Deformable Membrane Assemblies

A deformable membrane assembly comprising a fixed support, a fluid-filled envelope, one wall of which is formed by an elastic membrane that is held under tension around its edge by a flexible membrane supporting member, the supporting member being coupled to the fixed support at a plurality of discrete control points around the supporting member by engaging members for controlling the position of the membrane edge; and an adjuster for adjusting the pressure of the fluid within the envelope to adjust the shape of the membrane; wherein at least three control points are provided that are situated around the membrane edge at spaced locations selected to increase the energy of the lowest order out-of-plane bending mode of the supporting member while allowing the membrane to deform according to one or more selected Zernike polynomials. An article of eyewear comprising such a deformable membrane assembly is also disclosed.