There’s a lot of confusion about which eye conditions are correctable with LASIK eye surgery. As a result, we’ve heard a lot of myths over the years about who can benefit from LASIK and who can’t. We’d like to clear up the confusion! Below you’ll find the eye conditions that are treatable with LASIK.
Myopia (AKA: Nearsightedness):
In this eye condition, near objects are clear and distant objects are blurry. To see clearly, the light rays from an object need to come to a point focus directly on the retina. With nearsighted patients, the light rays from an object fall short of the retina. This is typically due to the fact that some eyes are anatomically longer in nearsighted eyes when compared to normal or farsighted eyes, so the light rays have farther to travel. This causes distant objects to be blurry which is why nearsighted patients require glasses for distance vision.
How the excimer laser corrects nearsightedness in LASIK eye surgery:
We can’t shorten the eye, but we can lengthen the distance that the light rays from that object need to travel so that they can be focused at a point directly on the retina. That’s accomplished with LASIK eye surgery by gently sculpting the cornea using an excimer laser to remove microscopic amounts of tissue centrally. This flattens the central portion of the cornea, so that the light rays come to a point focus on the correct portion of the retina. Click here to learn more about myopia (nearsightedness).
Hyperopia (AKA: Farsightedness):
The eye condition hyperopia primarily causes near objects to appear blurry. However, farsightedness isn’t as straightforward as nearsightedness, as it can also cause distant objects to appear blurry, if it’s severe enough. In an eye that is farsighted, light rays from an object will come to a point focus beyond the retina, which produces a blurry image. This is typically due to the fact that some eyes are anatomically shorter in farsighted eyes when compared to normal or nearsighted eyes, so the light rays have a shorter distance to travel.
How the excimer laser corrects farsightedness in LASIK eye surgery:
We can’t lengthen the eye, but we can shorten the distance that the light rays from that object need to travel so that they can be focused at a point directly on the retina. The way that’s accomplished with LASIK eye surgery is to gently sculpt the cornea by removing microscopic amounts of tissue in the periphery, which steepens the cornea centrally so that the light rays come to a point focus on the correct portion of the retina. Click here to learn more about hyperopia (farsightedness).
Almost all patients have some astigmatism which can cause blurry vision. The easiest way to understand astigmatism is to consider the following analogy: A cornea without astigmatism is spherically-shaped like a basketball, whereas one with astigmatism is steeper in one plane than the other, like the end of a football. The cause of astigmatism is a steepening of the cornea in one meridian or axis. In an eye with astigmatism, light rays from an object will not come to a single point focus on the retina as with nearsightedness and farsightedness. Instead, the light rays are focused at 2 different points. This causes objects at distance and near to be blurred and can also cause objects to appear elongated.
How the excimer laser corrects astigmatism in LASIK eye surgery:
The excimer laser is used to remove corneal tissue in the steeper meridian, along the axis where the astigmatism lies. This flattens the steeper part of the cornea so that the shape becomes more spherical. This brings light rays to a point-focus on the retina. Astigmatism can also be present in an eye that is nearsighted, farsighted and presbyopic.
Presbyopia causes near vision to be blurry and affects everyone as they age. It usually presents itself when patients are in their mid to late 40’s. In order to see things up close, the natural crystalline lens of the eye changes its shape. Presbyopia is a natural aging process which causes the lens of the eye to lose its elasticity so that it can’t change shape to bring near objects into focus.
How the excimer laser corrects presbyopia in LASIK eye surgery:
For patients with presbyopia, the LASIK surgical procedure is modified so that one eye is optimized for distance vision and the other for near vision tasks. Click here to read more about monovision laser vision correction. Presbyopia can be present with or without nearsightedness, farsightedness and astigmatism.
Of course, having the above conditions doesn’t automatically mean you qualify for LASIK. In order to find out if you’re a suitable candidate for LASIK eye surgery, you need to have a LASIK consultation with a corneal specialist. This includes a comprehensive eye exam as well as a detailed evaluation of your corneas and visual system. Interested in LASIK? Call us at 888-866-3681 to schedule a FREE LASIK consultation with our corneal specialist and micro-surgeon, Dr. Eric Mandel. You can also click here to book your consultation online.
Change Your Vision, Change Your Life. Mandel Vision®
Click here to return to our main blog page.