What Is the Difference Between Regular and Irregular Astigmatism?

Can someone please explain what the difference is between regular and irregular astigmatism is? I have a presentation about astigmatism for my anatomy and physiology class but I don’t really understand the online definitions and so I would appreciate it if anyone could explain. Thank you!

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  1. Regular astigmatism means that the persons cornea has one meridian steeper than the meridian 90 degrees away from it. We often describe it as looking like the side of a football but it is actually a section out of a geometric solid called a torus. That is why contacts for astigmatism are called toric. Regular astigmatism can be corrected with glasses, soft lenses, rigid lenses or refractive surgery. The surface of a cornea with regular astigmatism could be described by a mathematical formula.

    Irregular astigmatism is any other shaped cornea besides a sphere or what i described as regular astigmatism. Some causes of irregular astigmatism are keratoconnus, a condition where a cone develops on the cornea, trauma and corneal transplants. People with irregular astigmatism often must wear rigid contact lenses to see well. The front surface of the contact replaces the front surface of the eye and the space between the eye and the lens fills with tears making up part of the prescription.

    Astigmatism just means that light does not focus at a point.

  2. Regular astigmatism is usually congenital. The meridians of the highest and least powers are perpendicular to each other. In irregular astigmatism, these meridians are not perpendicular.

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