Frequently asked questions about refractive errors

The origin of myopia is not entirely clear, but it seems that two factors play a role. On the one hand, there are genetic factors and, on the other hand, there is the fact that children are currently spending less time outside. It has been observed that primary school-aged children who spend less than 45 minutes a day outside are at greater risk of myopia than those who spend two hours outside. 

Although children now spend more time looking at screens, there is no proven link to myopia. People who spend more time in education and children who read continuously are at greater risk of being myopic, but various research studies show that time dedicated to “near tasks” does not mean the child will develop myopia. 

In the first years of life, our eyeballs grow by a few millimetres. Then, they continue to grow very slowly for a few years, and stop growing around the age of 12-13 years. In some children, the eyeball grows too much for the strength of the lens, and can continue growing after the age at which it normally ceases.  

Myopia is measured in dioptres. Usually, the change is up to an average of 0.5 dioptres per year in children and adolescents, but changes can often occur within less time, especially in children who become much taller very quickly (the “growth spurt” of puberty). 

No. Presbyopia develops progressively due to age and, as such, we cannot prevent its progression. The progression will be the same, whether or not you wear glasses. 

However, it is true that, at the start of presbyopia, we retain a certain accommodative facility, which means that we are able to improve focus by doing certain exercises, although as presbyopia progresses we will gradually lose this facility, and wearing glasses will be inevitable. 

No. These are two contradictory eye conditions. It is not possible to have myopia and hyperopia at the same time. 

Hyperopia is a lack of strength of the eye (either because it is too short, or because the lenses are not powerful enough) and myopia is an excess of strength in the eye (either because the eye is too long or because the lenses are too powerful). 

However, you can have hyperopia and astigmatism, or myopia and astigmatism. 

No. Hyperopia and presbyopia are not the same, although both are often known as “farsightedness”. 

Hyperopia is a refractive error caused by the characteristics of the eye (either because the eye is short, or because the cornea and the lens are not powerful enough, and the images are not focused on the retina, causing blurry near vision). Meanwhile, presbyopia is a difficulty focusing in near vision due to age. As of 40-45 years, the eye progressively loses its accommodative facility, causing difficulty in focusing on near objects. 

Yes. Presbyopia is caused by age, and therefore you can have hyperopia or myopia and/or astigmatism when young, and then develop presbyopia between 40-45 years.