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Steven Senne, Associated Press
In this Wednesday, April 8, 2015 photo, Boston Marathon bombing survivor Lynn Crisci, of Boston, front, listens during a Massachusetts Resiliency Center meeting at the Old South Church, in Boston. Crisci, who was near an explosion at the finish line of the 2013 Boston Marathon, has suffered from hearing loss, traumatic brain injury, and post-traumatic stress disorder.

BOSTON — Survivors of the 2013 Boston Marathon bombings have been slow to take advantage of programs meant to help them cope with what experts call "invisible injuries."

Just a portion of 240 qualifying survivors have participated in services offered through the One Fund Center, which was launched in September to address anxiety, stress and other unseen wounds including eyesight and hearing problems.

The Massachusetts Resiliency Center has been offering behavioral health services to the scores of people affected by the attacks — regardless if they were physically hurt or not.

But it says it's only seen a few hundred people since it opened last October.

Although the centers have funding for at least two years, organizers say it may be years before many understand the emotional toll and decide to seek help.