To provide a preventive and therapeutic agent for eye diseases and various means for developing the same.

A method for screening a compound having lacritin activity by using lacritin receptor expression cells mediating lacritin expression; a lacritin amplifier containing the lacritin receptor expression cells mediating the lacritin expression; a lacritin expression regulator containing lacritin, a lacritin expression vector, the lacritin expression cells, the compound having lacritin activity, a lacritin inhibitor, a lacritin inhibitor expression vector or lacritin inhibitor expression cells; a method for regulating the lacritin expression using the lacritin receptor expression cells mediating the lacritin expression; a method for identifying or producing the lacritin receptor expression cells mediating the lacritin expression; and a kit including the lacritin receptor expression cells mediating the lacritin expression, or the like are provided.