1-800 Contacts Inc., the Draper-based online retailer of contact lenses, has sued competitor Drugstore.com Inc. for placing Internet ads that appear when consumers look up "1-800 Contacts" in a search engine.

Drugstore.com's Vision Direct unit is infringing a trademark because its online ads show up when shoppers search for 1-800 Contacts' trademarked name, the company said in a lawsuit filed Thursday in federal court in Salt Lake City.

The ads, known as "sponsored links" on Google Inc.'s search-results pages, violate a 2004 settlement agreement between 1-800 Contacts and Vision Direct, according to the lawsuit. The deal was reached to end an infringement lawsuit that was filed over the same ads before Drugstore.com's acquisition of Vision Direct in 2003.

Drugstore.com, based in Bellevue, Wash., is an online retailer of health and pharmacy products.