Columnar -0.50 means that there is 50 degrees of myopic astigmatism, but generally myopic astigmatism has a specific axis, usually myopic astigmatism is cis-regular astigmatism, i.e. the axis of astigmatism is at 180 degrees. However, some people may have antegrade astigmatism, where the axis of astigmatism is around 90 degrees. Others have oblique astigmatism, where the axis of astigmatism is around 45 degrees and 135 degrees. If the astigmatism is cis-regular 50 degrees, it usually has less impact on vision and may only affect the clarity of seeing distant objects at night, and less impact on vision during the day. However, oblique and retro-regular 50 degree astigmatism may have a greater impact on vision and usually requires glasses to improve vision, especially at night. If the 50 degree astigmatism glasses are removed, the vision will be very much affected.