The Four Refractive Errors

The Four Refractive Errors

If you use prescription eyewear, then you have at least one of these issues.

Our eyes are amazing organs. They work by processing light and sending electrical signals to our brains, where they become the images we see. But when our eyes lose the ability to absorb light properly, our vision suffers.

The most common cause of poor vision happens when your eye warps out of shape and light doesn’t hit your retina properly. This is known as a refractive error.

Over 150 million Americans – nearly half the country – live with a refractive error. There are four in total, each one having a unique effect on our vision.


Myopia, also known as nearsightedness, is the refractive error that makes distant objects appear blurry. When the cornea is curved too much or the eye is too long, the retina is able to only focus on light in the front. This results in clarity of sight at close range and difficulty seeing things further out. For example, people with myopia can read a book without any issue, but they would have to squint and move closer to read a sign across the street. Myopia interferes with many everyday activities, such as driving a car, playing sports, and even walking down the street.


Hyperopia, also known as farsightedness, is the opposite of myopia. With this refractive error, objects that are close by appear blurry, and things in the distance are clear. Hyperopia occurs when the cornea is curved too little or the eye is too short, causing light to focus behind the retina and distorting nearby objects. People with hyperopia can read a chalkboard from the back of the classroom without issue, but they would struggle to see the text of a newspaper held right in front of them. Like myopia, hyperopia interferes with various daily tasks, like reading, using a computer, applying cosmetics, and more.


Astigmatism is the result of an abnormal curvature of either the cornea or lens. When this occurs, light isn’t refracted to your retina properly, causing your vision to blur. Because astigmatism has the same cause as the other refractive errors, it is often accompanied by myopia, hyperopia, or in some cases, both. Other than blurred vision, symptoms of astigmatism include squinting to see, eye strain, headaches, and difficulty seeing at night.


Presbyopia is the natural deterioration of your vision that makes it hard to see nearby objects (the word is literally Greek for “old eyes”). Sounds similar to hyperopia, doesn’t it? The difference is that hyperopia can appear as early as childhood, whereas presbyopia is specifically caused by aging. Presbyopia affects people who are middle-aged and older, normally appearing no earlier than age 40 and worsening in your 50s and 60s. The effects are identical to hyperopia – a hindered ability to read, use digital screens, and perform any other close-range activities.

Refractive errors may be inevitable for many of us, but that doesn’t mean you have to let them stand in the way of your everyday life. If you’re experiencing blurred vision, then you should seek out an eye exam immediately. Our optometrists at Sterling Vision are experts at diagnosing and treating each of the refractive errors. To schedule an appointment with us, call 541-262-0597 or schedule online.