Rapid Assessment Of Avoidable Blindness Research Articles

What is the appropriate age range of individuals to be included in a survey to estimate the prevalence of trachomatous trichiasis?

IntroductionA survey to determine the prevalence of trachomatous trichiasis (TT) requires a large sample size and the recommended participant age is ≥15 years. This study sought to establish the appropriate...

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

BackgroundA 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...

Rapid assessment of avoidable blindness in the Occupied Palestinian Territories.

BackgroundThere are no recent data on the prevalence and causes of blindness in the Occupied Palestinian Territories. The aim of our study was to estimate the prevalence and causes of blindness and visual impairment in the population aged 50 years and above in the Occupied Palestinian Territories using the Rapid Assessment of Avoidable Blindness (RAAB) survey method.Methods and FindingsClusters of 40 people who were 50 years and above were selected with probability proportionate to size using a multistage cluster random sampling method. Participants received a comprehensive ophthalmic examination in their homes, including visual acuity testing by one of three experienced ophthalmologists. The principal cause for visual loss was determined by an experienced ophthalmologist using portable diagnostic instruments. Information about previous cataract surgery, satisfaction with surgery and barriers to cataract surgery were collected. The prevalence of self-reported diabetes was also determined. The prevalence of bilateral blindness (VA<3/60 in the better eye with available correction) was 3.4% (95% CI: 2.7–4.0), 2.0% (95% CI: 1.4–2.5) for severe visual impairment (VA≥3/60 and <6/60), and 7.4% (95% CI: 6.4–8.3) for visual impairment (VA≥6/60 and <6/18). Avoidable causes (i.e. cataract, refractive error, aphakia, surgical complications, corneal scarring and phthysis) accounted for 80.0% of bilateral blindness, severe visual impairment (70.7%) and visual impairment (86.2%). Cataract was the main cause of blindness (55.0%). The prevalence of blindness was higher in Gaza (4.9%, 95% CI: 3.7–6.1%) than in the West Bank (2.5%, 95% CI: 1.9–3.1%) and among women (4.3%,95% CI: 3.3–5.2%) compared to men (2.2%,95%CI:1.5–2.9%). Among people who had undergone cataract surgery in the past, only 54.5% of eyes obtained a good outcome (VA≥6/18), 23.2% had a borderline outcome (VA<6/18 and ≥6/60) and 22.3% had a poor outcome (VA<6/60) with available correction. The prevalence of self-reported diabetes mellitus in ≥50 year age group was 26.4% (95% CI: 24.9–27.9).ConclusionsThe prevalence of blindness suggests that significant numbers of people in the Occupied Palestinian Territories exist who do not access eye care - predominantly women and those residing in Gaza. Programmes need to focus on maximizing the use of current services by these excluded groups.

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.

Estimating numbers of blind children for planning services: findings in Kilimanjaro, Tanzania

Aim:Childhood blindness is included in the VISION 2020 initiative. However, childhood blindness is rare, so there is limited population-based evidence to assist with the planning of services. We carried out...

Rapid Assessment of Avoidable Blindness in India

BackgroundRapid assessment of avoidable blindness provides valid estimates in a short period of time to assess the magnitude and causes of avoidable blindness. The study determined magnitude and causes of avoidable blindness in India in 2007 among the 50+ population.Methods and FindingsSixteen randomly selected districts where blindness surveys were undertaken 7 to 10 years earlier were identified for a follow up survey. Stratified cluster sampling was used and 25 clusters (20 rural and 5 urban) were randomly picked in each district.. After a random start, 100 individuals aged 50+ were enumerated and examined sequentially in each cluster. All those with presenting vision <6/18 were dilated and examined by an ophthalmologist. 42722 individuals aged > = 50 years were enumerated, and 94.7% examined. Based on presenting vision,, 4.4% (95% Confidence Interval[CI]: 4.1,4.8) were severely visually impaired (vision<6/60 to 3/60 in the better eye) and 3.6% (95% CI: 3.3,3.9) were blind (vision<3/60 in the better eye). Prevalence of low vision (<6/18 to 6/60 in the better eye) was 16.8% (95% CI: 16.0,17.5). Prevalence of blindness and severe visual impairment (<6/60 in the better eye) was higher among rural residents (8.2%; 95% CI: 7.9,8.6) compared to urban (7.1%; 95% CI: 5.0, 9.2), among females (9.2%; 95% CI: 8.6,9.8) compared to males (6.5%; 95% CI: 6.0,7.1) and people above 70 years (20.6%; 95% CI: 19.1,22.0) compared to people aged 50–54 years (1.3%; 95% CI: 1.1,1.6). Of all blindness, 88.2% was avoidable. of which 81.9% was due to cataract and 7.1% to uncorrected refractive errors/uncorrected aphakia.ConclusionsCataract and refractive errors are major causes of blindness and low vision and control strategies should prioritize them. Most blindness and low vision burden is avoidable.

