The myopia generation

Dr Jessica Mountford from the Lions Eye Institute is putting new focus on near-sightedness in children.


Dr Jessica Mountford, the Lions Eye Institute

Rapidly rising in prevalence and associated with a growing socio-economic burden, myopia, or near-sightedness, is now recognised as one of the world’s leading causes of distant visual impairment.   

To help explore the mechanisms involved in the development of early-onset myopia, we are using zebrafish as a model to screen myopia-associated genes, as well as closely following how COVID-19 lockdowns may influence the prevalence of early-onset myopia in school-aged children.  

What is myopia?

Myopia occurs when there has been excessive axial elongation of the eye, resulting in refractive error, as light entering the eye is focused in front of, rather than on the neural retina. Left untreated, high myopia (>-5.00 diopters) can lead to other visual disorders such as retinal detachment, retinal atrophy, myopic maculopathy, glaucoma and cataracts.

Prevalence rates are as high as 97% in some countries (namely within East Asia) and at 17% here in Australia. The World Health Organisation has predicted 3.36 billion people worldwide will become myopic by the year 2030 and this is expected to increase to 50% by the year 2050, with 10% of those developing into high myopia. 

Therefore, it is a condition that is forecast to increasingly burden the healthcare system globally.

Sadly, the fastest rise in prevalence is occurring in school-aged children as young as six years of age, whereby early-onset or juvenile myopia develops.

What causes myopia?

There are several contributing factors attributed to the development of myopia, including both genetics and environmental determinants such as near-work (reading, screen time and schoolwork) and time spent outdoors. 

The rise in early-onset myopia and high myopia prevalence, however, is occurring globally at a rate too rapid to be attributed to genetic variance or environmental factors alone, suggesting a compelling association between complex heterogeneous interactions in eye development and environmental risk factors, yet the fundamental causal mechanisms remain unknown.

Impact of school closures

With global infection rates of SARS-CoV-2 virus still continuing to rise more than 18 months into the pandemic, many parts of the globe are still implementing strict measures to help flatten the curve, including social distancing, mask coverings, border closures, curfews, stay-at-home orders and periods of lockdown.

As a result, many educational institutions such as schools and universities have resorted to online learning. In fact, UNESCO has indicated that the pandemic has created the largest disruption of educational systems in history, affecting nearly 1.6 billion learners in more than 190 countries and all continents. 

Closures of schools and other learning spaces have impacted 94% of the world’s student population, up to 99% in low and lower-middle income countries.

Subsequently, these children have increased their screen time, using devices (such as iPads, tablets and laptops), whilst completing schoolwork at home, consequently increasing their environmental risk of developing early-onset myopia indirectly by limiting the amount of time they spend outdoors in natural light. 

Thus, it is predicted that diagnoses of early-onset myopia will escalate as a result. By investigating this association, protective mechanisms can be implemented into policy reforms in an attempt to lower the environmental risk.  

Genes vs environment

My research at the Lions Eye Institute focuses upon determining the role both genetics and environmental factors have on the development of early-onset myopia. The use of human epidemiological and genetic analyses is essential for identifying genomic regions associated with pathological disease. 

Recent studies have identified novel genetic loci found to be associated with refractive error, however, our understanding of the mechanisms involved in this progress remain unknown. With the use of a high-throughput genetic screening platform in zebrafish (Danio rerio), I aim to determine which genes are involved in the progression of early-onset myopia and how light modulation effects the severity of the disease.

End-game

These studies aim to develop a screening method to link functional myopic phenotypes with known myopia-associated genes, and test how environmental changes may affect this outcome. 

In addition to this, and with the
help of collaborators, locally and abroad, we aim to gather translational information on myopia risk factors such as near work, time spent indoors and outdoors, eye health in a defined group of children living in populations affected by school closures during COVID-19 lockdowns and the prevalence of early-onset myopia.

Given these predicted myopia rates during an increasingly uncertain time, investigating the mechanisms involved in the development of early-onset myopia will be significant and timely in combating an increasingly global socio-economic burden.

Hopefully this will allow for a targeted approach to encourage prevention, government policy change and personalised risk assessments. 

ED: Dr Mountford is the Lions Eye Institute’s Brian King Fellow.