BRUSSELS, March 12 (Reuters) - Belgian biotech group ThromboGenics made a net loss last year as it struggled to build up U.S. business for its main eye drug Jetrea, the company said on Thursday.

ThromboGenics said it treated 3,200 U.S. patients with the drug that treats vitreomacular adhesion, which can lead to blindness, against 7,000 patients in 2013.

The group said the drop was because of perceived safety concerns in the medical community and uncertainty about the future strategy of the company.

For 2015 ThromboGenics said it expects sales to rise but remain well below 2013 levels, targeting the sale of 3,500 to 4,000 vials of Jetrea.

ThromboGenics made a net loss of 51.1 million euros ($54.18 million) last year, against a net profit of 26.4 million euros in 2013, which included a 90 million euro gain from a partnership agreement for sales in Europe.

While its cash position fell to 127.1 million euros from the 172.4 million at the end of 2013, the group said it is confident it will have sufficient resources to continue its Jetrea sales drive in the United States. ($1 = 0.9431 euros) (Reporting by Robert-Jan Bartunek; Editing by David Goodman)