Astigmatism below 300 degrees generally can be corrected with orthokeratology (OK) lenses. Astigmatism is a type of refractive error where the eye has different refractive powers in different meridians, causing parallel light rays passing through the eye's refractive system to refract improperly and form two focal lines instead of a single focal point on the retina, resulting in a blurred image. Astigmatism can be categorized into regular astigmatism and irregular astigmatism. Regular astigmatism can be corrected using cylindrical lenses or glasses, while irregular astigmatism may require correction with corneal contact lenses, OK lenses, or surgical correction. Common symptoms of astigmatism include blurred vision, reduced visual acuity, and easy eye fatigue, and sometimes may also present with symptoms such as head tilting and headaches. Therefore, it is advisable to seek consultation in the ophthalmology refractive department if astigmatism symptoms appear.