Astigmatism

Contrary to what many people believe astigmatism is not a disease and it is an extremely common condition. Having astigmatism is no different from being long or short-sighted; it is just a type of prescription. Over 80% of people who wear glasses have astigmatism to some degree and it is normally combined with either long-sightedness or short-sightedness.

Depending on the degree of astigmatism you may or may not need to wear spectacles all the time. If your astigmatism is mild you may just need to wear your glasses when performing certain tasks such as reading or computer use.

Explaining Astigmatism:

If you have astigmatism, the prescription your optician issues for you will have the ‘cyl’ box filled out. This is short for cylinder and is the astigmatic component of your prescription. The following gives an example:

Sph     Cyl      Axis
-1.50    -2.00    180

The sphere component relates to whether you are long-sighted or short-sighted. In this case, as it is minus, you are short-sighted. The cyl relates to your astigmatism. In this case, it is -2.00 which is moderately astigmatic. The axis relates to the direction of your astigmatism. Astigmatism rarely goes beyond -6.00 and if it is as high as this you will require wavefront laser eye surgery.

You have probably heard your optician using the phrase ‘rugby ball shaped eye’ to explain astigmatism. With astigmatism, it is the shape of your eye that causes the blurred vision. What this means is that the curvature of your eye/power of your eye is different horizontally compared with vertically. For example, the curve of the eye horizontally might be steeper (more powerful) than the curve of the eye vertically resulting in an out of focus image. This means that instead of being completely round your eye is in fact slightly more oval-shaped (rugby ball). This is not something that can be seen with the naked eye. Generally, vision is blurred for both distance and near vision but people can tolerate different amounts of astigmatism without needing spectacles, contact lenses or laser eye surgery.

Laser Eye Surgery & Astigmatism:

Laser eye surgery treats astigmatism by equalling out the differing curvatures (powers) of your cornea and then placing them together as an image onto the retina. Astigmatism can be treated using either Lasik surgery or Lasek surgery and best results are normally achieved when combining these procedures with wavefront technology. To read more about how laser eye surgery can correct astigmatism you can read the following detailed guide: How does laser eye surgery correct astigmatism?

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