Optoprep accom, vergence Flashcards
Sjorgen Disease
Dry eye , Dry mouth , arthritis
what is Troxler’s effect
When one fixates at point after 20 seconds the peripheral will fade away
What is Version ? what it is purpose ?
BINOcular eye mov. both eye in the same direction . (conjugate)to enlarge the field of view
What is vergences ?
both eye to obtain binocular fixation and fusion , eye moves in OPPOSITE direction ? ( disconjugate)
what is the function of all superior? what is the function of all Obliques ?
INTORT
AB duct
what is the primary function of Obliques ?
INtort and Extort
Superior Rectus ?
innervate by CN3 , ( elevation , intort, ADDuct)
Insert on the top of the anterior to the equator and 23 DEGREE temporal to the line of sight
inferior rectus ?
innervate by CN3 , insert on the bottom of the anterior to the equator and 23 Degree temporal to the line of sight ( depression, Extrot , ADDuct .
Superior Oblique ?
SO4–> CN4 Angle 54 DEGREE ( intort , depression, ABduct )
Inferior Oblique?
CN3 , Angle 51 DEGREE ( Extrot , elevation, ABDuct)
what is the spiral of Tillaux ?
Describe the line of insertion of recti muscle ( MILS ) Medial Rectus ( closest to limbus)> Inferior Rectus >Lateral>sR
Hering’s Law ?
2 EYES , ( Yoked Muscles )two eyes must receive equal innervation . one from each EYE
(LR , MR), (SR, IO), (SO, IR )
Sherrington’s Law ?
SAME EYE , one muscle excited and another relax , ( SR,IR),( IO,SO), (LR,MR)
Fixation sys?
VOR vestibular sys ?
OKN Optokinetic ?
Fixation–> hold image while head is motionless
VOR–>hold image while short motion of head
OKN–>hold image while prolong head mov.
what movement is the fastest ? slowest?
lonngest and shortest latency
SAccades is the fastest , Slowest is the vergence
shortest latency VOR , longest latency Saccades
different between OScillopsia Vs Vertigo ?
sensation of objects moving up and down
Vertigo-> sensation of body movement
Caloric Test ?
head to one side and water in the inner ear.
Normal –> warm water R ear
–>slow conjugate move to L and
–> fast Movement back to the right ( Nystagmu)
COWS = COLD opposite (Nystagmus
Warm–> Same direction (Nystagmus
what you use for Nystagmus ?
BO or (-) lens because converg. decrease Nystagmus
what conditions could lead to Nystagmus ?
Aniridia , Albinism, achromatopsia,
Pathological Nystagmus Vs physiological ?
Pathological –> associate with ocular motor abnormality ,
Different from Optokinetic reflex Vs Optokinetic nystagmus ?
Optokinetic reflex –>hold image on fovea while prolong head Movement (>30 sec)
Optokinetic nystagmus–> Maintain the image of MOVING object on the fovea when the head is still
When the OKN developed ?
3-4 months after birth , and cortical region is responsible for it
Saccades ?
fastest velocity and longest latency, voluntary but sometimes is involuntary
what is the most common saccadic error?
undershooting
what is in responsible of Saccades ? (IMPortant)
COntralateral frontal eye field
and ocuuipitoparietal junction
what happen is damage in the right frontal eye field ?
impaired saccades toward the left
eye turning to the right
( saccade to Opposite ) side of lesion
eye turn to the SAME side of lesion
Damage in superior colliculus?
change in velocity and accuracy od saccades
saccades suppression
to prevent blurry image duringsaccade vison is suppresed by cortex
Pursuit ?
Saccades?
smooth , slow tracing movement that allow fixation of the fovea on a moving object.
Saccades–> rapid yoked movement move the fovea to an object of interest in the visual field
what is the threshold that eye has pursuit ? right before saccades kicks in ?
> 50 degree / seconds –>saccades
Pursuit controlled by ?
Parietal lobe to the IPSilateral side
Tonic vergence ? Proximal ? Fusinal ?
Tonic vergence–>eye position at rest at distance without stimulus to conv or accom
Proximal conv–> person aware of near target
fusional –> initiated by retinal image disparity and helps the eye compensate for a phoria to obtain bifoveal fixation and binocular vision
( Motor fusion )
decompensating phoria ?
large phoria pt used to compensate for it but now it is hardand result in tropia and symptoms of diplopia
NON comitant Vs Comitant ?
NOn comitant –> caused by EOM ( misalignment not the same for all gazes )
Comitant –> decompensating phoria
SO problem PT will
hyper deviation increase ADduct and depression of affected eye
Head TIlt ?
SO–> head tilt AWAY from the lesion side
IO –> head tilt TOWARDS to the lesion side
Forced Duction test for Comitancy ?
