preservative systems which may be incorporated into aqueous compositions for the wetting and re - wetting of contact lenses and especially silicone copolymer and soft contact lenses are provided . the perservative system includes trimethoprim , a salt of edta and sorbic acid or ascorbic acid as adjuvant bactericides . the use of preservatives which are known to cause eye irritation , such as thimerosal , benzalkonium chloride and chlorhexidine is eliminated . wetting and re - wetting compositions which incorporate the preservative system and include thickening and wetting agents are also provided . the wetting and rewetting solutions can be instilled directly into the eye during contact lens wearing periods and are especially useful for wetting silicone copolymer contact lenses . a method of wetting silicone copolymer lenses is also provided .