Many patients with PTSD feel overwhelmed in situations with high levels of sensory input, such as in crowded situations with complex sensory characteristics. These difficulties might be related to subtle sensory processing deficits  such as those found in individuals with Visual Stress, a neurological sensory processing difficulty triggered by patterns, contrast and movement. The result is a hyperactivation of the visual cortex leading to symptoms that include headaches, sensitivity to light and perceptual distortions in the environment.
Complicating the diagnosis of PTSD is some overlap with patients with traumatic brain injury (TBI). The estimated range of patients with TBI having PTSD varies from 17% to 40%. As a result of the sensory vision system's interconnections with the structures of the limbic system, blurry vision is a common symptom in PTSD patients. 
Studies have shown the effectiveness of individually prescribed precision coloured filter lenses in relieving visual perceptual symptoms related to acquired brain injury. Visual Stress should be investigated to determine if it is contributing to symptoms and precision coloured filter lenses should be investigated as a potential tool to help manage symptoms of PTSD.
For more information, please refer to the anxiety and the post-concussion/acquired brain injury sections.