Astigmatism is a very common vision disorder that occurs when the shape of the cornea is either not spherical or not regular. It is a stand-alone problem, but is often accompanied by short-sightedness or farsightedness. If the curvature of the cornea is irregular, our eyes cannot gather light into a focal point, which results in blurred and distorted vision regardless of the distance of the objects. It is difficult to clearly distinguish between objects, letters and their details. Letters of similar shape, such as H, N, M, U are easily mixed up.