What Does LASIK Correct?

Eye Conditions Corrected with LASIK

How the Eyes Focus

The eyes focus by bending incoming light rays to meet at a single point. Ideally, this single point lands directly on the central point of the retina for clear, sharp images. If the focal point is behind the retina or in front of the retina, the image on the retina will not be fully formed and is interpreted by the brain as being blurred.

This is a refractive error. This is very much like focusing a projector onto a blank movie screen. If the projection is too close or too far from the screen, the images are blurred. When set at the correct distance, you may enjoy the show!

Refractive errors that may be corrected with LASIK include:

  • Nearsightedness
  • Farsightedness
  • Astigmatism

Nearsightedness (Myopia)

Myopia DiagramNearsighted individuals typically have problems seeing well at a distance. The nearsighted eye is usually longer than a normal eye and its cornea may also be steeper. Therefore, when light passes through the cornea and lens it is focused in front of the retina.

This will make distant images appear blurred. LASIK, PRK, implantable contact lenses, and other methods can be used to correct nearly all levels of nearsightedness.

Farsightedness (Hyperopia)

Hyperopia DiagramFarsighted individuals typically develop problems reading up close before the age of 40. The farsighted eye is usually slightly shorter than a normal eye and may have a flatter cornea.

Therefore, when light passes through the cornea and lens it is focused behind the retina. Near objects require even greater focusing power to be seen clearly and therefore blur more easily. LASIK, PRK, and other methods can be used to help correct farsightedness.


Astigmatism DiagramIndividuals with astigmatism typically experience vision where the images they see seem to be blurred or shadowed. This is caused by asymmetric steepening of the cornea or natural lens, which causes light to be focused unevenly on the retina.

Astigmatism can accompany any form of refractive error and is very common. LASIK, PRK, and other methods can be used to help correct astigmatism.

Presbyopia: Not a Refractive Error

Presbyopia DiagramPresbyopia is a condition that typically becomes noticeable for most people around age 45.

In children and young adults, the lens inside the eye can easily focus on distant and near objects. With age, the lens loses its ability to focus adequately.

Although presbyopia is not completely understood, it is thought that the lens and its supporting structures lose the ability to make the lens longer during close vision effort. To compensate, affected individuals usually find that holding reading material further away makes the image clearer.

Ultimately, aids such as reading glasses are typically needed by the mid-40s. Besides using reading glasses, presbyopia can be corrected in a number of ways. Some options include monovision with LASIK or PRK surgery, accommodating lens implants, and multifocal contact lenses.

When you have an eye exam at Harvard Eye Associates, your doctor will measure your eyes and determine whether you are nearsighted or farsighted and whether you have astigmatism and/or presbyopia. Based on the results from your eye examination, your eye doctor will discuss all the treatment options that are available to you along with the risks, benefits, and alternatives of each treatment.

Contact us today to schedule a free LASIK evaluation with one of our LASIK doctors.

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