Rapid Assessment of Avoidable Blindness

and to evaluate the Rapid Assessment for Avoidable Blindness (RAAB), a new methodology to measure the magnitude and causes of blindness. Design: Cross-sectional population-based survey. Participants: Seventy-six clusters of 50 people 50 years or older were selected by probability proportionate to size sampling of clusters. Households within clusters were selected through compact segment sampling. Three thousand seven hundred eighty-four eligible subjects were selected, of whom 3503 (92.6%) were examined. Methods: Participants underwent a comprehensive ophthalmic examination in their homes by an ophthalmologist, including measurement of visual acuity (VA) with a tumbling-E chart and the diagnosis of the principal cause of visual impairment. Those who had undergone cataract surgery were questioned about the details of the operation and their satisfaction with surgery. Those who were visually impaired from cataract were asked why they had not gone for surgery. Main Outcome Measures: Visual acuity and principal cause of VA�6/18. Results: The prevalence of bilateral blindness (presenting VA � 3/60) was 2.0 % (95 % confidence interval [CI], 1.5%–2.4%), and prevalence of bilateral visual impairment (VA of �6/18–�6/60) was 5.8 % (95 % CI

Rapid Assessment of Avoidable Blindness in Western Rwanda: Blindness in a Postconflict Setting

A survey of 2,250 people aged 50 y or over in Rwanda, based on clusters of 50 people, found a much lower prevalence of blindness than expected

Avoidable Waste in Ophthalmic Epidemiology: A Review of Blindness Prevalence Surveys in Low and Middle Income Countries 2000–2014

Purpose:- Sources of avoidable waste in ophthalmic epidemiology include duplication of effort, and survey reports remaining unpublished, gaining publication after a long delay, or being incomplete or of poor quality. The aim of this review was to assess these sources of avoidable waste by examining blindness prevalence surveys undertaken in low and middle income countries (LMICs) between 2000 and 2014. Methods:- On December 1 2016 we searched MEDLINE, EMBASE and Web of Science databases for cross-sectional blindness prevalence surveys undertaken in LMICs between 2000–2014. All surveys listed on the Rapid Assessment of Avoidable Blindness (RAAB) Repository website (“the Repository”) were also considered. For each survey we assessed i) availability of scientific publication, survey report, summary results tables and/or datasets; ii) time to publication from year of survey completion and journal attributes; iii) extent of blindness information reported; and iv) rigour when information was available from two sources (i.e. whether it matched). Results:- Of the 279 included surveys (from 68 countries) 186 (67%) used RAAB methodology; 146 (52%) were published in a scientific journal, 57 (20%) were published in a journal and on the Repository, and 76 (27%) were on the Repository only (8% had tables; 19% had no information available beyond registration). Datasets were available for 50 RAABs (18% of included surveys). Time to publication ranged from <1–11 years (mean, standard deviation 2.8±1.8 years). The extent of blindness information reported within studies varied (e.g. presenting and best-corrected, unilateral and bilateral); those with both a published report and Repository tables were most complete. For surveys published and with RAAB tables available, discrepancies were found in reporting of participant numbers (14% of studies) and blindness prevalence (15%). Conclusion:- Strategies are needed to improve the availability, consistency and quality of information reported from blindness prevalence surveys, and hence reduce avoidable waste

Rapid Assessment of Avoidable Blindness: looking back, looking forward.

The Rapid Assessment of Avoidable Blindness, or RAAB, is a relatively simple and low-cost survey methodology to provide data on the prevalence and causes of visual loss. The aim of this article is to reflect on the achievements and challenges of RAAB, and to describe the future developments that are needed to ensure that it remains a relevant and widely used tool. To date, at least 331 RAABs have been undertaken in 79 countries, and these surveys provide an important source of information on visual loss at both the local and global level. A RAAB repository has been developed which includes the site and date of RAABs undertaken, and, where authors have agreed, the core indicators, reports or even raw data from the survey. This dataset has already been used for meta-analyses, and there are further opportunities for its use. Despite these achievements, there are core areas in which RAAB needs to be strengthened so that the full benefits of undertaking the survey can be reaped. Key developments of RAAB are underway, and will include greater use of mobile technologies using a cloud-based platform to enable both digital data collection, real-time survey reviews, reporting and analysis, and a greater emphasis on using the data for planning

