Abstract: Adding an aliphatic dicarboxylic acid or a salt thereof with an inorganic base to a conventional eye drop solution has been found to extend the dwell time of the solution when applied to the surface of the eye. Thus, Applicants' method of extending dwell time of conventional eye drops applied on the surface of an eye, includes providing an eye drop solution with an additive in an amount effective to extend the dwell time of the eye drop solution on the surface of an eye, the additive including at least one substance selected from the group consisting of an aliphatic dicarboxylic acid having a general formula (CH.sub.2).sub.6-9.(COOH).sub.2 and a salt of an aliphatic dicarboxylic acid having a general formula (CH.sub.2).sub.6-9. (COOH).sub.2 with an inorganic base.