Strabismus Measurements Flashcards
An examiner could use a __ while testing versions. Patient can then tell the examiner if white/ red light separate at any point to see if an incomitant deviation is presented.
Red lens
_ is eye a miss alignment or eyes that do not move normally caused by intocular muscle in balance. One fovea is not directed at the same object as the other can be congenitald or acquired
Strabismus
Strabismus can include
Accommodative strabismus Alternating Comitant Incomitant Intermittent Paralytic
cause “ risk factors” of strabismus
Family history
Refractive error
Medical conditions
_ caused by focusing efforts of the eyes trying to see clearly highly influenced by accommodative effort example;accommodative esotropia
Accommodative strabismus
Focusing on a stimulus at near causes miosis, accommodation and convergence. This is known as the_ 
Synkinetic near response
Types of accommodative esotropia include:
refractive, non-refractive and partially accommodation
_ can be from significant uncorrected hyperopia which forces the patient to exert excessive accommodation to focus images on the retina that’s causing increased convergence
Accommodative esotropia
-_ is when fixation and deviation alternate meaning either eye fixates in primary position (fixation held for 30-60 secs or more)vision typically is equal between the two eyes
Alternating tropia
_ The degree of eye misalignment is the same in all directions of the gaze
Comitant strabismus
_ is a term to describe a degree of misalignment that varies in different positions of gazes ( head tilt/turn typically to the null point)
Incomitant strabismus
_ A deviation in which the eyes are sometimes straight and other times an eye deviates
Intermittent strabismus
A_ is hidden or latent that occurs when the eye is deprived of a fixation target ( eye is covered- break fusion for the deviation to occur)
Phoria
With _ The degree of eye misalignment varies with positions of gaze(incomitant) and results from the paralysis or weakness of one or more extraocular muscles or nerves
Paralytic strabismus
( eye turned lateral) crossed diplopia
Exo
eye is turned medial ( uncrossed diplopia )
ESO
Eye is turned superiorly
Hyper
Eye is turned inferiorly
Hypo
We always record the higher eye
A _ is a Manifest Eye turn or deviation caused by extraocular muscle imbalance that the patient has no or very little control over. The patient is unable to keep the eye Straight with the power of fusion readily observable
Tropia
_ is the amount of deviation when the non-affected eye is fixating. _ is the amount of deviation when the paretic eye is fixating
Primary deviation
Secondary deviation
If a _ Is forced to take up fixation in the field of the under acting muscle it will result in over action of its yolk muscle because there is additional innervation sent to the weakened muscle to function. Due to hering’s law this additional innervation causes the yoke muscle ( of the non-paretic eye) to become overactive and it’s said to a secondary deviation
Paretic eye
Primary deviation is measured by holding the prism over the
Deviated eye
Secondary deviation are measured with cross-cover and prims , by holding the prism over the _
Fixating eye
The _ deviation is typically greater (in relation to prism diopters of deviation) than the primary deviation
Secondary
Right exotropia
RXT
Left exotropia
LXT
Right esotropia
RET
Left esotropia
LET
Right hypertropia
RHT
Left hypertropia
LHT
Exophoria
X
Esophoria
E
Right hyperphoria
RH
Left hyperphoria
LH
Intermittent tropia
Deviation with (T)
Alternating tropia
Alt
A pt who does not demonstrate a deviation of eye alignment is termed _ or _ which is the absence of eye deviation.
Ortho , orthophoric
Motility testing is typically done with _ so that the pt can fixate on the accommodative target at both distant and near
Best corrected visual acuity (BCVA)
_ is the angle created between the visual axis ( an imaginary line that connects fixation to the fovea) and the pupillary axis ( center of the curvature or the cornea and pupil)
Angle kappa
_ corneal reflex falls nasal to the center of the pupil ( in both eyes if pt is ortho and in then fixating eye is a tropia is present)
Positive angle kappa
_ is when the corneal reflex falls right on the center of the pupil
No angle kappa
_ corneal reflex falls temporally to the center of the pupil ( in both eyes if pt is ortho and fixating eye if a tropia is present) may give an illusion of an eso deviation
Negative angle kappa
The hirschberg test states one millimeter of reflex displacement equals approximately _ of eye alignment deviation which is based on the average pupil size of 4mm
7 degrees or 15 prism diopters
The _ uses prisms following the Hirshberg test to move the deviated reflex back into the position that is symmetrical with the reflex of the fixating Eye as it means of measuring the deviation
Krimsky test
Hirschberg is an _ based on mm of decentration while krimsky is the _
Estimation, measurement of deviation with prisms
_ gives the appearance of esotropia due to: less visible sclera, epicanthal folds, and/ or bridge of the nose. Hirschberg proves ortho
Pseudoesotropia
Hirschberg and krimsky test use an _ target and can be check at both _ and _
Accommodative, distant and near
Light reflex’s on cornea
Center: Normal Medially: exotropia Laterally: esotropia Inferiorly: hypertropia Superiorly: hypotropia
Hirschberg light reflex displacement is as follows
Pupillary boarder 2mm=15 degrees = 30 prism diopters
Mid iris is 4mm= 30 degrees =60 prism diopters
Limbus is 6mm= 45 degrees = 90 prism diopters
Corneal reflex is temporally you hold prism over the eye _ . Nasally _ superiorly _.
BO, BI, BU, BD
Cover testing includes three types which are _
Cover-uncover test, the alternate cover test and the simultaneous prism cover test
The _ is the test used to detect binocular fixation and rule out tropia or distinguish between a tropia and a phoria . It allows the patient to establish binocular fixation if possible. If there is no binocular fixation there is no tropia
Cover- uncover test
The _ is the only test that will differentiate a tropia from a phoria!
Cover uncover test
When looking for a tropia watch the _ as soon as you cover the opposite eye to see if it moves to pick up fixation . When tropia is present, once fixating eye is covered the tropic eye will move _
Uncovered eye , towards fixation
_ aka _ follows cover uncover testing (if no tropia ) and is used to bring out a phoria where one must alternate cover ( w occluded) _ times
Alternating cover test , cross cover test , 10-12 times
Not finding any phoria or tropia with cover uncover test
Ortho
When measuring a deviation with prism the apex of the prism points _ over the deviated eye
Vertical/ horizontal
Reasons to preform cover testing
Pt reports diplopia
Pt reports difficulty reading
Pt states they can’t read for long time
Complete exam
Purpose of cover uncover test and cross cover test includes
Tropia or phoria ( cover uncover test)
To see if a pt is fusing/both distance and near
If there is deviation once fusion is broken
_ is a condition when an eye drifts upward which may vary during the course of day unilateral or bilateral deviation ( can be unequal and not at the same time)
Dissociated vertical divergence
_ is preformed by simultaneously covering the The fixating eye at the same time the prism is placed in front of the Deviated eye. Test is repeated increase in prison powers until the deviated Eye no longer moves
Dissociated vertical deviation (dvd)
