What do astigmatism and flash mean respectively? Two kinds.

Because the refractive power of each meridian of the eyeball is different, external light cannot form a clear image on the retina, which is called astigmatism. Astigmatism patients can't see clearly, as if they have double images, swollen eyes, headache, tears, and heart vomiting; Sometimes the fundus optic disc is vertical oval with blurred edges, and the bottom limit can't be seen clearly with the follow-up mirror. If there are no obvious symptoms, there is no need to correct mild astigmatism. If there are symptoms, you should wear a cylindrical mirror to correct it. The causes of astigmatism are as follows:

(1) The radius of curvature of each meridian of secondary cornea and lens is different, and the radius of curvature of horizontal meridian and vertical meridian is usually the biggest difference.

(2) Corneal lens diseases, such as keratoconus, corneal cloud, early senile cataract, etc.

As for the flash you said. When can I buy it again? There are many reasons for this. For example, it is normal to turn on the fluorescent lamp before going to bed at night and close your eyes after turning off the lights.