Sensory Processing is the ability to take in information through the senses of touch, movement, smell, taste, vision and hearing, and combine the resulting perception with prior information, memories, and knowledge already stored in the brain.
In order to derive coherent meaning from processing stimuli, the mid-brain and brain stem regions of the central nervous system are early centers in the processing pathway for sensory integration.
This is not the same as blindness or visual acuity problems that are caused by the sensory organ being defective, unlike those disorders, sensory information is sensed by people with SPD, but the information tends to be analyzed by the brain in an unusual way that may cause pain or confusion.