Sergio Recalde Maestre
Lecturer of the Department of Ophthalmology at the University of Navarra and researcher at the Experimental Ophthalmology Laboratory at the University of Navarra Clinic.
This large study, with more than 340,000 sequenced samples, is a very well conducted analysis of the interaction of genomics and environment in such an important and prevalent disease as myopia. Many studies have been carried out, especially in Asia where childhood myopia shows alarming figures (80%), in which many genes involved in the possible development of this disease have been determined. Similarly, many other studies have shown the importance of changing habits that have led to an imbalance of time spent in outdoor activities and time spent in close-up activities.
This study, through the analysis of the genome-wide association study (GWAS), shows five genetic variants that confer a progressively higher risk of myopia in people who spent more years in education and, therefore, more time in near activities. The paper, which is very well organised and presented, delves in a very simple way into the interaction of the participants' level of education with myopia. In a first phase of participants (88,000) diagnosed with their dioptres, 25 genes were obtained with a certain association depending on whether or not they had a university education. These same genes were analysed in a second phase of patients without dioptres but knowing their years of wearing glasses (252,000) to confirm the association of the gene variants (risk alleles) and obtained a very high significance in five of them (GJD2, RBFOX1, LAMA2, KCNQ5 and LRRC4C). Three of the variants found were novel and the other two had already been observed in the Asian population.
This work is a confirmation of the results that have been observed recently regarding the importance of genetic interaction with the environment in the silent pandemic that is currently myopia. The prevalence of this disease, especially in children, had already been a serious problem in Asia for a few decades, but it is now affecting the world as a whole, and genetic inheritance alone as a risk factor could not account for the dramatic increase in recent years. It was clear that environmental and lifestyle factors (above all in the imbalance between outdoor/close-up work) were also acting in a very powerful way and the fact that they have found, in addition in the Caucasian population, this interaction of several genes that enhance the elongation of the eye due to long periods of study is a great advance.
Having this knowledge must be useful for those people who present these genetic variants to monitor the progression of their myopia more exhaustively during their studies. It also helps them to take breaks during their studies into account - the '20206' rule: every 20 minutes of close-up activity, 20 seconds of rest looking at more than 6 metres - and to combine these with plenty of outdoor activities.
The study is well-designed and assumes a very large number of individuals, both in phase 1 and phase 2. It is true that the number of individuals in phase 1 is three times smaller than in phase 2 and the latter do not have the measured graduation that could present a certain imbalance, but the analyses carried out have already taken these limitations into account and the results are very robust.