Sensory integration (part 2) – The Visual System
THE ANATOMICAL REVIEW – REGISTRATION
Lights enters the eye and is refracted by the cornea. The light then passes through the pupil and is further refracted by the lens. An inverted image is then projected onto the retina. The retina consists of rods and cones – called photoreceptor cells. Rods are found in the periphery of the retina and process low levels of light. Cones are found in the centre of the retina and process colour. The rods and cones send impulses to the bipolar cells onto the ganglion cells. There are 4 different types of ganglion cells that send visual information to the brain.
The optic nerves from both eyes meet and cross at the optic chiasm (at the base of the hypothalamus).
THE VISUAL SYSTEM AND SENSORY INTEGRATION
Types of modulation difficulties: over-responsive and under-responsiveness.
The following lists are a combination of Lombard (Lombard, 2007, p. 59), (Australia, SPD Australia, 2013) and Sensory Processing Disorder (www.sensory-processing-disorder.com):
o Feels confused by too many visual information (cannot focus on reading/writing/table top tasks for
o Gets easily distracted by other visual input
o Bothered by fluorescent / bright lights e.g. watching TV (will rub eyes/watery eyes/headaches)
o Enjoys playing in a darkened room
o Feels confused in places with a lot of people / activities
o Bothered by quick moving visual images on TV
o Avoids eye contact
o Doesn’t always observe when someone enters/leaves a room
o Doesn’t see fine detail
o Cannot find objects that are stacked on-top of each other
o Gets lost easily, even in familiar surroundings
o Will stare without being aware of it
Sensory craving behaviour
o Likes flashing lights
o Watches spinning objects
o Prefers TV/video games
o Difficult to build puzzles/cutting/sorting
If you child exhibits these symptoms and it is influencing his/her daily functioning at school, home and socialization, please contact an occupational therapist.
The book ‘The out of sync child has fun’ by Kranowitz is a lovely book to explain modulation difficulties and gives loads of activities that can be done at home to improve this. But don’t try to manage this by yourself, contact your local occupational therapist for guidance.