"It happened so quickly," said Daniel Casara, whose first tour of duty in Iraq in 2005 only lasted three weeks because it was cut short by a bomb hidden in the road.
"The explosion itself, it's almost like a car accident that you don't see," Casara told ABC7 Chicago.
The blast flipped his vehicle, killing two of his fellow soldiers and crushing his legs. But Casara says some of his and his fellow soldiers' deepest wounds were hidden from view.
"These are images that you just can't get out of your head," he said.
Casara says he suffered from post traumatic stress disorder, or PTSD. He also says he had trouble sleeping and was anxious and flustered after the attack.
He is not alone. Some studies say 20 percent of veterans returning from Iraq and Afghanistan are suffering from PTSD.
"They think it's just normal, and they're just doing the best they can," said Michael Gremley, a Chicago entrepreneur who created Voiceprism, a system that he hopes can help change the way the military screens for PTSD.
"There's a stigma with psychological exams and PTSD in the military. So, the soldiers, they want to stay with their buddies and what they end up doing is saying, 'I don't have bad memories. I'm doing fine,'" Gremley said.
Instead of the current written questionnaire, Gremley's program tests soldiers for PTSD by analyzing stress levels in their voices.
A visual reading of the color red from the test means that stress levels are above a certain level.
Soldiers are asked questions about things they experienced during their deployment. Then, their answers are recorded and analyzed for stress.
"When we're experiencing stress we speak differently than when we're relaxed," Dr. Paul Larson said.
Larson, of the Chicago School of Professional Psychology, is one of Voiceprism's advisors. He specializes in helping veterans cope with stress.
"They can't help but speak in a certain way if they are experiencing certain emotional states," said Larson. "It just leaks out."
Voiceprism is also testing their technology by measuring stress levels of nurses at the Cleveland clinic and checking veterans for PTSD with the Vietnam Veterans of America.
"The battle for a lot of people isn't over when they come back," said Justin Savage.
Chicago-based Web site www.VetsPrevail.com is creating an online network to increase access to mental health care.
"It's really tough for a culture of warriors, of people who have stood up and proudly fought and defended our rights, for those people to say, 'Hey, I need a second. I need to take care of me,'" Savage said.
Daniel Casara's Army memories cover the walls of his home. He says looking at his accomplishments helps motivate him to keep getting better.
"Everybody has their own way of dealing with things, and you just hope that there's something that helps these individuals get through what they're going through," said Casara.
Casara also keeps challenging himself physically. He has gone skydiving and completed the Chicago Marathon on a hand-pedaled bike this year. He has also run up the Willis Tower. His next challenge is to try out for the U.S. Paralympic volleyball team.
For more information about help for veterans struggling with stress, visit: