Astigmatism Is Not an Eye Disease

If you have been told you have astigmatism, the name may sound more alarming than it needs to. Astigmatism is not an eye disease. It is a common way of describing how the eye focuses light.

You might notice that letters look a little blurry, streetlights seem stretched at night, or you squint to make a sign clearer. Those experiences do not tell you on their own what is causing the blur. An eye exam can help identify whether astigmatism, another focusing difference, or something else is involved.

What eye shape has to do with focus

Think about the difference between a basketball and a football. A basketball curves about the same way in every direction. A football has a steeper curve in one direction than the other. With astigmatism, the clear front surface of the eye, called the cornea, often has curves that differ by direction. Sometimes the shape of the lens inside the eye plays a part instead.

Light bends as it passes through the cornea and lens. When those curves differ, light may not come together in one clear spot at the back of the eye. The result can be blurred or stretched-looking vision. Astigmatism can affect sight up close, far away, or both.

Why astigmatism can come with nearsightedness or farsightedness

Astigmatism is only one part of the focusing picture. Nearsightedness means distant objects tend to look blurry because light focuses in front of the retina, the light-sensitive tissue at the back of the eye. Farsightedness means the eye tends to focus light behind the retina, which can make close work harder to see clearly. How much a person notices either one can vary.

An eye can have two focusing differences at once. For example, someone may be nearsighted overall and also have a cornea that curves differently from one direction to another. It is a bit like adjusting a camera for distance while also needing to correct a lens that bends light unevenly. One issue does not cancel out the other.

That is why a glasses prescription may include numbers for nearsightedness or farsightedness and separate numbers for astigmatism. They describe different parts of how your eyes focus.

What an eye exam can tell you

Vision testing can measure how clearly you see and which lens powers help bring things into focus. An eye exam also gives your eye care provider a chance to look at the health of your eyes. That matters because blurry vision is not always caused by astigmatism.

Glasses and contact lenses can correct astigmatism for many people. The right approach depends on your eyes and your daily needs. If you have questions about your prescription or whether another type of vision correction might be appropriate, an eye care provider can talk through the options with you.

When to ask about a change in vision

Astigmatism itself is a focusing difference, but a new or sudden change in vision should not be assumed to be “just astigmatism.” Eye pain, a sudden drop in vision, or other concerning symptoms deserve prompt attention.

If your vision seems different, or you are unsure what the numbers on your prescription mean, call Ace Medical Care with your questions. Understanding how your eyes focus can make it easier to discuss what you are seeing and what to do next.

Questions about your own care? The team at Ace Medical Care is happy to help — call us at (646) 682-7544.

This article is for general information only and is not medical advice.