Deficits Flashcards
Pupil structure
Controls the amount of light that enters the eye
The muscles that control pupil size are different than the muscles that control lens shape
Lens structure
Helps us sharpen focus during visual tasks
Lens shape is controlled by the cillary muscle
Retina structure
Where the cones and rods are
Allows us to view/perceive visual information, which then sends to the brain via optic nerve
PERRLA
Pupils equal, round and reactive to light and accommodation
Pupillary light reflex
Shine a light into the side of someones eye (directly is too uncomfortable)
The eye that has direct light stimulation will constrict (pupillary light reflex), and the opposite pupil, which is unaffected directly by the light, will also constrict (consensual pupillary light reflex)
Eye accommodation
The eyes ability to focus on objects both near and far away
Muscles within the eye work to cause the lens of the eye to become rounder (near vision) or flatter (far vision)
Convergence
Ability of your eyes to come together to keep an object in focus
Cause of double vision
With bi-ocular vision, it can be the eyes not working together
With monocular vision, it can indicate that they may have an impairment within the eye (such as retinal detachment)
Smooth pursuit eye tracking
The H test test
Common deficits include nystagmus, saccadic jumps within the smooth pursuit, and symptom provocation
Nystagmus
Abnormal eye movement where the eye quickly beats in one direction and slowly returns to its current start point
Saccades
A naturally occuring eye movement where the eye jumps from one fixation point to the next
However, can occur abnormally during eye tracking
All saccadic movements are relatively the same speed
Saccade testing
Looking from one object to another in horizontal and vertical planes
Saccadic dysmetria
An over or under shoot of the eyes when moving to look at a target
Skew deviation
Vertical misalignment of the eyes due to improper neuromuscular function
Testing skew deviation
Focus on an object infront of them, and while they focus, cover each eye one at a time. If skew deviation is present, the eyes will shift up or down to focus on the object
Sense angular acceleration
The 3 semicircular canals
Sense linear acceleration - horizontal
Utricle
Sense linear acceleration - vertical
Saccule
Houses the crista
Ampulla
Houses the cupula and hair cells
Crista
Cupula
Structure that surrounds the hair cells/bundles
Hair cells/bundles movement
Causes a change in polarization of the structure it is associated with
Otolithic membrane
Structure that encapsulates and shifts the hair cells in response to the effect of linear motion on the otoconia
Otoconia
Calcium carbonate crystal that sits on top of the otolithic membrane
Kinocillum
The longest hair cell (aka the parent)
Stereocilia
The other, shorter hair cells of the cell bundle
Benign
Not damaging, although very uncomfortable
Peroxysmal
Sudden onset, does not last long
Positional
Only occurs in a certain position/movement
Vertigo
Feeling of the world around you spinning
Dizziness
Feeling faint and unsteady (not the same as vertigo)
Benign peroxysmal positional vertigo (BPPV)
Occurs when an otoconia crystal from one of the otolithic organs is knocked loose and falls into one of the semicircular canals
Changes how fluid movement in the semicircular canal is perceived by the hair cells and causes altered movement sensation (vertigo)
Posterior canal BPPV is detected by
Dix-hallpike maneuver
Vestibulo-ocular reflex (VOR)
A gaze stabilizing reflex that utilizes sensory signals from the vestibular system to create compensatory eye adjustments
Head impulse test
Holding either side of the head, lightly rotate the head side to side then quickly move head back to midline. The patients VOR should allow them to maintain their eyes looking at the visual target
Cervico-ocular reflex
Movement of the neck results in compensatory eye movement
Proprioceptors in the next provide feedback to initiate eye movement
Optokinetic reflex
Head reamins stationary, but the eyes move to follow an object (sitting in a car watching individual telephone pass by without moving your head)
Balance error scoring system
Hands on hips, eyes closed for 20 seconds, shoes removed
Each stand is done first on solid ground then on a foam pad
- Double leg stance
- Tandem stance
- Single leg stance (non-dominant leg)
Balance error scoring system errors
Remove hands from hips
Opening eyes
Step/stumble
Lifting forefoot or heel from testing surface
Hip flexion/abduction beyond 30 degrees
Stay out of test position for >5 seconds
Balance Error Scoring System score
0-60 and represents the number of errors in each test position
Lower score is better
Can have max number of errors as 10 per stance position
