Miopia: Fattori di Rischio
There are around 2.6 billion people with shortsightedness or myopia, this number is predicted to rise to around 4.9 billion by 2050. Myopia development is now understood to result from a complex interaction between visual and environmental conditions as well as genetic factors that control eye growth. Having one parent with myopia there is a 1 in 3 chance of a child becoming myopic. If both parents have myopia, then there is a 1 in 2 chance of the child developing myopia. Although genetics play a role in the development of myopia, research shows that our genes alone are not responsible for the recent increase in myopia within the population. Environmental factors, play a key role in preventing the onset of myopia. For example, the chance of developing myopia is reduced by 50% with 90 minutes of daily outdoor activity. Another environmental factor is the amount of near work. Time spent performing near activities and years of education, is related to a higher risk for myopia. Children should be encouraged to read on their lap at least 30cm away and not to read for longer than 45 minutes at a time. This time also includes the use of digital devices which according to recent studies is more than 3 hours a day for mobile devices. There are also eye related factors that have been found to be related to the onset of myopia. In general, if your child has only a small degree of hyperopia, or longsightedness, at the age of 6, then there is a greater risk of developing myopia. New technology to measure the length of the eye can also be used to predict the onset of myopia. The length of the eye, for a given age, can be compared to growth curves in order to predict the level of myopia in the future. Fortunately, your eye-care professional can assess myopia risk factors and measure axial length as part of your myopia management consultation. In general, children should at the very least undergo annual examinations, with a least one cycloplegic examination where drops are used to relax the eyes' focus.