Semantic-Pragmatic Disorder may be a variant PDD or it may be just a descriptive term for the language impairment in autistic spectrum disorders. Irlen lenses are thought to reduce light sensitivity and perceptual distortions. The timing of how the information is received by the brain is theoretically also changed which allows correct interpretation of visual stimuli. I did a quick web search for people wanting info on Irlen Lenses. Helen Irlen developed the Irlen method which is predicated on the belief that certain cells in the retina are over-stimulated and send incorrect signals to the brain.
Symptoms can include blurring of print, double vision, movement of print, eyestrain, etc.
Donna Williams, autistic individual and author of Nobody Nowhere and Somebody Somewhere, writes about its results. The method starts with placing colored overlays over printed pages which are later replaced with colored lenses. These are thought to reduce light sensitivity and perceptual distortions. The timing of how the information is received by the brain is theoretically also changed which allows correct interpretation of visual stimuli. Thought to be a problem in how the visual cortex processes information, it is said to cause visual problems, hypersensitivity to light and difficulties with depth perception.