Cream together butter and sugar. Add eggs, and mix well. Drain pears, reserving pear juice. Puree pears in a blender or food processor. Stir pear puree and 1/3 cup reserved pear juice (with lime if desired) into sugar mixture.
Meanwhile, in a small bowl, stir pear juice into powdered sugar in small amounts, stirring well. The glaze should be a thick liquid.