Rapid Assessment of Avoidable Blindness in Kunming, China

To estimate the magnitude and causes of visual impairment (VI) in people aged > or = 50 years in Kunming using the Rapid Assessment for Avoidable Blindness methodology, and to assess the prevalence of a pupillary defect in participants diagnosed as cataract visually impaired. Population-based cross-sectional survey. We enrolled 2760 residents of Kunming prefecture in southwest China, >50 years of age. Forty-six clusters of 60 people were selected based on population proportional to size. Households from each cluster were selected using compact segment sampling (CSS) or quota sampling when CSS was not feasible. Visual acuity (VA) was assessed using a tumbling E chart. Lens status and cause of VI were determined by ophthalmologists using direct ophthalmoscopy through a dilated pupil where necessary. The pupillary reaction was assessed on undilated pupils when VI was detected. Prevalence of blindness (VA<3/60), severe VI (SVI) (VA<6/60), and VI (VA<6/18) using presenting VA (PVA). The causes of blindness and VI and prevalence of a pupillary defect in the cataract visually impaired were also assessed. Of 2760 enumerated residents, 2588 were examined. The sample prevalence of bilateral blindness was 3.7% (95% confidence interval [CI], 2.8-4.6%). The prevalence of SVI was 3.0% (95% CI, 2.2-3.8%), and of VI was 9.1% (95% CI, 7.5-10.7%). The main cause of blindness was cataract (63.2% of blindness), followed by nontrachomatous corneal scar (14.7%), glaucoma (7.4%), and other posterior segment disease/neurologic disorders (4.2%). A pupillary defect was detected in 16% of those diagnosed with cataract VI. The cataract surgical coverage in the bilaterally blind was 58.9%, and 45% of operated eyes had good outcome with available correction (VA>6/18). The main barrier to cataract surgery was cost. Cataract remains the most important cause of preventable blindness in this poor region of China, and affordable provision of surgery would help to address this problem. Some cases of cataract blindness may not be preventable owing to preexisting comorbidity, as detected by the presence of a pupillary defect.

Rapid assessment of avoidable blindness in Western Rwanda: blindness in a postconflict setting.

BackgroundThe World Health Organization estimates that there were 37 million blind people in 2002 and that the prevalence of blindness was 9% among adults in Africa aged 50 years or older. Recent surveys indicate that this figure may be overestimated, while a survey from southern Sudan suggested that postconflict areas are particularly vulnerable to blindness. The aim of this study was to conduct a Rapid Assessment for Avoidable Blindness to estimate the magnitude and causes of visual impairment in people aged ≥ 50 y in the postconflict area of the Western Province of Rwanda, which includes one-quarter of the population of Rwanda.Methods and FindingsClusters of 50 people aged ≥ 50 y were selected through probability proportionate to size sampling. Households within clusters were selected through compact segment sampling. Visual acuity (VA) was measured with a tumbling “E” chart, and those with VA below 6/18 in either eye were examined by an ophthalmologist. The teams examined 2,206 people (response rate 98.0%). The unadjusted prevalence of bilateral blindness was 1.8% (95% confidence interval [CI] 1.2%–2.4%), 1.3% (0.8%–1.7%) for severe visual impairment, and 5.3% (4.2%–6.4%) for visual impairment. Most bilateral blindness (65%) was due to cataract. Overall, the vast majority of cases of blindness (80.0%), severe visual impairment (67.9%), and visual impairment (87.2%) were avoidable (i.e.. due to cataract, refractive error, aphakia, trachoma, or corneal scar). The cataract surgical coverage was moderate; 47% of people with bilateral cataract blindness (VA < 3/60) had undergone surgery. Of the 29 eyes that had undergone cataract surgery, nine (31%) had a best-corrected poor outcome (i.e., VA < 6/60). Extrapolating these estimates to Rwanda's Western Province, among the people aged 50 years or above 2,565 are expected to be blind, 1,824 to have severe visual impairment, and 8,055 to have visual impairment.ConclusionsThe prevalence of blindness and visual impairment in this postconflict area in the Western Province of Rwanda was far lower than expected. Most of the cases of blindness and visual impairment remain avoidable, however, suggesting that the implementation of an effective eye care service could reduce the prevalence further.

Rapid assessment of avoidable blindness in Negros Island and Antique District, Philippines

Objectives:To conduct rapid assessments of avoidable blindness to estimate the magnitude and causes of blindness in people aged ⩾50 years in Negros Island and Antique district, Philippines.Methods:Clusters of 50 people...

Rapid Assessment of Avoidable Blindness in Nakuru District, Kenya

To estimate the prevalence of avoidable blindness in > or =50-year-olds in Nakuru district, Kenya, and to evaluate the Rapid Assessment for Avoidable Blindness (RAAB), a new methodology to measure the magnitude and causes of blindness. Cross-sectional population-based survey. 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. 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. Visual acuity and principal cause of VA<6/18. 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-> or =6/60) was 5.8% (95% CI, 4.8%-6.8%) in the sample. Definite avoidable causes of blindness (i.e., cataract, refractive error, trachoma, and corneal scarring) were responsible for 69.6% of bilateral blindness and 74.9% of bilateral visual impairment. Cataract was the major cause of blindness (42.0%) and visual impairment (36.0%). The cataract surgical coverage was high, with 78% of those with bilateral cataract who needed surgery having had surgery at VA<3/60. The quality of surgery was of concern because 22% of the 222 eyes that had undergone cataract surgery had VA<6/60 with best correction. The main barriers to surgery were lack of awareness and cost. The RAAB methodology was easy to use, and each team could visit one cluster per day. The prevalence of blindness in > or =50-year-olds in Nakuru district was low, in part due to the high cataract surgical coverage. The RAAB is easy to use and inexpensive and provides information about the magnitude and causes of avoidable blindness that can be used for planning and monitoring eye care services.