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Introduction
Road traffic crashes are the leading cause of death globally among people aged 5 to 29 years and are predicted to become the seventh most-common cause of all-age mortality by 2030 [1, 2]. Though only 60% of the world’s cars are driven in low- and middle-income countries (LMICs), 90% of traffic crash mortality occurs there [1]. Southeast Asia trails only Africa as the global region with the highest burden of traffic mortality, with 20.7 fatalities per 100,000 population [3]. Drivers aged < 25 years are 15 to 33 times more likely to crash than older drivers [4]. More than 80% of Vietnamese households own at least one motorcycle, which comprise 93% of registered motor vehicles in the country [5]. Southeast Asia is the global region with the highest number of deaths associated with motorcycle use, accounting for 43% of global fatalities, with Vietnam, where motorcycles are involved in over two-thirds of road fatalities, having one of the region’s highest rates of motorcycle-related mortality [3].
Myopic refractive error is the leading cause of distance vision impairment globally and is steadily increasing [6]. Southeast Asia has the highest prevalence of adult myopia (32.9%) of any World Health Organisation (WHO) sub-region [7]. It is estimated that half the world’s population will have myopia by 2050 [8, 9–10]. Uncorrected myopia among young adults in Vietnam, the age group at greatest risk for road traffic death, accounts for 93% of all vision impairment [11, 12]. Although myopia can be safely, effectively and inexpensively treated with spectacles, rates of spectacle ownership among young people who need them are as low as 15–20% in low- and middle-income countries (LMICs) [13, 14].
Good vision is widely perceived to be essential for safe driving, as reflected in motor vehicle licensure laws that require distance vision of a certain standard before receiving a driver’s licence in many countries. However, there is little evidence from existing interventional studies that improving vision enhances traffic safety. Systematic reviews based primarily on studies from high-income countries have largely failed to detect a strong association between central vision and crash risk [15]. However, the situation appears to be different in LMICs. A recent meta-analysis by Piyasena et al. of 13 studies from LMICs revealed a 46% increased risk of road traffic...