It’s a hot, humid October morning at the end of the wet season in Kasi district, in the rural province of Vientiane in the Laos People’s Democratic Republic. The temperature is 30 degrees celsius with 70% humidity and in Kasi, and throughout Vientiane Province, people starting their days in the rice fields and lighting the stoves in the roadside cafes that offer a traditional Lao breakfast of beef noodle pho. Fuelled by their morning pho, the Sight For All research team of optometrists, volunteers, Lao ophthalmologists and ophthalmology fellows and, most importantly, our ex-Laos special forces bus driver are in a minivan packed to the ceiling with microscopes, lenses and vision charts and we’re crawling our way down the main street of Kasi dodging stray dogs and pot holes.
Sight For All, in partnership with the Laos National Ophthalmic Centre, are in Vientiane Province thanks to a grant that Sight For All was awarded by the Lions Clubs International to conduct a survey of childhood refractive error. Refractive error is the technical term for when someone’s eyes don’t focus as well as they should, giving them blurry vision. In Australia, all children are routinely screened for refractive error and, when present, they can be easily treated with glasses and the vast majority of children are cared for by their community optometrists. It’s therefore difficult to imagine that this simple problem could be the largest cause of visual impairment worldwide but in a low-income country like Laos where the economy struggles to keep the roads navigable, and where there are no optometry services available in the community, one can see how there are 670 million people globally who are considered to be visually impaired from a lack of access to correction of their refractive error.
Back in the minivan, our 190cm, broad shouldered driver is staying true to his military training, keeping his aviator sunglasses fixed firmly on the road and every so often flexing his special forces physique as he leans on the horn while over-taking a logging truck, a herd of cows, or a home-built, wooden framed, tractor popular with the locals working the rice fields. We’re on our way to Pha Lao Primary School, 15 kilometres and 45 minutes drive to the north of Kasi where we will be screening their 500 students aged between 6 and 11 for refractive error. The purpose of our survey, and the reason for coming to Laos is because in 2011 we found that only 3.6% of all children had refractive error, and most interestingly, only 0.6% of all children were myopic, or “short-sighted”, a condition where people can see things close to them well, but can’t focus on objects in the distance. This is particularly striking because that data was the lowest ever reported prevalence of myopia from anywhere in the world and we are here 12 years later to find out if things are changing.
The causes of myopia are incompletely understood, but there is general consensus that a key contributor is the interplay of genetic risk factors, including having ancestry from Eastern Asia, as well as environmental risk factors such as doing a lot of “near-work” (think screen time, reading and writing), and spending more years in education. This is precisely why Laos is so interesting. There were multiple waves of immigration to Laos from its northern neighbour China in the 11th, 16th, 19th and 20th centuries and so it is reasonable to expect that the people here will have similar genetic ancestry to those in Southern China. However, in China, up to 80% of all children leaving school are myopic compared to 0.6% in Laos PDR. That’s a gap large enough to drive a truck through. Or, if you’re driving in Laos, probably a truck, a home-built tractor, a heard of cattle and a rattling minivan full of ophthalmologists.
Back at Pha Lao Primary School, the research team are setting up our equipment in a classroom that’s 10 metres long by 4 metres wide. There’s no ceiling, just a corrugated iron roof, no electricity, no glass in the windows and although it’s only 9am the handheld rechargeable plastic fans that we bought at a road-side stall are already whirring away. Children file in one at a time, the youngest year levels first while it’s still relatively cool, and they are asked a few targeted questions about whether there is any family history of eye problems, and whether they have more than an hour of screen time each day. Sitting in a classroom without electricity, in a country where many of these students don’t have electricity at home, one could be forgiven for thinking this is a frivolous question, but China’s booming smart phone industry has established a real foot hold here and 59% of children reply yes, and when it comes time to check how their eyes focus and see whether they have refractive error, it shows.
The children from Pha Lao Primary and across Vientiane province are found to have a significant decrease in the mean spherical equivalent refraction (SE), which is roughly equivalent to an “average glasses prescription”, compared to 2011. The average SE of the children we saw was +0.38, compared to +0.60 in 2011, which means they are, on average, more myopic than 2011. In addition, these children are 6 times more likely to be myopic than in 2011 with 3.8% of the surveyed children now myopic compared to 0.6% in 2011. Similarly, there are only a third as many children who are hypermetropic compared to 2011 (1.0% vs 3.1%). Significantly, the children who answered yes when asked if they have an hour or more of screen time per day are significantly more myopic than those who responded no.
Of the 2373 children seen in Vientiane Province, 18 are visually impaired of whom 6 have moderate visual impairment 1 has severe visual impairment and 1 is legally blind. Sadly, none of these children have been to see an optometrist or ophthalmologist previously, highlighting the need for more primary eye health services in this region. As part of our trip to Vientiane Province, Sight For All had an agreement with Essilor’s One Sight Foundation to provide spectacles to all children who needed them, and we arranged for all children who needed continued ophthalmic follow up or surgery to be seen either by one of the visiting ophthalmologists at the regional centre or at the National Ophthalmic Centre in Vientiane. Moving forward however, as Laos continues to develop and Lao children perform more and more near work we can expect the amount of myopia to increase. In order to address this impending surge, Sight For All is taking steps now to train paediatric ophthalmologists in Laos as well as further developing primary eye health services outside of Vientiane so that children can be screened for refractive error and vision loss. We believe a comprehensive screening service for primary school aged children is within our grasp and we’re committed to working towards this goal.
Dr Thomas Rogerson
