This paper presents estimates of the prevalence of visual impairment and its causes in 2002, based on the best available evidence derived from recent studies. Estimates were determined from data on low vision and blindness as defined in the International statistical classification of diseases, injuries and causes of death, 10th revision. The number of people with visual impairment worldwide in 2002 was in excess of 161 million, of whom about 37 million were blind. The burden of visual impairment is not distributed uniformly throughout the world: the least developed regions carry the largest share. Visual impairment is also unequally distributed across age groups, being largely confined to adults 50 years of age and older. A distribution imbalance is also found with regard to gender throughout the world: females have a significantly higher risk of having visual impairment than males. Notwithstanding the progress in surgical intervention that has been made in many countries over the last few decades, cataract remains the leading cause of visual impairment in all regions of the world, except in the most developed countries. Other major causes of visual impairment are, in order of importance, glaucoma, age-related macular degeneration, diabetic retinopathy and trachoma.

/pdf/global-data-on-visual-impairment-in-the-year-2002-4pvm2ngoxc.pdf

Global data on visual impairment in the year 2002

https://dro.deakin.edu.au/eserv/DU:30146150/islam-causesofblindnessand-2020.pdf

Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study.

PURPOSE For the past 25 years, the WHO Programme for the Prevention of Blindness and Deafness has maintained a Global Data Bank on visual impairment with the purpose of storing the available epidemiological data on blindness and low vision. The Data Bank has now been updated to include studies conducted since the last update in 1994. METHODS An extensive literature search was conducted in international and national scientific and medical journals to identify epidemiological studies that fulfilled basic criteria for inclusion in the Data Bank, namely a clearly stated definition of blindness and low vision, and prevalence rates derived from population-based surveys. Sources such as National Prevention of Blindness Programmes, academic institutions or WHO country or regional reports were also investigated. RESULTS Two-hundred-and-eight population-based studies on visual impairment for 68 countries are reported in detail, providing an up-to-date, comprehensive compilation of the available information on visua...

2002 global update of available data on visual impairment: a compilation of population-based prevalence studies.

In the past decade, several large population based studies have provided new information on the prevalence of visual impairment and the major age related eye diseases in Asia. These include epidemiological studies from India, Taiwan, Mongolia, Singapore, and Japan. In particular, the epidemiology of refractive errors and glaucoma has been well characterised, providing insights not only into the public health implications of these conditions, but also into anatomical changes of the eye with ageing. In contrast, there are few well conducted population based studies on diabetic retinopathy and age related macular degeneration in Asia, two conditions that are likely to be important causes of blindness in the future.

/pdf/the-epidemiology-of-age-related-eye-diseases-in-asia-1ch994npve.pdf

The epidemiology of age related eye diseases in Asia

Background To assess prevalence and causes of blindness and vision impairment in high-income regions and in Central/Eastern Europe in 1990 and 2010. Methods Based on a systematic review of medical literature, prevalence of moderate and severe vision impairment (MSVI; presenting visual acuity Results Age-standardised prevalence of blindness and MSVI decreased from 0.2% to 0.1% (3.314 million to 2.736 million people) and from 1.6% to 1.0% (25.362 million to 22.176 million), respectively. Women were generally more affected than men. Cataract was the most frequent cause of blindness in all subregions in 1990, but macular degeneration and uncorrected refractive error became the most frequent causes of blindness in 2010 in all high-income countries, except for Eastern/Central Europe, where cataract remained the leading cause. Glaucoma and diabetic retinopathy were fourth and fifth most common causes for blindness for all regions at both times. Uncorrected refractive error, followed by cataract, macular degeneration, glaucoma and diabetic retinopathy, was the most common cause for MSVI in 1990 and 2010. Conclusions In highly developed countries, prevalence of blindness and MSVI has been reduced by 50% and 38%, respectively, and the number of blind people and people with MSVI decreased by 17.4% and 12.6%, respectively, even with the increasing number of older people in the population. In high-income countries, macular degeneration has become the most important cause of blindness, but uncorrected refractive errors continue to be the leading cause of MSVI.

https://bjo.bmj.com/content/bjophthalmol/98/5/629.full.pdf

Prevalence and causes of vision loss in high-income countries and in Eastern and Central Europe: 1990-2010

Aim: To determine the age, sex, and cause specific prevalences of blindness and visual impairment in adults 30 years of age and older in Bangladesh.

Methods: A nationally representative sample of 12 782 adults 30 years of age and older was selected based on multistage, cluster random sampling with probability proportional to size procedures. The breakdown of the cluster sites was proportional to the rural/urban distribution of the national population. The examination protocol consisted of an interview, visual acuity (VA) testing, autorefraction, and optic disc examination on all subjects. Corrected VA retesting, cataract grading, and a dilated fundal examination were performed on all visually impaired subjects. The definitions of blindness (<3/60) and low vision (<6/12 to ≥3/60) were based on the presenting visual acuity in the better eye. The World Health Organization/Prevention of Blindness proforma and its classification system for identifying the main cause of low vision and blindness for each examined subject was used.

Results: In total, 11 624 eligible subjects were examined (90.9% response rate) across the 154 cluster sites. A total of 162 people were bilaterally blind (1.53% age standardised prevalence) while a further 1608 subjects (13.8%) had low vision ( 6/12 in the “better eye” in the remaining 9854 subjects (84.8%); however, 748 of these people had low vision in the fellow eye. The main causes of low vision were cataract (74.2%), refractive error (18.7%), and macular degeneration (1.9%). Cataract was the predominant cause (79.6%) of bilateral blindness followed by uncorrected aphakia (6.2%) and macular degeneration (3.1%).

Conclusions: There are an estimated 650 000 blind adults (95% CI 552 175 to 740 736) aged 30 and over in Bangladesh, the large majority of whom are suffering from operable cataract. This survey indicates the need for the development and implementation of a national plan for the delivery of effective eye care services, aimed principally at resolving the large cataract backlog and the inordinate burden of refractive error.

https://bjo.bmj.com/content/bjophthalmol/87/7/820.full.pdf

Prevalence and causes of blindness and visual impairment in Bangladeshi adults: results of the National Blindness and Low Vision Survey of Bangladesh.

Aim: To evaluate the outcome of cataract surgery in the population of Bangladesh. Methods: Data were collected by the National Blindness and Low Vision Prevalence Survey of Bangladesh, a cross sectional, nationally representative sample (12 782 subjects) of the population aged ≥30 years. An interview recorded socioeconomic data. Each subject was tested for logMAR visual acuity (VA) of each eye, autorefracted, and then underwent optic disc examination. Those with Results: 11 624 eligible subjects were examined (90.9% response rate) in the survey. 162 subjects, 77 men and 85 women, had undergone cataract surgery in one or both eyes. 199 (88%) eyes had undergone intracapsular cataract extraction (ICCE), and 22 (10%) extracapsular surgery with intraocular lens (ECCE+IOL); surgical technique(s) in four cases were not identified. Presenting VA for the 226 operated eyes were: 68 eyes (30.1%) were 6/12 or better, 31 (13.7%) Conclusion: This evaluative research study into cataract surgery outcomes in Bangladesh highlights the need for an improvement in quality and increased quantity of surgery with a more balanced distribution of services.

https://bjo.bmj.com/content/bjophthalmol/87/7/813.full.pdf

D M Noorul Huq

Papers

Prevalence and causes of blindness and visual impairment in Bangladeshi adults: results of the National Blindness and Low Vision Survey of Bangladesh.

Outcomes of cataract surgery in Bangladesh: results from a population based nationwide survey.