Santen Pharmaceutical has purchased Merck's ophthalmology products in Japan and key markets in Europe and Asia Pacific.

"The decision to divest our ophthalmics business is part of our ongoing strategy to sharpen our commercial focus and improve our operational effectiveness," said Jay Galeota, president, hospital and specialty care, Merck. "This transaction provides products that complement Santen's portfolio and is designed to ensure continued access for physicians and patients to these medicines around the world."

Santen will make an upfront payment of approximately $600 million and additional payments based on defined sales milestones as needed. The annual sales of these ophthalmology products in the markets within the scope of the agreement are approximately $400 million. Santen also will purchase supply of the ophthalmology products covered by this agreement from Merck for a two- to five-year period. The agreement is subject to certain closing conditions, including obtaining antitrust clearance in Japan and other closing conditions related to specific markets or regions. The agreement is expected to close in most markets in a few months.

Merck divested its U.S. ophthalmology business to Akorn Pharmaceuticals in 2013 and 2014. Merck will continue to sell its ophthalmology products in Latin America, Canada, Australia, the Middle East and Africa.