The Stokes lens also known as variable power cross cylinder lens, in its standard version, is a lens combination consisted of equal but opposite (one plano-convex and other plano-concave) power cylindrical lenses attached together in a way so that the lenses be rotated in opposite directions.
[4][5] American ophthalmologist Edward Jackson revised the Stokes lens concept and made a cross cylinder lens to refine power and axis of astigmatism.
[2] This lens combination is known as Jackson cross cylinder.
[2] Based on the Stokes lens, James P. Foley and Charles E. Campbell made a variable power astigmatic lens which is combination of two identical cylindrical powers instead of equal and opposite powers.
[2][6] In 1837, English mathematician and astronomer George Biddell Airy invented the cylindric lens and used it to correct astigmatism.