analysis was done with participants ≥50 years from the previously concluded Andhra Pradesh Eye Disease Study (APEDS) study, who belonged to the same district. Statistical Analysis : Done using 11 th version of Stata. Results : Using RACSS, 2160/2300 (93.9%) participants were examined as compared with the APEDS dataset (n=521). Age and sex adjusted prevalence of blindness in RACSS and APEDS was 8% (95% CI, 6.9-9.1%) and 11% (95% CI, 8.3-13.7%), while that of VI was 13.6% (95% CI, 12.2-15.1%) and 40.3% (95% CI, 36.1-44.5%), respectively. Cataract was the major cause of blindness in both the studies. There was a significant reduction in blindness following cataract surgery as observed through RACSS (17.3%; 95% CI, 13.5-21.8%) compared with APEDS (34%; 95% CI, 20.9-49.3%). Conclusion : There was a significant reduction in prevalence of blindness and VI in this rural district of India over a decade.     

Recruitment and Testing Protocol in the National Eye Health Survey: A Population-Based Eye Study in Australia

Purpose: To present the recruitment and testing methodology of the National Eye Health Survey (NEHS), a population-based study that aimed to determine the prevalence and causes of vision impairment and blindness in Australia.

Methods: Non-Indigenous Australians aged 50 years and older and Indigenous Australians aged 40 years and older were recruited using a door-to-door approach from 30 randomly selected geographical areas, stratified by remoteness. Participants underwent a vision examination, anterior segment assessment, intraocular pressure testing, perimetry, and fundus photography.

Results: In total, recruiters approached 23,235 residences, and 11,883 residents were successfully contacted (51.1%). Of these, 6760 (56.9%) were deemed eligible and 5764 agreed to participate (positive response rate = 85.3%). Of those who agreed, 4836 residents attended the examination (4836/6760 = 71.5%). This included 1738 Indigenous Australians (41.1% male) aged 40–92 years (mean ± standard deviation = 55.0 ± 10.0 years) and 3098 non-Indigenous Australians (46.4% male), aged 50–98 years (mean ± standard deviation = 66.6 ± 9.7 years).

Conclusions: The NEHS achieved an excellent positive response rate, and the data collected from 4836 Australians will provide the first population-based national estimate of the prevalence of vision impairment and blindness. This data will guide future economic analysis, policy formulation, and eye health service delivery in Australia.     

Prevalence and Causes of Blindness,Low Vision and Status of Cataract in 50 Years and Older Citizen of Qatar—A Community Based Survey

Background: Rapid Assessment for the Avoidable Blindness (RAAB) was conducted in Qatar during 2009. We present the prevalence and determinants of visual disabilities and status of cataract among citizens aged 50 years and older.

Methods: Residents of randomly selected houses and clusters participated in the survey. Opticians noted the presenting and the best corrected vision of participants from 49 clusters. Ophthalmologists examined participants with additional instruments like bio-microscope, digital camera, auto-perimeter and auto-refractor in a mobile van. World Health Organization recommended principal cause of blindness (Visual acuity [VA]?<?3/60 in better eye), Severe visual impairment (SVI) (<6/60), low vision (VA?<?6/18) and unilateral blindness (VA?<?3/60) were designated. Persons with VA?<?6/18 and cataract were interviewed to calculate coverage and barriers for cataract surgeries. Age sex adjusted prevalence of visual disabilities and their 95% Confidence Intervals (CI) were estimated.

Results: We examined 2,433 (97.3%) participants. The age sex adjusted prevalence of bilateral blindness was 1.28% [95% CI 1.22–1.35], SVI (1.67%), low vision (3.66%) and unilateral blindness (3.61%) in 50 years and older population. Female and older age groups were significant risk factors of visual disabilities. Cataract and glaucoma were the main causes of visual disabilities. The coverage of cataract services was 68.2%. Believing that cataract as an aging process (25) and adequate vision in the fellow eye (15) were the reasons for delay in surgery.

Conclusions: To reduce avoidable blindness, un-operated cataract should be addressed. Primary and secondary eye care systems should be strengthened to improve the care of blinding eye diseases in Qatar.     

Causas de la baja visión en los niños: revisión sistemática

ObjectiveTo identify the ocular pathologies that are reported as causes of low vision in children.Material and methodsThe systematic search was carried out in Medline (PubMed), Embase and Lilacs. Observational studies with populations between 0-18 years of age, reporting visual acuity data between 20/60-20/400 and reporting the frequency of ocular pathologies were selected. Studies in which the diagnosis of the condition had not been verified by a professional, or which covered only cases of blindness, uncorrected refractive errors, or amblyopia, were excluded. The methodological quality of the articles was evaluated using the Joanna Briggs Institute instrument for prevalence studies.Results27 studies conducted in Asia (13 publications), Africa (6 studies), Oceania (4 studies), Europe and South America (2 studies each) were included. The most reported causes of low vision were: cataract, with prevalence between 0.8% and 27.2%; albinism with from 1.1% to 47%; nystagmus, with prevalence between 1.3% and 22%; retinal dystrophies between 3.5% and 50%; retinopathy of prematurity (ROP) with prevalence between 1.1% and 65.8%, optic atrophy between 0.2% and 17.6%, and glaucoma from 2.4% to 18.1%.ConclusionsCataract, albinism and nystagmus are the ocular pathologies most mentioned by studies as a cause of low vision in children, as well as retinal diseases such as ROP and optic nerve diseases such as atrophy. However, there are numerous eye conditions that can result in low vision in the pediatric population.