Causes of Myopia

But in a myopic eye, the eyeball is usually too long from front to back. This causes light rays to focus at a point in front of the retina, rather than directly on its surface. This makes distant objects blurry.

Myopia can also be the result of a cornea that is too curved for the length of the eyeball or a lens that is too thick. For some people, their myopia may be caused by a combination of problems in the cornea, lens, and length of the eyeball.

Source: NEI (NIH)1

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Back to: « Myopia

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Why does the eyeball grow too long?

What causes the eyeball to grow too long isnít completely known, but researchers are exploring a number of factors. For many people, myopia appears to be an inherited condition - in other words, if you have a parent with myopia you are at higher risk for developing it. Researchers are also looking at the effects of sex, age, ethnicity, and environmental exposures - such as sunlight and the amount of time spent doing close-up work - on the development of myopia. More recently, scientists have been considering the influence of circadian rhythms (sometimes referred to as our biological or body clock), which regulate systems in the body according to the daily cycles of light and dark, as a factor in the development of myopia.

Source: NEI (NIH)2

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In the past, people thought children might become myopic from spending too much time reading and writing, which require close-up vision, or from reading in poorly lit rooms. Recent studies, however, suggest that the increase of myopia in children could be related to a decrease in the amount of time they spend outdoors.

Source: NEI (NIH)3

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When you look at an object, the light rays of that object pass through the cornea and the lens of the eye. These bend (refract) the light and focus it on the light-sensitive tissue at the back of the eye (the retina). If you have perfect vision, the rays focus directly on the surface of the retina. In a myopic eye, the eyeball is usually too long from front to back. This causes light rays to focus at a point in front of the retina, rather than directly on its surface. This makes distant objects blurry.

Myopia can also be the result of a cornea that is too curved or a lens that is too thick. For some, myopia may be caused by a combination of these problems.

What causes the eyeball to grow too long isnít completely known, but NIH-funded researchers are exploring several possibilities. For many people, myopia appears to be inherited, so if you have a parent with myopia, youíre at increased risk for developing it yourself.

Source: NIH News in Health (NIH)4

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Cause

Short-sightedness is caused by your eyeball being too long or your cornea (the transparent layer that covers the front of your eye) being too curved. The focus point is in front of your retina, the light-sensitive part of your eye, rather than directly on your retina, causing blurred distance vision.

Source: New Zealand Health5

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What causes short-sightedness?

Short-sightedness usually occurs when the eyes grow slightly too long.

This means that light doesn't focus on the light-sensitive tissue (retina) at the back of the eye properly. Instead, the light rays focus just in front of the retina, resulting in distant objects appearing blurred.

It's not clear exactly why this happens, but it often runs in families and has been linked to focusing on nearby objects, such as books and computers, for long periods during childhood.

Ensuring your child regularly spends time playing outside may help to reduce their risk of becoming short-sighted.

Read more about the causes of short-sightedness.

Source: NHS Choices UK6

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Causes

Short-sightedness (myopia) usually occurs when the eyes grow slightly too long, which means they're unable to produce a clear image of objects in the distance.

It's not clear exactly why this happens, but it's thought to be the result of a combination of genetic and environmental factors that disrupt the normal development of the eye.

Source: NHS Choices UK7

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How the eye works

Light passes through the cornea (transparent layer at the front of the eye) and into the lens (transparent structure that sits behind the cornea), which focuses it onto the retina (layer of light-sensitive tissue at the back of the eye) to create an image that's sent to the brain.

To produce a perfectly clear image, the cornea should be evenly curved and the eye needs to be the right length.

In people with short-sightedness, the eye has usually grown slightly too long. This means that when you look at distant objects, the light is not focused directly onto your retina, but a short distance in front of it. This results in a blurry image being sent to your brain.

Source: NHS Choices UK8

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Marfan syndrome: Other possible eye-related symptoms of Marfan syndrome include:

  • myopia - short-sightedness

Source: NHS Choices UK9

Causes of Myopia

Causes of the condition may include:10 Causes of Myopia:

Causes List for Myopia

Some of the possible causes of Myopia or similar disorders may include:11

... Full Causes List for Myopia »

Genetics of Myopia

Degenerative myopia (also called pathological or malignant myopia) is a rare and mostly inherited type of myopia that begins in early childhood. ...Source: NEI (NIH)12 ...

... More on Genetics »

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References

  1. Source: NEI (NIH): nei.nih.gov/ health/ errors/ myopia
  2. ibid.
  3. ibid.
  4. Source: NIH News in Health (NIH): newsinhealth.nih.gov/ issue/ jul2016/ feature2
  5. Source: New Zealand Health: health.govt.nz/ your-health/ conditions-and-treatments/ diseases-and-illnesses/ eye-and-vision-problems/ refractive-eye-conditions-problems-focusing-your-eyes/ short-sightedness-myopia-or-nearsightedness
  6. Source: NHS Choices UK: nhs.uk/ conditions/ Short-sightedness/ 
  7. Source: NHS Choices UK: nhs.uk/ conditions/ short-sightedness/ causes/ 
  8. ibid.
  9. Source: NHS Choices UK: nhs.uk/ conditions/ marfan-syndrome/ symptoms/ 
  10. Source: Human Phenotype Ontology
  11. Source: Algorithmically Generated List
  12. Source: NEI (NIH): nei.nih.gov/ health/ errors/ myopia

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Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.