midterm Flashcards
in amblyopia, the best compensated visual acuity is _____ or worse in either or both eyes.
20/40
it is defined as a binocular or
monocular decrease in best corrected visual acuity (BCVA) due to pattern visual deprivation and/or abnormal binocular interaction during
visual immaturity for which there is no obvious ocular pathology or visual pathway defect and which in appropriate cases is reversible.
Amblyopia
Amblyopia is defined as a binocular or
monocular decrease in best corrected visual acuity (BCVA) due to _____________ during visual immaturity for which there is no obvious ocular pathology or visual pathway defect and which in appropriate cases is reversible (2)
-pattern visual deprivation
-abnormal binocular interaction
Before you diagnose a patient with amblyopia, make sure that he has no ocular __________(e.g. no glaucoma, no abnormalities during fundus or tumor, etc)
pathology
cause of amblyopia (1)
lack of proper eye development which results to Reduced Visual Acuity
meaning of:
lack of proper eye development which results to Reduced Visual Acuity
meaning something happened during the course of development. It may be during a critical period, at birth or 8-9 years old. there is a disease or an accident that may disrupt the proper development of the patient. It may lead to reduced visual acuity.
Categories of Amblyopia
(5)
-Strabismic Amblyopia
-Form Deprivation Amblyopia
-Anisometropia
-Isoametropia
-Refractive
types of form deprivation (3)
-Congenital Cataract
-Infantile Cataract
-ptosis
there is something that blocks the line of sight of the patient like congenital cataract or infantile cataract, or ptosis
Form Deprivation Amblyopia
when there is no input that can go inside the retina because the pupil is blocked
ptosis
unequal refractive error. usually you can consider if at least a 1.00D difference of right and left eye but if +1.00D, it doesn’t directly mean amblyopia, it must be
more than +1.00D
Anisometropia
chru or nope?
in anisometropia, If px is HYPEROPE: the patient is more prone to
develop amblyopia compared to Myope
chru.
ex: -5.00 and +5.00. Hyperope is more
prone to develop amblyopia compared to myope
approximately equal refractive error of both eyes but not necessarily equal
- ex: OD +5.25 and OS +5.00
Isoametropia
it is a type of amblyopia where in the higher the astigmatism, the higher the chance in developing amblyopia
Refractive
When both eyes are uncovered, both point towards the object of regard.
PHORIA
aka squint or tropia
STRABISMUS
chru or nope.
A strabismic patient does not perceive the world the same way, when the eye is turned, causing them to “suffer” from poor depth perception.
chru.
if a patient has strabismus, which of the 4 Circles of Skeffington is affected?
- Anti-gravity and Centering (major problem)
- Antigravity – answers the question WHERE AM I and where depth perception is concerned. So, if one eye is
turned then depth perception. - Centering – answers the question WHERE IS IT, and where binocular vision is concerned. If the patient has strab then the patient has problems in centering and binocular vision.
one eye is turned outwards, so if the
patient looks at the target, usually the target is placed BEHIND the real target.
Mismatch is present.
Exotropia
the target is perceived IN FRONT of the real target.
Esotropia
why is Brock string important?
Brock String is important because we can see how the patient localizes his space.
The patient cannot control his eyes due to: (5)
– POSTURE
– BALANCE
– CENTERING
– FIXATION
– IDENTIFICATION
the importance of centering (binocular vision) and anti gravity (depth perception) in strabismus
Binocular vision and depth perception are dependent upon visual development within these
2 circles. To accurately point both your eyes at an object, you must understand where you are and the distance between you and that object.
Not only are there interactions between all 4 circles, but experiencing depth perception will create feedback that enhances localization, centering, movement, and language.
chru or nope.
at 4 months of age, if the patient had fever or convulsions, there is a possibility that the patient may develop amblyopia or strabismus.
chru
how many months an infant develops binocular system?
4 months
Prevalence of amblyopia and strabismus.
