A Novartis logo is pictured on its headquarters building in Mumbai April 1, 2013. REUTERS/Vivek Prakash/File Photo

(Reuters) - Swiss drug maker Novartis AG said on Tuesday it had reached a definitive agreement to acquire Fort Worth, Texas-based Encore Vision, which is focused on developing a novel treatment in presbyopia, or far-sightedness.

“There is a large need for innovative, effective and safe treatment options for people with presbyopia, and there is currently no disease-modifying treatment available at all,” Vasant Narasimhan, Novartis’ global head, drug development and chief medical officer said in a statement.

Financial details of the transaction were not disclosed.

Separately, negotiations started in November by Basel-based Novartis to acquire U.S. generics maker Amneal Pharmaceuticals LLC for as much as $8 billion have ended unsuccessfully, according to a person familiar with the situation who requested anonymity because the matter is confidential. Novartis and Amneal did not respond to requests for comment.

Novartis Chief Executive Joe Jimenez is in the process of refreshing the group’s drugs portfolio to help return the company to sales growth.

The expiration of patents on Novartis’s best-selling medicine Glivec in the United States this year and Europe next year is putting pressure on sales as generics hit the market.

But the world’s biggest maker of prescription drugs has high expectations for investigational multiple sclerosis medicines including BAF312 and CJM 112, as well as ofatumumab that it bought from GlaxoSmithKline Plc last year.