Findings from a Rapid Assessment of Avoidable Blindness (RAAB) in Southern Malawi

BACKGROUND: Data on prevalence and causes of avoidable blindness in Malawi are not readily available. The purpose of this study was to determine the prevalence and causes of blindness in persons aged 50 and above in southern Malawi to plan eye care services for the community. METHODOLOGY: A population-based survey was conducted in 7 districts in southern Malawi. Villages were selected by probability proportionate to size within each district. Clusters were further subdivided into segments. A predetermined number of segments were selected randomly in each cluster. The survey team moved from house to house in each segment until they had examined 50 people over the age of 50. Examination consisted of visual acuity measurement with tumbling "E" chart and ocular examination by an ophthalmologist. Participants were categorized by visual acuity. Those who were visually impaired (VA<6/18 in the better eye with available correction) were assigned a main cause of visual loss. Further information was sought from anyone who had received cataract surgery. RESULTS: A total number of 3,583 persons aged 50 and above were sampled; among these 3,430 (95.7%) were examined. The prevalence of blindness (presenting visual acuity <3/60 in the better eye) among persons aged 50 and above was 3.3% (95% CI 2.5-4.1). Cataract was the most common cause of blindness contributing to 48.2% of all cases, followed by glaucoma (15.8%) and cornea scarring (12.3%). The cataract surgical coverage in blind persons was 44.6%. CONCLUSION: The prevalence of blindness and visual impairment in persons aged 50 and above was lower than the WHO estimate for Malawi. The majority of the causes were avoidable, with cataract accounting for approximately half of all cases of blindness. The data suggests that expansion of eye care programs to address avoidable causes of blindness is necessary in this area of southern Malawi

Findings from a Rapid Assessment of Avoidable Blindness (RAAB) in Southern Malawi

BACKGROUND: Data on prevalence and causes of avoidable blindness in Malawi are not readily available. The purpose of this study was to determine the prevalence and causes of blindness in persons aged 50 and above in southern Malawi to plan eye care services for the community. METHODOLOGY: A population-based survey was conducted in 7 districts in southern Malawi. Villages were selected by probability proportionate to size within each district. Clusters were further subdivided into segments. A predetermined number of segments were selected randomly in each cluster. The survey team moved from house to house in each segment until they had examined 50 people over the age of 50. Examination consisted of visual acuity measurement with tumbling "E" chart and ocular examination by an ophthalmologist. Participants were categorized by visual acuity. Those who were visually impaired (VA<6/18 in the better eye with available correction) were assigned a main cause of visual loss. Further information was sought from anyone who had received cataract surgery. RESULTS: A total number of 3,583 persons aged 50 and above were sampled; among these 3,430 (95.7%) were examined. The prevalence of blindness (presenting visual acuity <3/60 in the better eye) among persons aged 50 and above was 3.3% (95% CI 2.5-4.1). Cataract was the most common cause of blindness contributing to 48.2% of all cases, followed by glaucoma (15.8%) and cornea scarring (12.3%). The cataract surgical coverage in blind persons was 44.6%. CONCLUSION: The prevalence of blindness and visual impairment in persons aged 50 and above was lower than the WHO estimate for Malawi. The majority of the causes were avoidable, with cataract accounting for approximately half of all cases of blindness. The data suggests that expansion of eye care programs to address avoidable causes of blindness is necessary in this area of southern Malawi

Establishing a method to estimate the effect of antimyopia management options on lifetime cost of myopia

Background Informed decisions on myopia management require an understanding of financial impact. We describe methodology for estimating lifetime myopia costs, with comparison across management options, using exemplars in Australia and China. Methods We demonstrate a process for modelling lifetime costs of traditional myopia management (TMM=full, single-vision correction) and active myopia management (AMM) options with clinically meaningful treatment efficacy. Evidence-based, location-specific and ethnicity-specific progression data determined the likelihood of all possible refractive outcomes. Myopia care costs were collected from published sources and key informants. Refractive and ocular health decisions were based on standard clinical protocols that responded to the speed of progression, level of myopia, and associated risks of pathology and vision impairment. We used the progressions, costs, protocols and risks to estimate and compare lifetime cost of myopia under each scenario and tested the effect of 0%, 3% and 5% annual discounting, where discounting adjusts future costs to 2020 value. Results Low-dose atropine, antimyopia spectacles, antimyopia multifocal soft contact lenses and orthokeratology met our AMM inclusion criteria. Lifetime cost for TMM with 3% discounting was US$7437 (CI US$4953 to US$10 740) in Australia and US$8006 (CI US$3026 to US$13 707) in China. The lowest lifetime cost options with 3% discounting were antimyopia spectacles (US$7280, CI US$5246 to US$9888) in Australia and low-dose atropine (US$4453, CI US$2136 to US$9115) in China. Conclusions Financial investment in AMM during childhood may be balanced or exceeded across a lifetime by reduced refractive progression, simpler lenses, and reduced risk of pathology and vision loss. Our methodology can be applied to estimate cost in comparable scenarios

Potential Lost Productivity Resulting from the Global Burden of Myopia: Systematic Review, Meta-analysis, and Modeling

