In an on-going study of visual characteristics of personnel diagnosed with a mild traumatic brain injury (MTBI) related to their service in Iraq and Afghanistan we found a high rate of binocular vision problems (such as double/blurry vision, reading difficult, etc.). These individuals are also usually diagnosed with post traumatic stress disorder (PTSD). PTSD is known to cause some vision symptoms. We wish to conduct this study on individuals with PTSD (but not an MTBI) to see if they have symptoms similar to those in individuals who have MTBI. This will provide us with information useful in determining the specific cause of the visual symptoms in the MTBI population.