Commonly used glasses mainly use lenses, prisms, contact lenses, etc. to correct vision to achieve the purpose of eliminating visual fatigue and protecting or treating eyes. There are many types of glasses. Optical glasses and contact glasses are mainly used to correct refractive errors.
Correction of myopia:
A concave lens with proper focal power should be worn to make the light diverge properly through the concave lens, and then form a clear image on the retina after being refracted by the eye.
Correction of hyperopia:
A convex lens with proper focal power should be worn, so that the parallel rays in the distance can be properly converged by the convex lens, and then refraction by the eye to form a clear image on the retina.
Correction of astigmatism:
Varies depending on the type of astigmatism. For simple hyperopic astigmatism, a convex cylindrical lens with appropriate power and a certain axis should be worn; for simple myopic astigmatism, a concave cylindrical lens with appropriate power and a certain axis should be worn; for complex astigmatism, the power and axis should be worn Appropriate convex-convex (or concave-concave) compound cylindrical lens; for mixed astigmatism, you should wear a cylindrical lens compound of appropriate power and appropriate axial convex-concave.