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.

Prevalence and causes of low vision and blindness in a Japanese adult population: the Tajimi Study.

http://www.acrm.org.my/ned/documents/refractiveErrorStudy.pdf

Refractive error and visual impairment in school-age children in Gombak District, Malaysia.

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

A recent estimate by the World Health Organization (WHO) suggests that 161 million persons worldwide have visual impairment, including 37 million blind (best-corrected visual acuity less than 3/60 in the better eye) and 124 million with visual impairment less severe than blindness (best-corrected acuity less than 6/18 to 3/60 in the better eye). This estimate is quoted widely, but because it is based on definitions using best-corrected visual acuity, uncorrected refractive error as a cause of visual impairment is excluded. We reviewed data from population-based surveys of visual impairment worldwide published 1996 onwards that included presenting visual acuity, and estimated the proportion of visual impairment caused by uncorrected refractive error in different sub-regions of the world. We then extrapolated these data to estimate the worldwide burden of visual impairment including that caused by uncorrected refractive error. The total number of persons with visual impairment worldwide, including that due to uncorrected refractive error, was estimated as 259 million, 61% higher than the commonly quoted WHO estimate. This includes 42 million persons with blindness defined as presenting visual acuity less than 3/60 in the better eye, and 217 million persons with less severe visual impairment level defined as presenting visual acuity less than 6/18 to 3/60 in the better eye, 14% and 75% higher, respectively, than the WHO estimates based on best-corrected visual acuity. Sensitivity analysis, taking into account the uncertainty of the proportion of visual impairment caused by refractive error, revealed that the number of persons in the world with visual impairment due to uncorrected refractive error could range from 82 to 117 million. The actual burden of visual impairment worldwide, including that caused by uncorrected refractive error, is substantially higher than the commonly quoted WHO estimate that is based on best-corrected visual acuity. We suggest that the indicative estimate of 259 million persons with visual impairment worldwide, which includes 42 million blind with visual acuity less than 3/60 in the better eye, be used for further planning of the VISION 2020 initiative instead of the often quoted 161 million estimate that includes 37 million blind.

/pdf/what-is-the-global-burden-of-visual-impairment-65ynqutyjc.pdf

What is the global burden of visual impairment

Background: A national eye survey was conducted in 1996 to determine the prevalence of blindness and low vision and their major causes among the Malaysian population of all ages.

Methods: A stratified two stage cluster sampling design was used to randomly select primary and secondary sampling units. Interviews, visual acuity tests, and eye examinations on all individuals in the sampled households were performed. Estimates were weighted by factors adjusting for selection probability, non-response, and sampling coverage.

Results: The overall response rate was 69% (that is, living quarters response rate was 72.8% and household response rate was 95.1%). The age adjusted prevalence of bilateral blindness and low vision was 0.29% (95% CI 0.19 to 0.39%), and 2.44% (95% CI 2.18 to 2.69%) respectively. Females had a higher age adjusted prevalence of low vision compared to males. There was no significant difference in the prevalence of bilateral low vision and blindness among the four ethnic groups, and urban and rural residents. Cataract was the leading cause of blindness (39%) followed by retinal diseases (24%). Uncorrected refractive errors (48%) and cataract (36%) were the major causes of low vision.

Conclusion: Malaysia has blindness and visual impairment rates that are comparable with other countries in the South East Asia region. However, cataract and uncorrected refractive errors, though readily treatable, are still the leading causes of blindness, suggesting the need for an evaluation on accessibility and availability of eye care services and barriers to eye care utilisation in the country.

http://www.acrm.org.my/ned/documents/NationalEyeSurvey_BJO2002.pdf

L. M. Ding

Papers

Prevalence of blindness and low vision in Malaysian population: results from the National Eye Survey 1996