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Myopia, Hyperopia, and Astigmatism: Understanding Refractive Errors



Most people know what it means to be near-sighted or far-sighted, and plenty are familiar with the word "astigmatism", even if some might struggle to define it. But what do these terms actually entail, and what is happening behind the lens, so to speak?





  • Myopia (near-sightedness) occurs when light coming into the eye focuses in front of the retina, rather than directly on it. This results in distance vision blur. The retina is the neural lining of the back of the eye, and acts like the film of a camera. If light does not focus directly onto the retina, the image will appear blurry. In axial myopia, the eye is longer than normal. In curvature myopia, the cornea or lens of the eye may be steeper than normal. A proper lens placed in front of the eye can refocus the image from in front of the retina to directly on it, thus making the vision clear. This is typically done with glasses or contact lenses. Reshaping the cornea to flatten it using laser surgery (Lasik) can also be effective, but this is not approved for children. Myopia is mostly genetically determined, although environmental factors, such as the amount of near work done, can also play a role.

  • Hyperopia (far-sightedness) occurs when light coming into the eye focuses behind the retina, rather than directly on it. This results in near vision blur. In cases of high hyperopia, distant objects will appear blurry as well. In axial hyperopia, the eye is shorter than normal. In curvature hyperopia, the cornea or lens of the eye may be flatter than normal. A proper lens placed in front of the eye can refocus the image from behind the retina to directly on it, thus making the vision clear. This is typically done with glasses or contact lenses. Reshaping the cornea with laser surgery (Lasik) can also be effective, but this is not approved for children. A small amount of hyperopia is normal in children. However, higher levels of hyperopia can lead to blurred vision, headaches when reading, amblyopia (lazy eye) and strabismus (crossed eyes).

  • Astigmatism occurs when light is focused unevenly on the retina. This occurs because the cornea or the lens of the eye has an irregular curvature, more like that of a football, rather than a baseball. Very small amounts of astigmatism are not uncommon, and often these patients do not require glasses. Those with higher amounts of astigmatism have blurred or distorted vision at all distances, but especially far away. Just like with myopia and hyperopia, a proper lens placed in front of the eye can even out the retinal image and make the vision clear. This is usually done with glasses or toric contact lenses. Reshaping the cornea with laser surgery (Lasik) can also be effective, but this is not approved for children.


Hopefully that clears things up (no pun intended)!


If you are concerned that you or your child might be dealing with one or more of these conditions, we recommend that you seek the attention of trained ophthalmologist, who can steer you to the proper solution.





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