After heading up the Perkins School for the Blind for 11 years, Steven M. Rothstein announced Tuesday that he would be leaving his position as president next year. Rothstein did not specify in his announcement, which was posted on the school’s website, what his next professional endeavor would be. Rothstein said he will stay on as president through Dec. 31, and might remain through the end of the academic year next spring, while the school’s board of trustees begins a national search for a successor. During his tenure as the ninth president at Perkins, Rothstein has expanded the school’s services globally and online, increasing its reach from 40,000 to more than 700,000 people, said Frederic M. Clifford, the board’s chairman, in a statement on his departure. In addition to raising awareness and serving as an advocate for Perkins, which serves students with visual and hearing impairments, Rothstein has also helped lead the renovation and expansion of its North Beacon Street campus; ramped up the school’s technology efforts; and helped raise $130 million in a capital campaign, according to Perkins officials. A Williams College graduate who also holds a master’s degree from Northeastern University, Rothstein previously served as assistant commissioner of the state’s Department of Mental Retardation, and has sat on the state’s Board of Education. He also helped cofound Citizens Energy Corporation, a nonprofit that provides tens of millions of dollars in energy and medical benefits to low-income citizens, both in the United States and abroad.