{"id":391,"date":"2022-12-07T15:36:23","date_gmt":"2022-12-07T20:36:23","guid":{"rendered":"https:\/\/www.warbyparker.com\/learn\/?p=391"},"modified":"2026-04-02T03:12:22","modified_gmt":"2026-04-02T07:12:22","slug":"what-is-astigmatism","status":"publish","type":"post","link":"https:\/\/www.stage.warby.io\/learn\/what-is-astigmatism","title":{"rendered":"What Is Astigmatism, and Can It Be Corrected?"},"content":{"rendered":"\n

Astigmatism is an uneven curvature of the eye\u2019s cornea or lens. It\u2019s a very common eye condition\u2014about one in three Americans<\/a> have it. Although it can cause inconvenient vision problems, including blurry vision and poor eyesight at night<\/a>, it\u2019s typically very treatable. Often, all you need is a new pair of glasses<\/a> or contact lenses<\/a>. <\/p>\n\n\n\n

Read on for more details on the definition of astigmatism, its symptoms, and how eye doctors can diagnose and correct it.  <\/p>\n\n\n\n

What Does it Mean to Have Astigmatism?<\/h2>\n\n\n\n

Think of your cornea as a clear, rounded dome over the surface of your eye. In people with astigmatism, that dome isn\u2019t perfectly rounded\u2014it\u2019s shaped more like an egg or a football. The irregular shape of the cornea affects how light is focused inside the eye.<\/p>\n\n\n\n

An evenly round cornea (without astigmatism, as seen below) focuses light rays into a single point on the retina at the back of the eye, producing a clear image.<\/p>\n\n\n\n\n\n

But an unevenly shaped cornea can\u2019t focus light with the same precision. It bends the light so it hits multiple points on the retina instead of just one, resulting in blurred vision at all distances. Here\u2019s how that looks:<\/p>\n\n\n\n\n\n

Astigmatism, like myopia (nearsightedness)<\/a> and hyperopia (farsightedness)<\/a>, is a kind of refractive error. Refractive errors occur when the shape of the eye keeps light from focusing properly to a single point on the retina. <\/p>\n\n\n\n

Refractive errors are responsible for a host of common vision problems, and they can even coexist: Astigmatism may not be the only refractive error present in a given eye! It\u2019s possible to have astigmatism and nearsightedness, for example.<\/p>\n\n\n\n\n\n

Types of Astigmatism <\/h2>\n\n\n\n

Chances are, astigmatism in your eye won\u2019t be exactly the same as astigmatism in another person\u2019s eye\u2014and you can also have different astigmatism corrections in each of your own eyes! Corneas (and lenses) can curve in many different ways. That\u2019s why optometrists<\/a> sort astigmatisms into types based on the part of the eye they affect and the nature of their shape.<\/p>\n\n\n\n

Corneal vs. Lenticular Astigmatism<\/h3>\n\n\n\n

Astigmatism can affect the cornea or, less commonly, the lens of the eye. People with corneal astigmatism have an irregularly shaped cornea, whereas people with lenticular astigmatism\u2014you guessed it\u2014have an irregularly shaped lens. <\/p>\n\n\n\n

Both parts of the eye<\/a> aid in light refraction, so both types of astigmatism cause similar vision problems.<\/p>\n\n\n\n<\/div>\n\n

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With-the-Rule vs. Against-the-Rule Astigmatism<\/h3>\n\n\n\n

Optometrists group astigmatisms into two categories based on their shape: with-the-rule and against-the-rule. <\/p>\n\n\n\n

If you have with-the-rule astigmatism, which is the more widespread type, then your cornea has a steeper curve along its vertical axis. Looking at it straight on, it appears to be shaped like a football lying on its side or a sphere that\u2019s been squeezed from the top and bottom. <\/p>\n\n\n\n

Against-the-rule astigmatism, on the other hand, refers to a steeper curve along the horizontal axis. Corneas with against-the-rule astigmatism look more like a football standing on its end or a sphere that\u2019s been squeezed from the sides.<\/p>\n\n\n\n\n\n

Astigmatism Symptoms<\/h2>\n\n\n\n

How do you know if you have astigmatism<\/a>? Start by checking for some or all of the following symptoms:<\/p>\n\n\n\n