The team studied 1,991 twins all born between 1994 and 1996 in the UK. Opticians provided records to show whether the participants were myopic or not and researchers analysed behavioural, demographic and educational factors between the ages of two and sixteen. Their results, published in the British Journal of Ophthalmology, showed that overall one in four (26%) of the twins was short-sighted and the average age at which children with myopia started wearing glasses to correct the condition was eleven.
The factors found to be most strongly associated with the development of myopia were maternal educational attainment, hours spent playing computer games and being born during the summer.
The authors suggest that hours spent playing computer games may not just be linked to close working but also to less time outdoors: a factor previously found to increase myopia risk.
They also suggest that children born in the summer in the UK start school earlier so start close working at a younger age. This could speed up eye growth which is thought to be responsible for short-sightedness.
Conversely, fertility treatment seemed to afford protection against being short-sighted and was associated with a 25-30 per cent reduced risk. As this has never been found before, the authors want to replicate the results before drawing conclusions but speculate that as children born because of fertility treatment are often smaller, they may have a slight developmental delay which could account for shorter eye length and less myopia.
Professor Chris Hammond, Frost Chair of Ophthalmology and Head of Academic Ophthalmology at King’s, said: