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 synthes is 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 illu strated and their properties compared to other commercially available lense s. Materials with comparatively low modulus (<0.3 MPa) and adequate tear st rength (>2-4 MPa) with excellent elongation to break (>200%) can be obtaine d using this technology. In addition to the mechanical aspects, both the ox ygen and solute permeabilities of the material can be controlled by the hyd rophilic: hydrophobic monomer balance in the formulation, to obtain materia ls with attributes suitable for extended wear use. The PC coating is achiev ed 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 b oth improved lens wettability (advancing contact angle of approximately 50 degrees with virtually no hysteresis) and lower protein adsorption relative to the uncoated lens. (C) 2001 Elsevier Science Ltd. All rights reserved.