Positive –> muscle restriction –>eye DOES NOT MOve
Negative–> EYe moves ( Muscle Palsy)
Duane’s syndrom
congenital left eye in F,
Type I –> Limites ABduct ( CN6 palsy) most common)
Type II–> Limit AD duct ( leastcommon )
Type III–> Limit AB duct + ADduct
Brown’s syndrome ?
Involved SO muscle and tendon abnormality of
trochlea ,
Mr Brown gets DOWN ( HYPOtropia ) in primary gaze and limited elevation during ADduct
Parks 3 step
which eye highest hyper deviation ?
is the hyper worse when he looks R or L ?
hyper worse when person tilt her head L or R?
R eye
right side
right head tilt ?
1- right eye ( circle the bottom right )
2- right side ( circle my left side)
3- head tilt to R ( circle diagnale to my left )
answer is LIO
which eye is only intential and conjugate
microsaccades
A +3.00 D hyperope is corrected with a +1.50 D contact lens bilaterally. If he views a near object located at 22.0 cm, what degree of accommodation is required to achieve a clear retinal image (rounded to the nearest 0.25 D)?
+6.00 D
+7.50 D
+1.50 D
+4.50 D
+6.00 D
target require 1/0.22=4.5D
and Pt hyper 3D need 3D to accomed but he is corrected by 1.5
now he has 1.5 hypweropia ( need to accom)
1.5 +4.5 = 6 D
While performing the alternating cover test, with the left eye covered, the right eye behind the occluder assumes an exo position. If the right eye were to maintain an exo position when the occluder is removed where would the target’s image fall on the retina in relation to the fovea?
The target’s image would be superior to the fovea
The target’s image would be nasal to the fovea
The target’s image would be inferior to the fovea
The target’s image would be temporal to the fovea
The target’s image would be temporal to the fovea
An exo position places the fovea of the right eye nasal to the image projected from the object of regard. This is due to the outward rotation of the eye which rotates the fovea nasally relative to the object. This places the target’s image temporal to the fovea.
A patient is seen at your office reporting horizontal diplopia that is worse towards the end of the day. Unilateral cover testing reveals no movement of either eye. Which of the following can correctly be concluded from the above findings?
The patient does not likely possess a heterotropia or a heterophoria
Further testing is required prior to reaching a conclusion regarding the presence of an ocular deviation
The patient does not likely possess a heterophoria
The patient does not likely possess a heterotropia
The patient does not likely possess a heterotropia
he unilateral cover test (UCT) is useful in diagnosing a heterotropia. If a person does not suffer from a heterotropia, then no movement would be observed on the UCT. A heterophoria would present only on the alternating cover test (ACT).
Convergence of the eyes occurs with which of the following?
Extortion of one eye and intorsion of the other
Intortion of both eyes
Adduction of one eye and abduction of the other
Abduction of both eyes
Adduction of both eyes
Adduction of both eyes
In vergence movements, the eyes move in opposite directions. In convergence, both eyes adduct (move medially). In divergence, both eyes abduct (move laterally). Intortion of both eyes is known as incyclovergence. If the left eye abducts and the right eye adducts, both eyes are moving to the patient’s left; this is called levoversion. If the right eye abducts and the left eye adducts, both eyes are moving right and this is called dextroversion.
Which of the four involuntary vergence stimuli is driven by neural innervation?
Tonic
Fusional
Accommodative
Proximal
Tonic
Tonic vergence is caused by baseline innervation. This type of vergence is generally maintained when all other vergence stimuli are absent. Proximal stimuli are driven by near objects. The response increases as the distance from the object decreases. Accommodative response results from target defocus. Fusional involuntary vergence is provoked by retinal disparity.
You are able to accurately screen for a heterophoria by performing a cover test on your 4 year-old patient. To properly complete this examination, which of the following tests does NOT need to be performed?
Color vision testing
Stereoacuity
Hirschberg testing
Determining the near point of convergence
Monocular estimate method (MEM)
Hirschberg testing
Hirschberg testing and cover testing are both utilized to denote the presence of an ocular deviation; therefore, Hirschberg testing does not need to be performed on this patient.
22 year-old male presents with a history of a right orbital medial wall fracture and restriction in right gaze on extraocular muscle testing. Which of the following additional tests is MOST useful in determining whether the limitation is secondary to muscle entrapment or muscle paralysis?
