Who is the most myopic in your family?

Is myopia associated with birth order in an earlier generation, and does education exposure attenuate the effect?

Share options

Author: Daniel Hardiman-McCartney MCOptom, Clinical Adviser
Date: 2 November 2015

Myopia is in the news again. Recently it has been reported that ‘pushy parents were harming their eldest child’s eyesight’. Although one of the more creative headlines, the reports are based on research published in JAMA Ophthalmology.

Professor Jez Guggenhiem, a prominent myopia researcher at Cardiff University, led the study, which you can read in the JAMA ophthalmology. His team looked at data from the UK bio-bank; 89,120 patients aged 40 to 69 years were recruited, with the aim of answering two key questions. Firstly whether myopia was associated with birth order in an earlier generation, and secondly whether education exposure attenuated the effect. For this cohort, computers and smart phone were not in mass use (during the critical period of their ocular development at least) and participants were from a generation prior to the current myopia epidemic.

A higher level of educational attainment is known to be associated with myopia, and this work suggests that some of these patterns have been around for longer than the recent epidemic.

Did the newspapers report the story accurately? Well this time, the newspapers aren't too far from the mark in their reporting of the research. The team at Cardiff that reported this finding are world class researchers; the sample size is large and focuses on supporting the examination of their research question. The researchers have controlled for confounding factors and published clear findings, so it is good, solid research. 

What did the research find? Based on birth order alone, first born children are around 10% more likely to be short sighted and 20% more like to have more severe myopia that their younger siblings. However, when the data was analysed again, with controls for level of educational attainment, this effect was reduced to the point where it was no longer statistically significant. By comparing these two ways of analysing the data the researchers were able to establish that the impact of birth order on myopia risk was related to associated environmental factors (parental behaviour for example) rather than directly to the order of birth. So, although this is not completely new, it confirms what we have speculated about birth order and its relationship with myopia. Birth order is an environmental factor. It is thought that parents push younger children less than first-born children in terms of educational achievement and the reduced educational expectation reduces the risk factors for myopia for those who are not first-born. But this effect is lost if younger siblings pursue / achieve equivalent educational attainments to their older siblings despite the reduced pressure from their parents.

Mike Bowen, director of research at the College of Optometrists, said 'One of the interesting things about the study was that they were looking at the effects of birth order and educational attainment in an older generation than has usually been the focus of research. As global rates of myopia soar, working out how psychosocial environmental factors may have influenced myopia development and progression in the past, as well as now, may help us to understand myopia better. A higher level of educational attainment is known to be associated with myopia, and this work suggests that some of these patterns have been around for longer than the recent epidemic.’

So what should we advise parents in practice? Educational attainment is not only about time spent reading (screens or books), writing, completing homework and classroom performance - physical activity has a vital role in children's development and in academic attainment. For vision, it is now clear that the more of that physical activity that children do outside, the better. When asked about myopia in practice my advice will continue to be: ‘ensure that your children play outside as much as possible and attend regular eye examinations.’ This research doesn’t change that advice, but it adds interesting depth to our understanding of one of environmental factors which effects myopia progression. When next in clinic with a family of myopic children what will you find? 

Daniel Hardiman-McCartney FCOptom
Clinical Adviser, The College of Optometrists

Daniel graduated from Anglia Ruskin University, where he won the Haag Strait prize for best dissertation. Before joining the College, he was Managing Director of an independent practice in Cambridge and a visiting clinician at Anglia Ruskin University. He has also worked as a senior glaucoma optometrist with Addenbrooke’s Hospital in Cambridge, with Newmedica across East Anglia and as a diabetic retinopathy screening optometrist. Daniel was a member of Cambridgeshire LOC from 2007 to 2015 and a member of the College of Optometrists’ Council from 2009 to 2014, representing its Eastern region.  

He is Clinical Adviser to the College of Optometrists for four days each week, dividing the remainder of his time between primary care practice and glaucoma community clinics. Daniel is a passionate advocate of the profession of optometry, committed to supporting all members of the profession and ensuring patient care is always at the heart of optometry. He was awarded Fellowship by Portfolio in December 2018.

Return to blog listings