Bayer has agreed to acquire Perfuse Therapeutics for up to $2.45 billion, the German pharmaceutical giant's biggest deal in years. The San Francisco-based eye-drug developer is working on an experimental treatment for glaucoma and diabetic retinopathy currently in mid-stage clinical trials. Bayer will pay $300 million upfront, with the remainder contingent on hitting development, regulatory and commercial milestones.

The acquisition strengthens Bayer's position in ophthalmology at a critical time. Eye drug Eylea was the company's top-selling pharmaceutical product last year, but it now faces pricing pressures after losing patent protection. Perfuse's lead candidate has the potential to become one of the first disease-modifying treatments for both glaucoma and diabetic retinopathy, according to Bayer.

The deal reflects Bayer's strategy to replenish its pharma pipeline as key products age. Acquiring Perfuse leverages Bayer's existing ophthalmology footprint while adding a potentially transformative therapy in areas of high unmet need.