Tulsi Optical

Cylindrical Power

The cylinder or cylindrical component of a spectacle prescription is an indication of the amount of astigmatism in an eye. Astigmatism is the amount that the refractive structures of the eye (primarily, the front and back surfaces of the cornea and the front and back surfaces of the crystalline lens) vary or deviate from sphericity or a spherical shape.  That is, astigmatism indicates the degree of toricity or cylindrical shape of all of the eye’s refractive components, combined. Cylinder values can be positive or negative.