High astigmatism is usually caused by two factors: first, congenital corneal irregularities, which cause astigmatism that is usually large and irregular in shape. The second is due to acquired corneal diseases, such as corneal inflammation, corneal ulcers, etc., which may result in a large degree of astigmatism when the inflammation is repaired and localized scarring or scarring after corneal trauma is formed. This type of astigmatism is usually very irregular, so it is difficult to improve the vision to the normal range with conventional frame glasses or corneal contact lenses, and it is generally recommended to choose surgical treatment.