What is the difference between spherical and cylindrical refractory error

What is the difference between spherical and cylindrical refractory error

Spherical is simple myopia or hypermetropia and cylindrical means different refraction in different axis that is astigmatism. A correction in cylindrical can also be corrected by spherical by changing axis…

Spherical is a defect in the Lens

Cylindrical is with Cornea.

Both are related to deformity in Shape and Curvature, leading to image being formed ahead and beyond retina (myopia and hypermetropia respectively)

You can correct by Convex/Concave lens.