A novel phosphorylcholine-coated contact lens for extended wear use

The preparation and characterisation of a new phosphorylcholine (PC)-coated silicone hydrogel contact lens for use in extended wear is described. The Michael-type addition of amines to acrylates forms the basis of the synthesis of a novel silicone-based macromer with hydrophilic functionality. It is demonstrated that this macromer can be combined with other silicone-based monomers, hydrophilic monomers and crosslinker to produce a contact lenses formulation. Examples of lenses with water contents of 33% and 46% are illustrated and their properties compared to other commercially available lenses. Materials with comparatively low modulus (<0.3 MPa) and adequate tear strength (>2–4 MPa) with excellent elongation to break (>200%) can be obtained using this technology. In addition to the mechanical aspects, both the oxygen and solute permeabilities of the material can be controlled by the hydrophilic : hydrophobic monomer balance in the formulation, to obtain materials with attributes suitable for extended wear use. The PC coating is achieved by means of an in-mould coating (IMC) technique that produces a uniform and stable surface as determined by staining and XPS. The coating imparts both improved lens wettability (advancing contact angle of approximately 50° with virtually no hysteresis) and lower protein adsorption relative to the uncoated lens.