visual function

Question 1

eye follow

Answer 1

smoothly and continually (no saccadic beats) follow stimulus (at 30˚ per sec) with both eyes in all directions

Question 2

eye follow process for all

Answer 2

visual input detected by photoreceptors > visual cortex (occipital lobe) for processing and interpretation
* cranial nerves: oculomotor, trochlear and abducens must be working for smooth eye follow in visual fields

Question 3

eye follow timeline

Answer 3

4 weeks: eye follow horizontal stimulus
6 weeks: eye follow vertical stimulus
12 months: eye follow in all directions
6 years: head/eye dissociation with eye follow

Question 4

atypical EF response

Answer 4

• can’t follow in all visual fields
• adverse signs of rubbing eyes, blinking reddening
• inconsistent/jerky follow
• abnormal eye mvmt

Question 5

fast follow

Answer 5

ability to visually keep contact with a fast moving stimulus (with both eyes) in horizontal, vertical and diagonal directions

Question 6

fast follow performance

Answer 6

12 months: good fast follow of stimulus, slight overshoot/undershoot normal
3yrs: more refined strategy and less overshoot/undershoot for fast follow

Question 7

Fixation and release (sheet off paper hiding)

Answer 7

ability to fixate and release gaze from visual stimulus using binocular and monocular vision

Question 8

fixation and release timeline

Answer 8

emergence: by 4yrs - fixate gaze on object for 3 secs then release gaze to look at another
4+ = can complete with monocular vision

Question 9

atypical fixation and release response

Answer 9

• can’t follow in all visual fields
• adverse signs of rubbing eyes, blinking reddening
• abnormal eye mvmt
• eyes get ‘stuck’ or ‘lost’
• child needs to pull head away to release gaze

Question 10

convergence and divergence

Answer 10

ability to smoothly follow a slow visual stimulus with both eyes equally when moving from a distance towards the face

Question 11

convergence and divergence timeline

Answer 11

emerges: from 12 months = good convergence/divergence when following a stimulus 1m to 10c, from face
progression: 12+ = symmetrical follow with both eyes when on eye covered

Question 12

atypical convergence and divergence timeline

Answer 12

• can’t follow in all visual fields
• adverse signs of rubbing eyes, blinking reddening
• abnormal eye mvmt
• asymmetry or lack of mvmt of either eye
• asymmetry may sjow dysfunction or tightening of the ocular muscles, preventing mvmt in a particular direction
• Strabismus convergent (bilateral squint ) = abnormal axis of eyes relative to eachother

Question 13

Optokinetic nystagmus

Answer 13

induce visual nystagmus, symmetrically in both directions when looking at each alternating stripes moving slowly across the visual field

Question 14

optokinetic nystagmus stimulus

Answer 14

reflex visual nystagmus stimulated via visual input of alternating and symmetrical objects. IMPORTANT FOR EYE MVMTS SEEN IN READING

• present at birth and remains throughout life

Question 15

Optokinetic nystagmus atypical response

Answer 15

• absence of reflex
• only elicited in one direction
• abnormal eye mvmt
• loss of balance or dizziness
• asymmetrical btwn eyes
• inconsistent or variable response

Question 16

fast follow atypical

Answer 16

• can’t follow in all visual fields
• adverse signs of rubbing eyes, blinking reddening
• abnormal eye mvmt
• inconsistent/jerky follow
• excessive overshoot/undershoot

Question 17

eye follow problem indications

Answer 17

may indicate brainstem dysfunction, poor VOR control, cranial nerve function therefore requires further assessment