cylindrical lens is a lens which focuses light which passes through on to a line instead of on to 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 onto a line parallel to the intersection of the surface of the lens and a plane tangent to it. The lens compresses the image in the direction perpendicular to this line, and leaves it unaltered in the direction parallel to it (in the tangent plane).

Cylindrical lenses can be used to correct ocular astigmatism, although toric lenses are more commonly used. They can also potentially be used in solar water heating installations, such as a plastic pillow-type solar water heater. They are used to correct the output from diode lasers, to produce a round beam from the diode's elliptical output