How does the doctor measure the correction power for astigmatism?

[La Pryor]

I am wondering how they find out the correction power is needed for astigmatism? Is there any difference from how they test for myopia?

[La Puente]

If you have astigmatism then the axis will show up as distortion in one or several of the rays of the Astigmatic Mirror above. The angle of the major distortion is indicated on the chart. People with natural clear vision see all the lines in the same thickness and exactly the same spacing between the lines. Look at the Astigmatism chart from several distances and notice where the distortion begin and ends. It is possible to have astigmatism only at the near, or only at the distance, or at any plane in between. Download the Acrobat file and print a chart in with the background colour you like the best. Set your printer to the highest print quality as possible. The Astigmatic Mirror provide an accurate feedback concerning your astigmatism.

[La Push]

First, the doctor will give you Using a standardized chart to test your vision. Then the doctor will use a retinoscope to determine whether you have refractive error or not. Then the doctor will use keratometry to measure the curvature of your central cornea and then they determine whether you have astigmatism or not. Finally, he will ask you whether you can see the chart clearly with the corrective lenses.