Purpose: We estimated the potential global economic productivity loss resulting from vision impairment (VI) and blindness as a result of uncorrected myopia and myopic macular degeneration (MMD) in 2015. Clinical Relevance: Understanding the economic burden of VI associated with myopia is critical to addressing myopia as an increasingly prevalent public health problem. Methods: We estimated the number of people with myopia and MMD corresponding to critical visual acuity thresholds. Spectacle correction coverage was analyzed against country-level variables from the year of data collection; variation in spectacle correction was described best by a model based on a human development index, with adjustments for urbanization and age. Spectacle correction and myopia data were combined to estimate the number of people with each level of VI resulting from uncorrected myopia. We then applied disability weights, labor force participation rates, employment rates, and gross domestic product per capita to estimate the potential productivity lost among individuals with each level and type of VI resulting from myopia in 2015 in United States dollars (US$). An estimate of care-associated productivity loss also was included. Results: People with myopia are less likely to have adequate optical correction if they are older and live in a rural area of a less developed country. The global potential productivity loss associated with the burden of VI in 2015 was estimated at US$244 billion (95% confidence interval [CI], US$49 billion–US$697 billion) from uncorrected myopia and US$6 billion (95$2 billion—US$17 billion) from MMD. Our estimates suggest that the Southeast Asia, South Asia, and East Asia Global Burden of Disease regions bear the greatest potential burden as a proportion of their economic activity, whereas East Asia bears the greatest potential burden in absolute terms. Conclusions: Even under conservative assumptions, the potential productivity loss associated with VI and blindness resulting from uncorrected myopia is substantially greater than the cost of correcting myopia

Time scales in nuclear giant resonances

We propose a general approach to characterise fluctuations of measured cross sections of nuclear giant resonances. Simulated cross sections are obtained from a particular, yet representative self-energy which contains all information about fragmentations. Using a wavelet analysis, we demonstrate the extraction of time scales of cascading decays into configurations of different complexity of the resonance. We argue that the spreading widths of collective excitations in nuclei are determined by the number of fragmentations as seen in the power spectrum. An analytic treatment of the wavelet analysis using a Fourier expansion of the cross section confirms this principle. A simple rule for the relative life times of states associated with hierarchies of different complexity is given.Comment: 5 pages, 4 figure

Global Prevalence of Presbyopia and Vision Impairment from Uncorrected Presbyopia: Systematic Review, Meta-analysis, and Modelling

Topic: Presbyopia prevalence and spectacle-correction coverage were estimated by systematic review and meta-analysis of epidemiologic evidence, then modeled to expand to country, region, and global estimates. Clinical Relevance: Understanding presbyopia epidemiologic factors and correction coverage is critical to overcoming the burden of vision impairment (VI) from uncorrected presbyopia. Methods: We performed systematic reviews of presbyopia prevalence and spectacle-correction coverage. Accepted presbyopia prevalence data were gathered into 5-year age groups from 0 to 90 years or older and meta-analyzed within World Health Organization global burden of disease regions. We developed a model based on amplitude of accommodation adjusted for myopia rates to match the regionally meta-analyzed presbyopia prevalence. Presbyopia spectacle-correction coverage was analyzed against country-level variables from the year of data collection; variation in correction coverage was described best by a model based on the Human Development Index, Gini coefficient, and health expenditure, with adjustments for age and urbanization. We used the models to estimate presbyopia prevalence and spectacle-correction coverage in each age group in urban and rural areas of every country in the world, and combined with population data to estimate the number of people with near VI. Results: We estimate there were 1.8 billion people (prevalence, 25%; 95% confidence interval [CI], 1.7–2.0 billion [23%–27%]) globally with presbyopia in 2015, 826 million (95% CI, 686–960 million) of whom had near VI because they had no, or inadequate, vision correction. Global unmet need for presbyopia correction in 2015 is estimated to be 45% (95% CI, 41%–49%). People with presbyopia are more likely to have adequate optical correction if they live in an urban area of a more developed country with higher health expenditure and lower inequality. Conclusions: There is a significant burden of VI from uncorrected presbyopia, with the greatest burden in rural areas of low-resource countries

Potential Lost Productivity Resulting from the Global Burden of Myopia:Systematic Review, Meta-analysis, and Modeling

PURPOSE: We estimated the potential global economic productivity loss resulting from vision impairment (VI) and blindness as a result of uncorrected myopia and myopic macular degeneration (MMD) in 2015.CLINICAL RELEVANCE: Understanding the economic burden of VI associated with myopia is critical to addressing myopia as an increasingly prevalent public health problem.METHODS: We estimated the number of people with myopia and MMD corresponding to critical visual acuity thresholds. Spectacle correction coverage was analyzed against country-level variables from the year of data collection; variation in spectacle correction was described best by a model based on a human development index, with adjustments for urbanization and age. Spectacle correction and myopia data were combined to estimate the number of people with each level of VI resulting from uncorrected myopia. We then applied disability weights, labor force participation rates, employment rates, and gross domestic product per capita to estimate the potential productivity lost among individuals with each level and type of VI resulting from myopia in 2015 in United States dollars (US$). An estimate of care-associated productivity loss also was included.RESULTS: People with myopia are less likely to have adequate optical correction if they are older and live in a rural area of a less developed country. The global potential productivity loss associated with the burden of VI in 2015 was estimated at US$244 billion (95% confidence interval [CI], US$49 billion-US$697 billion) from uncorrected myopia and US$6 billion (95$2 billion-US$17 billion) from MMD. Our estimates suggest that the Southeast Asia, South Asia, and East Asia Global Burden of Disease regions bear the greatest potential burden as a proportion of their economic activity, whereas East Asia bears the greatest potential burden in absolute terms.CONCLUSIONS: Even under conservative assumptions, the potential productivity loss associated with VI and blindness resulting from uncorrected myopia is substantially greater than the cost of correcting myopia.</p