Nearsightedness, also known as myopia, is a common refractive error of the eye. It occurs when the eye fails to focus light properly, resulting in objects that are close appearing clear while those far away appear blurry. It is very common: a 2016 analysis in the journal Ophthalmology (Holden and colleagues) estimated that about 28% of the world’s population was myopic in 2010 and projected that about half would be by 2050. It usually starts in childhood and tends to progress through the teenage years.
You can learn if you have the condition with a regular eye exam, and for the best eye exam cost options that accept vision insurance, make your way to Boscov’s Optical. For now, keep reading to learn about the common causes of this condition.
Genetics
Nearsightedness runs strongly in families, and twin studies suggest that much of the difference between people is inherited. When it comes to understanding the genetics of this eye condition, the first thing to consider is the different types of myopia. Myopia can be further divided into axial and refractive myopia.
Axial myopia occurs when the eyeball grows too long, resulting in the light entering the eye being focused in front of the retina, instead of directly on it. Refractive myopia occurs when the cornea is too curved, resulting in the light entering the eye being focused in front of the retina. Both of these types of myopia can be inherited from one or both parents.
Myopia is not caused by a single gene. The original version of this article named one variant, rs1801133, as a well-known myopia gene on chromosome 15. That was wrong: rs1801133 is a variant of the MTHFR gene on chromosome 1, studied mainly for its effect on folate metabolism, not eye length. Large genome-wide studies have instead linked hundreds of genetic regions to refractive error. A 2018 meta-analysis of 160,420 people (Tedja and colleagues, Nature Genetics) identified 161, and a 2020 analysis of 542,934 people (Hysi and colleagues, Nature Genetics) raised the total to 449. Each region has only a small effect, and together the variants found so far explain about 18% of the inherited risk.
Environmental Factors
Environmental factors such as air pollution and artificial lighting can also affect the development of nearsightedness. The best-supported environmental factors are how much time children spend outdoors and how much close-up work they do: more time outdoors in daylight is consistently linked to a lower risk of developing myopia, while long hours of reading or screen use at close range are linked to a higher risk. Air pollution has also been associated with myopia in some observational studies, but that evidence is limited and the mechanism is not established.
Similarly, artificial light can disrupt the body’s circadian rhythm, resulting in the secretion of hormones that can lead to eye growth changes and the development of this eye condition. Studies have also suggested that diet may be a contributing factor in the development of this condition.
Diets low in Omega-3 fatty acids have been linked to an increased risk of myopia, as these fatty acids are essential for healthy eye development. Evidence on diet, including omega-3 intake and diets high in processed foods, comes from a small number of studies and is not strong enough to call diet a proven cause.
Your Axial Length
Nearsightedness, or myopia, is a common vision condition that affects millions of people. This condition is caused by a number of different factors, including an abnormally long axial length. When the axial length of the eye is too long, it causes the light to focus in front of the retina instead of on it.
This causes objects that are far away to appear blurry and out of focus. There are a number of ways to determine the axial length of the eye, including ultrasound and optical biometry. These methods measure the length of the eye from the front to the back.
A longer axial length is a common cause of this eye condition. It can be corrected with glasses, contact lenses, or refractive surgery. The type of correction that is best for you will depend on the severity of your nearsightedness and the shape of your eye.
Overall, nearsightedness is a very common vision problem that can have a big impact on a person’s life. It can be caused by a variety of factors, including genetics, environment, and lifestyle.
Taking steps to identify and address the underlying causes can help reduce the risk of developing this eye condition and improve a person’s vision. It is important to be aware of the possible causes and to seek professional help if needed.
