Eye astigmatism can be categorized into two types: curvature astigmatism and index astigmatism, which may be related to congenital factors and corneal diseases.
1. Curvilinear astigmatism: Inconsistency in the curvature of the two major corneal diameters is the cause of regular astigmatism, which is mostly related to congenital factors. Some patients also have irregular astigmatism due to conical cornea, scarring after corneal inflammation, and peripheral corneal degenerative disease. In addition to the above, eye surgery or eyelid swelling can also cause irregular astigmatism.
2. Exponential astigmatism: Exponential astigmatism often occurs when the refractive index of each part of the lens is unequal, such as cataract in progress, the general degree of astigmatism is slight.
Ageing, malnutrition, and poor eye habits are risk factors for astigmatism. It is recommended that people with astigmatism consult a doctor for further detailed examination to clarify the cause of the astigmatism, so that they can cooperate with the doctor’s treatment to improve their condition.