Electrooculogram
Forced duction testing
X-ray imaging
Exophthalmometry
Cover test
Visual evoked potential
Forced duction testing
Forced duction testing is an in-office procedure that is used in differentiating between muscle weakness and restrictive causes of limitations in extraocular muscle movements. This test is typically performed when a patient is anesthetized using topical eye drops. The patient is then instructed to look as far as possible in the direction of the muscle that is suspected of underacting such that maximum innervation is recruited to that muscle. The examiner will then use forceps in order to grasp the conjunctiva as close to the area of the limbus as possible, opposite the side of gaze restriction. If the forceps can then rotate the globe further than where the patient can move it on his own, some degree of muscle paresis is likely. However, if the globe cannot be rotated farther, restriction or entrapment of the muscle is probable. For example, if the patient has a deficit in superior gaze, the insertion of the inferior rectus muscle should be topically anesthetized. The patient’s gaze should then be directed upwards and the inferior rectus muscle should be grasped with forceps. Further superior rotation of the eye should then be attempted. Resistance is considered a positive forced duction test, while effortless rotation is deemed a negative forced duction test.
When determining the near point of convergence, which of the following sentences is TRUE?
As the object is moved closer, the accommodative system maintains the target clarity while the convergence system preserves fusion of the object
If diplopia is not reported by the patient, the test should be repeated until the patient reports blurring of the target
As the target is moved closer, diplopia is typically reported prior to blurring of the target
The maximal point of divergence is recorded in centimeters as the ‘break point’
As the object is moved closer, the accommodative system maintains the target clarity while the convergence system preserves fusion of the object
The near point of convergence (NPC) is the point in which the patient’s eyes are maximally converged. The NPC is determined by presenting the patient with an appropriate accommodative target at near and with the patient’s near correction in place, the patient is asked to keep the target clear and single. The target is then brought closer to the patient until either the patient reports that the image of the object appears double or the clinician notes that one of the patient’s eyes turns out. This point is measured and recorded from the spectacle plane in centimeters. While performing the NPC, the convergence system maintains fusion of the target and accommodation sustains clarity. Some patients may report blurring of the target (near point of accommodation) prior to experiencing diplopia, but rarely do patients report blurring of the target after experiencing diplopia. The majority of clinicians record ‘TTN’ or ‘to the nose’ for patients who do not report diplopia or do not exhibit a break in fusion.
Nerve fibers from the abducens nucleus innervate which of the following extraocular muscles?
Ipsilateral superior oblique
Contralateral superior oblique
Ipsilateral medial rectus
Ipsilateral lateral rectus
Contralateral lateral rectus
Contralateral medial rectus
CN6= Ipsilateral lateral rectus
CN4=The trochlear nucleus innervates the contralateral superior oblique muscle.
The nucleus of the abducens nerve (cranial nerve VI) is located in the dorsal lower portion of the pons. Motor neuron axons from the abducens nerve course from this location to the ipsilateral lateral rectus muscle via the cavernous sinus and superior orbital fissure. Additionally, interneurons also traverse from the abducens nucleus to the opposite medial longitudinal fasciculus (MLF) and terminate at the oculomotor nucleus, thus coordinating horizontal gaze movements of both eyes.
The oculomotor nucleus innervates the ipsilateral medial rectus, inferior rectus, and inferior oblique, as well as the contralateral superior rectus.
The vertical recti muscles are inserted in front of the equator, creating what angle with the visual axis?
23 degrees
67 degrees
19 degrees
51 degrees
39 degrees
23 degrees
The medial and lateral walls of the orbit are positioned at an angle of 45 degrees from each other. The orbital axis then forms an angle of 22.5 degrees with the medial and lateral walls (for the sake of simplicity, this angle is usually regarded as 23 degrees). Therefore, in primary gaze, the visual axis also forms an angle of 23 degrees with the orbital axis. The actions of all of the extraocular muscles depend on the position of the eye as each undergoes contraction. The vertical recti muscles run along the same line as the orbital axis, thereby also creating an angle of 23 degrees with the visual axis at their attachment point anterior to the equator. When the globe is abducted 23 degrees, the vertical recti muscles act purely to elevate or depress the eye.
In order to maintain binocular fixation and fusion on a target that is moved away from the patient in a linear fashion, assuming the target moves in one plane only, which of the following ocular movements must occur?
Dextroversion of the right eye and levoversion of the left eye
Divergence
Infraversion
Supravergence
Divergence
In order to maintain fixation on a target that is moved away from the patient, his eyes must diverge (rotate outwards away from the midline). A vergence is a binocular movement of the eyes such that the eyes move in opposite directions. A version is a binocular eye movement in which the eyes move in the same direction and of equal magnitude. Infraversion is a movement where both eyes look downwards. Although during divergence, the right eye technically moves slightly to the right (away from the midline) and the left eye moves slightly to the left (away from the midline) these movements cannot be termed dextroversion and levoversion respectively as a version infers movement of the eyes in the same direction. Supravergence is the movement of one eye upwards with respect to the other.
