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78 Cards in this Set
- Front
- Back
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6 Cardinal positions of gaze
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Up & right (RSR & LIO)
Right (RLR &LMR) Down & right (RIR & LSO) Up & left (RIO &LSR) Left (RMR &LLR) Down & Left (RSO &LIR) |
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Duction
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testing only one eye
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Versions
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testing both eyes against each other
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When to test ductions
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only if versions are abnormal
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Primary position of gaze
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eyes straight ahead
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secondary position of gaze
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right, left, up, down
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tertiary position of gaze
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up and right
down and right up and left down and left |
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Herring's Law
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EOM contracts, the same nerve stimulation occurs to the muscle's yoke muscle in the contralateral eye.....
causing both eyes to move in the same direction |
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Sherrington's Law
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as a muscle is stimulated to contract, it's antagonist muscle in the same eye is relaxed
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CN III
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SR
MR IR IO |
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CN IV
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SO
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CN VI
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LR
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Strabismus
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misalighnment of the eyes. Prevents stereopsis, may lead to amblyopia.
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Complaint of diplopia
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usually means development of problem after childhood (because children can suppress)
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Medial Rectus
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Adduction
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Lateral Rectus
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Abduction
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Superior Rectus
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Elevation, Intorsion
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Inferior Rectus
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Depression, Extorsion
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Superior Oblique
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Intorsion, Depression
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Inferior Oblique
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Extorsion, Elevation
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Fusion
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Ability of eyes to lock onto an object, enabling them to align together to keep the image on each fovea simultaneously
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Phoria
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strabismus demonstrated when fusion is disrupted, latent
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Tropia
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a constant eye turn , manifest
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Orthophoria
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proper eye alignment
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Stereopsis
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ability to perceive depth in 3D
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Suppression
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the brain ignoring the image from one eye
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Amblyopia
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lazy eye, loss of vision without any apparent disease of the eye
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Nystagmus
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involuntary rhythmic bilateral oscillation of eyes
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Saccades
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fast eye movement usually seen during refixation, can be voluntary or reflex (rapid eye movement in sleep)
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3 principal properties of the visual system
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Eye motility
eye alignment fusion |
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the cover/uncover portion of the test will reveal
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tropia
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the alt cover test will reveal
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phoria
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stereopsis is measured in
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minutes, or seconds, of the arc
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Hirschberg test
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displacement of corneal light reflex to estimate amount of deviation
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every 1mm of deviation in the hirschberg test is equal to
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15 prism D
or 7 Degrees |
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Krimsky's test
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using a prism to match up the corneal light reflex
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Concomitant Deviations
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amt of deviation is the same in all positions of gaze (typically childhood only)
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Incomitant deviation
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amt of deviation veries in different positions of gaze (typically are neurogenic or restrictive in nature)
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Titmus test
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uses polarized glasses and a book with polarized images to measure a patient's stereopsis
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Worth 4 dot test
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uses glasses with red and green lens and a flashlight with 4 dots in the lens cover
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Infantile esotropia or exotropia, noted at birth
accomadative esotropia developes by age 2 in high hyperopes sensory strabismus |
concomitant deviation
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Cranial Nerve palsy (3, 4, 6)
Congenital restrictive problems overacting obliques |
Incomitant deviations
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6th nerve palsy
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complains of horizontal diplopia that worsens when looking towards the side of palsy
frequent in diabetics and hypertensive patients will resolve in time |
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4th nerve palsy
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complains of vertical or skewed vertical diplopia, worse in down gaze
commonly seen in diabetics and hypertensive patients head trawma often will resolve in time |
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3rd nerve palsy
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less common
will complain of eyelid being droop and if elevated will have skewed diplopia if pupil is involved (dilated on side of palsy) concern is high for an aneurysm |
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Maddox rod test
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If there is a phoria the streak of light will not intersect the spot of light. The amount and type of the phoria can be quantified by placing a prism of appropriate power and direction in front of either eye such that the streak appears superimposed on the spot of light
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Corneal light reflex testing
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rudimentary strabismus test. Don't provide as much info as cover testing, but are easier to use and require less cooperation by the patient.
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temporal light reflex displacement on one pupil
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esodeviation
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nasal light reflex displacement
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exodeviation
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what can complicate the light reflex test
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misshapen pupils and abnormal retinal architecture
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after age 6 & 7
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vision and ocular motor control become difficult to change
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normal vision is achieved after _____ of age
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6mo
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pseudostrabismus
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child who may appear to have an ocular deviation but has no detectable strabismus
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the apex of the prism is placed
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in the direction of the eye turn
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the lees screen test
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is not as dissociating a test because there are no red/green glasses
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hess lancaster screen test
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patient wears red/green goggles, tries to place a light from a flashlight over the examiners flashlight light
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normal retinal correspondence
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images from the fovea of the two eyes project in the same visual direction
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anomalous retinal correspondence
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faulty sensory adaptation to strabismus, the fovea of one eye projects tot he same point in space as an extrafoveal point on the retina of the other eye (not in the same direction)
develops mostly in long standing monocular strabismus |
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with the afterimage test the patient with have displaced bars if
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the patient has ARC
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Major amblyoscope
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instrument with two view tubes, in which two slightly different images are placed. Tests Grade 1, 2, and 3 binocular vision
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Grade 1 binocular vision
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requires simultaneous perception
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Grade 2 binocular vision
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requires fusional ability
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Grade 3 binocular vision
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requires coordinated use of the two eyes together to provide the sensation of stereopsis
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Cover/uncover test tests for ________
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tropia (manifest)
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alt cover test tests for ______
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phoria (latent)
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why does the alt cover test work?
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breaks fusion
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what line of the snellen chart do patients read while doing the cover tests
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line bigger than their corrected vision
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If versions are normal then
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there is no need to test ductions
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Worth 4 dot test results 2 dots in the _____ eye
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left
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Worth 4 dot test results 3 dots in the _____ eye
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right
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Worth 4 dot test, If patient sees 4 dots they have
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fusion
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Worth 4 dot test, If patient sees 5 dots they have
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diplopia
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The purpose of version testing in the 6 cardinal positions of gaze is to
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evaluation of the underaction and overaction of eye muscles
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tropia is best differentiated from a phoria by
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cover/uncover test
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on cover/uncover testing, a phoria is present if
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the covered eye moves immediately after the cover is removed
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the test used to quantify deviations in patients who can fixate easily is
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alternate prism/cover test
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the test most useful for identifying a small angle tropia when a larger phoria is present is
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cover/uncover test
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the test used for patients who are unable to fixate or cooperate is
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hirschberg test
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