The products include COSOPT, COSOPT PF, TRUSOPT, TRUSOPT PF, TIMOPTIC, TIMOPTIC PF, TIMOPTIC XE, SAFLUTAN and TAPTIQOM.
The company said that annual sales of these ophthalmology products in these territories are about $400m.
Merck president of Hospital and Specialty Care Jay Galeota said the decision to divest the company’s ophthalmics business is part of its ongoing strategy to sharpen its commercial focus and improve its operational effectiveness.
"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," Galeota said.
As part of the deal, Santen will make an upfront payment of about $600m and additional payments based on defined sales milestones as needed.
Santen will also receive supply of the ophthalmology products from Merck under this agreement for a two- to five-year period.
The deal is subject to certain closing conditions, including obtaining antitrust clearance in Japan and other closing conditions related to specific markets or regions.
Funding for the transaction will be done by Santen in a combination of cash on hand and bank loans.