Exposure risk analysis of COVID-19 for a ride-sharing motorbike taxi.

A dominant mode of transmission for the respiratory disease COVID-19 is via airborne virus-carrying aerosols. As national lockdowns are lifted and people begin to travel once again, an assessment of the risk associated with different forms of public transportation is required. This paper assesses the risk of transmission in the context of a ride-sharing motorbike taxi-a popular choice of paratransit in South and South-East Asia and Sub-Saharan Africa. Fluid dynamics plays a significant role in understanding the fate of droplets ejected from a susceptible individual during a respiratory event, such as coughing. Numerical simulations are employed here using an Eulerian-Lagrangian approach for particles and the Reynolds-averaged Navier-Stokes method for the background air flow. The driver is assumed to be exhaling virus laden droplets, which are transported toward the passenger by the background flow. A single cough is simulated for particle sizes 1, 10, 50 µ m , with motorbike speeds 1 , 5 , 15 m / s . It has been shown that small and large particles pose different types of risk. Depending on the motorbike speed, large particles may deposit onto the passenger, while smaller particles travel between the riders and may be inhaled by the passenger. To reduce risk of transmission to the passenger, a shield is placed between the riders. The shield not only acts as a barrier to block particles, but also alters the flow field around the riders, pushing particles away from the passenger. The findings of this paper therefore support the addition of a shield potentially making the journey safer.

Rapid assessment of avoidable blindness and needs assessment of cataract surgical services in Satkhira District, Bangladesh.

AIMS: To estimate the magnitude and causes of blindness in people aged > or =50 years in Satkhira district, Bangladesh, and to assess the availability of cataract surgical services. METHODS: 106 clusters of 50 people aged > or =50 years were selected by probability-proportionate to size sampling. Households were selected by compact segment sampling. Eligible participants had their visual acuity measured. Those with visual acuity <6/18 were examined by an ophthalmologist. A needs assessment of surgical services was conducted by interviewing service providers. RESULTS: 4868 people were examined (response rate 91.9%). The prevalence of bilateral blindness was 2.9% (95% confidence interval (CI) 2.4% to 3.5%), that of severe visual impairment was 1.6% (95% CI 1.2% to 2.0%) and that of visual impairment was 8.4% (95% CI 7.5% to 9.3%). 79% of bilateral blindness was due to cataract. The cataract surgical coverage was moderate; 61% of people with bilateral cataract blindness (visual acuity <3/60) had undergone surgery. 20% of the 213 eyes that had undergone cataract surgery had a best-corrected poor outcome (visual acuity <6/60). The cataract surgical rate (CSR) in Satkhira was 547 cataract surgeries per million people per year. CONCLUSIONS: Although the prevalence of blindness and visual impairment was lower than expected, the CSR is inadequate to meet the existing need, and the quality of surgery needs to be improved.

Outcome of cataract surgery at one year in Kenya, the Philippines and Bangladesh.

AIMS: To assess the change in vision following cataract surgery in Kenya, Bangladesh and the Philippines and to identify causes and predictors of poor outcome. METHODS: Cases were identified through surveys, outreach and clinics. They underwent preoperative visual acuity measurement and ophthalmic examination. Cases were re-examined 8-15 months after cataract surgery. Information on age, gender, poverty and literacy was collected at baseline. RESULTS: 452 eyes of 346 people underwent surgery. 124 (27%) eyes had an adverse outcome. In Kenya and the Philippines, the main cause of adverse outcome was refractive error (37% and 49% respectively of all adverse outcomes) then comorbid ocular disease (26% and 27%). In Bangladesh, this was comorbid disease (58%) then surgical complications (21%). There was no significant association between adverse outcome and gender, age, literacy, poverty or preoperative visual acuity. CONCLUSIONS: Adverse outcomes following cataract surgery were frequent in the three countries. Main causes were refractive error and preoperative comorbidities. Many patients are not attaining the outcomes available with modern surgery. Focus should be on correcting refractive error, through operative techniques or postoperative refraction, and on a system for assessing comorbidities and communicating risk to patients. These are only achievable with a commitment to ongoing surgical audit.

Quality of life and visual impairment from cataract in Satkhira district, Bangladesh.

AIMS: To evaluate a vision-related quality of life (QOL) scale (World Health Organization Prevention of Blindness and Deafness Visual Function 20-WHO/PBD VF20) and explore the impact of cataract visual impairment on vision- and health-related QOL in people >or=50 years from Satkhira district, Bangladesh. METHOD: 217 cases visually impaired from cataract and 280 controls with normal vision were interviewed about vision-related QOL (WHO/PBD VF20), generic health-related QOL (EuroQol generic health instrument, EQ-5D) and socio-demographic information. The validity and reliability of the WHO/PBD VF20 were evaluated using standard psychometric tests and criteria. RESULTS: Evidence for validity and reliability of the WHO/PBD VF20 was found. Worsening general functioning, psychosocial and overall eyesight scores were associated with increased visual loss (p for trend<0.001). Cases were more likely to report problems with each EQ-5D descriptive domain and had poorer self-rated health than controls with normal vision (p<0.001). CONCLUSION: Demonstration of the validity and reliability of the WHO/PBD VF20 in this population supports its suitability as a tool for assessing vision-related QOL in low-income settings. The poorer health-related QOL in cases compared with controls suggests an impact of cataract visual impairment on perceived health and well-being, beyond vision-specific experience.

Causes of poor outcome after cataract surgery in Satkhira district, Bangladesh.

AIMS: Recent data have raised concerns about visual outcome following cataract surgery. The aim of this study was to assess the frequency and causes of poor and borderline outcome after cataract surgery in a population-based case series in Satkhira district, Bangladesh. METHODS: A population-based case series was conducted within a population-based cluster survey of people aged over 50 years in Satkhira district where 4868 people underwent visual acuity (VA) screening. Eyes operated for cataract with VA<6/18 were examined in detail by an ophthalmologist, including a full history and dilated fundoscopy, to determine the cause of the visual outcome. RESULTS: Cataract surgery was performed on 213 eyes. Outcome was good (VA>6/18) for 128 eyes (60.1%), borderline (VA<6/18 to 6/60) for 35 eyes (16.4%), and poor (VA<6/60) for 50 eyes (23.5%) with available correction. Borderline and poor outcomes were most commonly due to lack of spectacles (25.8%), poor selection (33.8%), or surgical complications (30.6%). Surgical sequelae, namely posterior capsule opacification, was a less common cause of poor or borderline outcome (9.7%). CONCLUSIONS: Quality of surgical outcomes is of concern in Satkhira district. Increased emphasis on selection of subjects for surgery, provision of spectacles, and monitoring of surgery may improve outcomes.