Water is the lifeblood of all ophthalmic solutions. Water of the highest purity is necessary not only to ensure medical safety, but to maintain quality as well. In the course of producing our prescription and over-the-counter ophthalmic pharmaceuticals, Santen only uses water that has been subject to a series of purification steps including physical processing, chemical processing, ion-exchange treatment, ultrafiltration(*1) and distillation. The purity of the water we use meets the exceptionally strict standards stipulated by the Good Manufacturing Practice (GMP)(*2) for water-for-injection products. Our focus on attaining the highest level of quality is also exemplified by how we use purified water to clean and sterilize our manufacturing facilities including solution tanks, pipes connecting production lines and other types of equipment.