The Visual system Maude LeRoux Sofia, Bulgaria May 2012 Definition and clinical analysis of ocular motor skills The Visual system

The Visual System Vision is the ability to see and process visual details in our environment. It is closely related to the other sensory systems of auditory and vestibular. Vision plays a major role in our ability to adapt to our environment (Zoltan, 1996). Visual perception is our mechanism for interpreting input around us; it includes figure-ground, memory, spatial relations, discrimination, and closure.

Visual Development Vision matures outside of the womb, color first in black and white, then spectrum of colors between 400 and 700 nanometer. Mostly 3D vision during creeping and crawling phase, important for motor development and depth perception for movement Some children develop misperceptions of the 2D symbols of reading when not being able to transition easily from 3D to 2D

What can go wrong with the visual? Motor Orthographic General Vision Transient Saccades Fixation Contrast Sensitivity Peripheral Sequential positioning Persistence Retention Acuity Image stability

Visual System Visual Acuity Visual Perception – Figure-Ground, Discrimination, Closure, etc. Visual – Spatial Ocular Motor Skills – Pursuits, Saccades, Convergence / Divergence Eye-hand coordination Visual – Motor skills

Ocular Motor Skills: What to consider Does the client become uncomfortable in his/ her chair? Is the client able to maintain a still upright posture? Does the client attempt to hold his/ her head while performing these activities? Does the client’s eyes become red or tear? Does s/he blink often? Does the client attempt to move his/ her head while performing these activities?

The Visual System: Clinical Observations Ocular Motor Skills: physical structure of the six extraocular muscles around the eye; the ability to enable both eyes to work together at a similar speed Visual Pursuits: smooth tracking movement of the eyes (i.e. used in watching a ball move) Saccades: ability of the eyes to shift rapidly from one position to another (i.e. used in reading)

Ocular motor skills: Visual Pursuits Hold a pen or pencil in front of the client, between 12 and 24 inches from the nose Slowly move the target object in horizontal, vertical, diagonal, and circular motions Watch for jerky movements, especially across midline (at the nose). Does the client lose the target?

Ocular Motor Skills: Visual Saccades Hold two objects between 12 and 24 inches from the nose at either side of the visual field (right and left). Have the client shift his/ her gaze from one object to another in a smooth and controlled manner. Look for inaccurate visual targeting: either over-shooting or under-shooting the target.

Activities that Develop Visual Perception Forms & Shapes Catching, trapping, and striking Throwing Locate Objects in space