How Does Your Eye Doctor Diagnose Astigmatism?

How Does Your Eye Doctor Diagnose Astigmatism?

Astigmatism is a refractive error caused by the curvature of the eye. While other forms of refractive errors limit vision at certain distances such as nearsightedness (myopia) or farsightedness (hyperopia), astigmatism causes blurry vision at all distances. An eye doctor can diagnose astigmatism during an eye exam by determining how the shape of the cornea (the outer layer of the front of the eye) or the lens impacts where the light is reflecting on the back of the eye. Using several optical devices, your eye doctor can determine if your astigmatism is an issue with your cornea or lens as well as how to correct it with the proper prescription.


How Does Your Eye Doctor Correct For Astigmatism?

Since astigmatism is caused by the light reflecting onto the wrong part of the eye, light needs to be bent externally to alter where it will be directed in the eye. Light is bent using prescription lenses either in the form of eyeglasses or contact lenses. To determine exactly how the light needs to be bent, an eye doctor will examine the eye and measure how far light is from hitting the area on the retina it needs to hit to produce a clear image. These three tests will determine the extent of your astigmatism and will help to correct it.

  1. Topography
    A topography device, also known as a corneal topographer or a keratometer, is used to measure the shape and strength of the cornea. This device will measure the reflection of a circle of light shone into the eye and show your eye doctor how curved the cornea is on either side. Corneas that are too flat, too steep, or unevenly curved will produce blurry vision.
  2. Autorefractor
    Your eye doctor will use this device to measure where light is reflecting off the back of your eye. To produce a clear image, light needs to hit the correct spot on the retina, but when a person has a refractive error, images will focus either too far in front or too far behind the retina. Determining where light is reflecting within the eye and how far it is from where it needs to be will allow your eye doctor to determine your prescription.
  3. Phoropter
    When assessing your prescription, your eye doctor will have you look through a device with multiple changing lenses. This is the device most people associate with the eye doctor and you have likely seen it before. The device gently rests on your nose as you look through two small lenses in a larger mechanism that looks like two large circles with gears and lenses. Once your eye doctor has the phoropter positioned, they will start with one set of lenses and will change them as you tell the optometrist which lenses are more clear. Through this process, you will end up looking through a set of lenses that allow you to see clearly and this will help determine your prescription. 

Visit A Calgary Eye Doctor For Astigmatism

While many people think of refractive errors as either nearsightedness or farsightedness, astigmatism prevents clear vision at any distance. The best way to know if you or your child has astigmatism is to visit a Calgary eye doctor for an eye exam. Your Calgary eye doctor will be able to determine if you have astigmatism, how severe it is, and how to correct your vision. With the proper prescription, astigmatism can be easily corrected, resulting in clear vision. If you are ready to start seeing clearly, book an appointment with a Blink Eyewear Calgary eye doctor by calling 1-403-516-2292 or filling out the online contact form. With three convenient locations in Crowfoot in NW Calgary, West Springs in SW Calgary, and Creekside in NW Calgary, Blink Eyewear can offer you great optometry services throughout the city.

Astigmatism FAQ's

Astigmatism is caused by the growth and alignment of the eyes. It is thought to be largely genetic, although there are some cases of people developing astigmatism after an eye injury or eye surgery. In rare cases of a condition called keratoconus, the cornea becomes increasingly thin and cone-shaped, resulting in progressively worsening astigmatism and blurred vision.

While wearing corrective lenses for astigmatism will likely improve your vision, it will not reshape your eye or prevent astigmatism from getting worse. There are many benefits to wearing glasses/contacts for your vision including reducing eye strain and the headaches caused by blurry vision.


Yes, you can. Several years ago, contact lenses did not fit the curvature of most people with astigmatism, but modern technology has since overcome this barrier so that people with astigmatism can wear contact lenses. To learn more about wearing contact lenses with astigmatism, read 3 Questions To Ask Your Eye Doctor About Wearing Contacts With Astigmatism.


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Blink Eyewear boasts the largest collection of eyewear in Calgary, but our 3 locations are also home to the region’s finest optometrists. Just as you will not find a better store to shop for your eyewear, you will not find a better vision clinic to do your eye exam or treat your eye condition. 

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