Abstract: Water-soluble borate-polyol complexes are useful as buffers and/or antimicrobials in aqueous ophthalmic compositions, including those containing polyvinyl alcohol. These compositions have greater antimicrobial activity than comparable compositions containing typical borate buffers and unexpectedly increase the antimicrobial efficacy of other antimicrobial agents when used in combination. In addition, use of the borate-polyol complexes avoids the incompatibility problem typically associated with the combination of borate buffer and polyvinyl alcohol; therefore, the compositions disclosed herein may also contain polyvinyl alcohol.