Biological processes and links to the physics

Analysis of the temporal and spatial variability of biological processes and identification of the main variables that drive the dynamic regime of marine ecosystems is complex. Correlation between physical variables and long-term changes in ecosystems has routinely been identified, but the specific mechanisms involved remain often unclear. Reasons for this could be various: the ecosystem can be very sensitive to the seasonal timing of the anomalous physical forcing; the ecosystem can be contemporaneously influenced by many physical variables and the ecosystem can generate intrinsic variability on climate time scales. Marine ecosystems are influenced by a variety of physical factors, e.g., light, temperature, transport, turbulence. Temperature has a fundamental forcing function in biology, with direct influences on rate processes of organisms and on the distribution of mobile species that have preferred temperature ranges. Light and transport also affect the physiology and distribution of marine organisms. Small-scale turbulence determines encounter between larval fish and their prey and additionally influences the probability of successful pursuit and ingestion. The impact of physical forcing variations on biological processes is studied through long-term observations, process studies, laboratory experiments, retrospective analysis of existing data sets and modelling. This manuscript reviews the diversity of physical influences on biological processes, marine organisms and ecosystems and their variety of responses to physical forcing with special emphasis on the dynamics of zooplankton and fish stocks

Rapid assessment of avoidable blindness

The planning of eye care programmes requires data on the prevalence and causes of blindness. Unfortunately, programme planning is often hampered by the lack of data, because no surveys have been conducted in the area or the surveys are too old to be relevant. Programme planners are often reluctant to plan surveys, as they are believed to be expensive, time-consuming, and complicated. The Rapid Assessment of Avoidable Blindness (RAAB) has been developed as a simple and rapid survey methodology that can provide data on the prevalence and causes of blindness. So far, RAAB has been successfully undertaken in Kenya,1 Bangladesh,2 the Philippines, Botswana, Rwanda, Mexico, and China (personal communication). RAAB is an updated and modified version of the Rapid Assessment of Cataract Surgical Services (RACSS)

RAAB - Rapid Assessment of Avoidable Blindness

RAAB is a free software package for data entry and analysis of rapid assessment of avoidable blindness surveys

Rapid assessment of avoidable blindness in three counties, Jiangxi Province, China.

BACKGROUND: A survey was undertaken in 2007 to assess the prevalence and causes of blindness and visual impairment in people aged ≥ 50 years in three different counties in Jiangxi, South East China (Gao'an, Xin'gan and Wan'zai). The counties were purposively selected to assess the impact of established non-governmental organisation activities in two counties (Gao'an and Xin'gan) compared with a third county (Wan'zai) without such a programme. METHODS: Clusters of 50 people aged ≥ 50 years were sampled with a probability proportional to the size of the population. Because of differences in expected prevalence and resources available for conducting the surveys, the total sample size varied from 4699 in Gao'an (94.0% response rate) to 3834 in Xin'gan (95.9%) and 2861 (95.4%) in Wan'zai. Households within clusters were selected through random walk sampling. Visual acuity (VA) was measured with a tumbling 'E' chart. Ophthalmologists examined people with VA< 6/18 in either eye. RESULTS: The prevalence of blindness (VA< 3/60 in the better eye with available correction) was similar in Gao'an (1.5%, 95% CI 1.1% to 1.8%), Xin'gan (1.8%, 1.4% to 2.2%) and Wan'zai (1.6%, 1.2% to 2.1%), and the prevalence of visual impairment (VA< 6/18 and ≥ 6/60) was approximately fourfold higher. Cataract was the leading cause of blindness in each of the three counties, while uncorrected refractive error was the dominant cause of visual impairment. The majority of blindness was avoidable in Gao'an (84.3%), Xin'gan (71.0%) and Wan'zai (71.7%). CONCLUSIONS: The prevalence of blindness in the three counties in Jiangxi, China was lower than expected, yet most of the blindness and visual impairment was avoidable, indicating that the prevalence could be reduced further through adequate programme planning and implementation