The term "sphere" means that the correction for nearsightedness or farsightedness is "spherical," or equal in all meridians of the eye. Cylinder (CYL). This indicates the amount of lens power for astigmatism. Cylinder power always follows sphere power in an eyeglass prescription.
Correspondingly, what is cylindrical error in eyes?
Types of ametropia include myopia, hyperopia and astigmatism. They are frequently categorized as spherical errors and cylindrical errors: Spherical errors occur when the optical power of the eye is either too large or too small to focus light on the retina. People with refractive error frequently have blurry vision.
What do you mean by cylindrical lens?
A cylindrical lens is a lens which focuses light into a line instead of a point, as a spherical lens would. The curved face or faces of a cylindrical lens are sections of a cylinder, and focus the image passing through it into a line parallel to the intersection of the surface of the lens and a plane tangent to it.