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2. Jackson cross cylinder - Wikipedia

   en.wikipedia.org/wiki/Jackson_cross_cylinder

   This lens consisted of two cylindrical lenses, one plano-convex and one plano-concave, which be rotated in opposite directions. In 1887 Edward Jackson described the use of modified Stokes' lens in detecting astigmatism, and in 1907 he described the determination of the axis of a correcting cylinder in astigmatism using a cross cylinder. [7]

3. Cylindrical lens - Wikipedia

   en.wikipedia.org/wiki/Cylindrical_lens

   Cylindrical lenses are prescribed to correct astigmatism. [2] Cross cylinder, which is a combination of two cylindrical lenses with equal strength and opposite power, is used in subjective refraction to diagnose astigmatism, and assess the strength and axis of the astigmatic power etc. [3] Maddox rods, made up of cylindrical lenses arranged in ...

4. Astigmatism (optical systems) - Wikipedia

   en.wikipedia.org/wiki/Astigmatism_(optical_systems)

   Astigmatism can be often corrected by glasses with a lens that has different radii of curvature in different planes (a cylindrical lens), contact lenses, or refractive surgery. [5] Astigmatism is quite common. Studies have shown that about one in three people suffers from it. [6] [7] [8] The prevalence of astigmatism increases with age. [9]

5. Stokes lens - Wikipedia

   en.wikipedia.org/wiki/Stokes_lens

   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 ...

6. Astigmatism - Wikipedia

   en.wikipedia.org/wiki/Astigmatism

   Toric intraocular lenses can additionally be used in patients with complex ophthalmic history, such as previous ophthalmic surgery. [32] In such complex cases, toric intraocular lenses seem to be as effective as in non-complex cases for correction of concurrent corneal astigmatism. [32]

7. Eyeglass prescription - Wikipedia

   en.wikipedia.org/wiki/Eyeglass_prescription

   A spherical lens has the same curvature in every direction perpendicular to the optical axis. Spherical lenses are adequate correction when a person has no astigmatism. To correct for astigmatism, the "cylinder" and "axis" components specify how a particular lens is different from a lens composed of purely spherical surfaces.