As the major cause of Astigmatism is genetics, astigmatism is a lifelong condition unless you correct the condition with refractive surgery.
The long term implications of astigmatism if you don’t receive refractive surgery is that astigmatism may worsen over time, increasing your risk of developing keratoconus.
Keratoconus is a condition where the cornea becomes progressively thinner. In this case, you will be at risk of needing a corneal transplant.