Vision for Function PDF Presentation

Presente d by Lois Vision for Function Stevens  Visual Examination Typically vision is assessed by the medical team as part of the cranial nerve examination.  Visual Acuity Visual acuity is the measure of the ability of the eye to distinguish shapes and th...

Presente d by Lois Vision for Function Stevens  Visual Examination Typically vision is assessed by the medical team as part of the cranial nerve examination.  Visual Acuity Visual acuity is the measure of the ability of the eye to distinguish shapes and the details of objects at a given distance. It is assessed by an optometrist using a Snellen chart.  Physiotherapy There are aspects of vision which are simple and relevant for physiotherapists working in the field of neurological rehabilitation to assess: Visual field Fixing Scanning  Visual Field The visual field refers to the total area in which objects can be seen in the side (peripheral) vision as you focus your eyes on a central point. A normal visual field measures 90 degrees temporally (laterally), 50 degrees nasally (medially) 50 degrees superiorly, and 60 degrees inferiorly. Visual acuity increases from movement discrimination in the extreme peripheral vision to better than 20/20 in the centre of vision  Why? Input from visual fields is important to get a complete picture of the external environment and therefore is needed for safe and effective navigation e.g. getting around one’s home, the shops or neighbourhood. A lesion here may hinder functional ability.  Fixing and Scanning Visual acuity requires coordination between head and body movements to ensure that visual stimuli are directed to the appropriate part of the retina. This is achieved by Fixing and Scanning.  Visual Fixing Visual fixation is the orientation of the eyes so that the image of a viewed object falls on the central part of the retina. Inability to maintain a fixed gaze may indicate a deficient vestibulo-ocular reflex (VOR) This may implicate the vestibular system or cranial nerves lll or lV.  Visual Scanning Visual scanning is the movement of the eyes from point A to point B. It allows the individual to search in a systematic manner such as top to bottom and right to left, thus identifying information relevant to the environment. Inability to scan through range might indicate a problem with cranial nerves lll, lV or Vl.  Why do we need to know about this? A deficit affecting fixing and or scanning may result in poor balance and inaccurate movement for function. It is estimated that up to 40% of people following stroke will have a visual defect. It is estimated that up to 50% of people following a traumatic brain injury will have a visual defect. Cranial Nerves Eye muscles  Cranial Nerves Cranial Name Sensor Functio Nerve y or n/ Motor Muscle s Activat ed ll Optic Sensory Vision lll Oculomot Motor All or extrinsic eye muscles except SO and LR (see below) lV Trochlea Motor Superior  Visual Pathway For interest only! Right Homonymous Hemianopia  Right Homonymous Hemianopia (HH) The most common location of lesions resulting in HH is the occipital lobe , followed by damage to the optic radiations. The remainder is caused by lesions of the optic tract , lateral geniculate nucleus (LGN) , or a combination of several areas.  Depth Perception Depth perception is the ability to see things in three dimensions (including length, width and depth), and to judge how far away an object is. For accurate depth perception, you generally need to have binocular (two-eyed) vision. Jeepers, creepers, where’d you get those peepers?