Hydrophilic-gel contact lenses adapted into a planarized xerogel state

Abstract

The invention pertains to a method of temporary planarization of hydrogel contact lenses by drying of a lens swollen in a volatile hydrophilic swelling agent and clamped in the planarized state between two surfaces, at least one of which is formed by a thin foil permeable for the hydrophilic volatile swelling agent, as long as the swelling agent diffuses through the foil and the lens is transfered into a xerogel state. According to this invention, the planarized lens may have an enlarged surface and reduced thickness in comparison with the relaxed lens and may be provided with temporary marking comprising signs or lines showing the direction of cylindric axis with toric lenses, a marginal angle scale to enable easier truncation of toric lenses, and additional specifications of the lens. The temporary marking is achieved by pressing the planarized lens during drying against a base with embosed drawing or against projections at the compression foil. According to the invention, water, C.sub.1 -C.sub.5 alcohols, formic and acetic acid, acetone, methyl ethyl ketone, and dioxan are used as the volatile swelling agents individually or in mixtures and cellophane or polyamide for permeable foils. The planarized contact lens in xerogel state may advantageously contain up to 8 wt. % of hydrophilic plasticizers, e.g. glycerol, glycolor polyglycol, to reduce the brittleness of xerogel and make easier the final adaptation of lens.