- 4-6% of the population have amblyopia and/or strabismus.
prevalence of eso deviation
Eso deviations occur far more frequently than exo deviations, with a prevalence ratio of approximately three to one (3:1)
Esodeviation is more common rather than exo because exo deviation is associated with _______ (kids are more eso than exo)
neurological insult
Exo may be associated with _____ or _______
AV syndrome.
myasthenia gravis.
chru or nope.
There is no “critical period” in treating amblyopia and strabismus
chru.
We do not limit our patient in treating amblyopia and strab even if they’re in 30s, 40s, or 50s
however, there is a critical period in the development of amblyopia and strabismus at birth, or around 8-10 years old.
etiology/causes of Strabismus (3)
Anatomical
Optical
Innervational
due to impairment of cranial nerves III, IV, VI, which represent the majority of cases.
Innervational
(Strabismus cause)
refractive anisometropia, high RE, media opacities
- Optometrists can treat
- So if we identify that the patient’s strabismus is optical and we find out that he has a refractive error, we must first rule out the refractive error then we start from there
Optical –
abnormalities of EOM, ligaments, tendons, orbital contents.
optometrists must refer px to surgery
Anatomical
types of innervational cause of strab/ambly:
Paresis
Paralysis
paresis vs paralysis
Paresis - EOM has movement but is weak; there is just an innervational problem
Paralysis - the nerve is dead and the EOMs wont work. Also, during un
EOM has movement but is weak; there is just an innervational problem
Paresis
the nerve is dead and the EOMs wont work. Also, during uncover-cover, the eyes won’t move anymore
Paralysis
how to ensure that px eye muscles are not paralyzed?
perform cover tests and version tests.
before confirming that you can conduct vision rehabilitation for a strabismic patient, you must ensure that their eye muscles are not paralyzed by performing the tests above
chru or nope.
According to the Behavioral Optometry perspective, when strabismus is present, asymmetry in the body may be present.
chru.
how to distinguish a person has strab/ambly by only seeing their body language? (4)
-Observe their gait (manner of walking)
-stance
-titled shoulders
-compensatory head movement
Head Compensatory Movements (3)
- Face turn (either left or right) - horizontal deviation
- Chin elevation / depression - vertical deviation
- Head tilt to one shoulder (head tilt to right or left shoulder) - torsional deviation
a patient is right eso.
During primary gaze, the patient sees diplopia. To compensate, the px turns his head towards?
towards the right.
If a patient has hypertropia, which head compensatory movement is done?
chin depression is done
right movement of the head
eso OD
the socket cannot hold the whole bone so the tendency is there is displacement.
Hip dysplasia
the socket cannot hold the whole
bone so the tendency is there is displacement.
Hip dysplasia
patient may possibly lead in developing
amblyopia or strabismus because the normal development of px disrupted
Case 1: Born with incomplete hip development was put into a body cast for much of the first several months of life. Came in as a constant OD ET with a –6.00 in the OD and +0.50 OS. Afraid of driving off the right side of the road.
What are the problems?
- There is a problem in depth perception.
- The px has right esotropia
- the patient has no awareness of the right side of the road - There is a difference in the refractive error, the patient has antimetropia
is a condition in which one eye is myopic, while the fellow eye is hyperopic
Antimetropia
Born with incomplete hip development was put into a body cast for much of the first several months of life. Came in as a constant OD ET with a –6.00 in the OD and +0.50 OS. Afraid of driving off
the right side of the road.
Is there a difference in the image perceived by the patient between his right and left eyes?
Yes. However, the +0.50D doesn’t have an effect but the minus power (-6.00D) has an effect as it minifies the space
or image perceived. Thus, the patient’s space is more compressed. Px’s space is more compressed due to
- refractive error of high myopia in OD
- right esotropia
which method enables space compression?
MOTOR EQUIVALENCE
or CHALKBOARD CIRCLES.
procedure and materials for space compression
Materials: chalkboard and two chalks
Procedure: Have the patient look at the target and allow him to draw circles on his sides.
result for space compression
Result: Supposedly, the circles must somehow be symmetrical. If there is a big difference in the drawn circle, possibly, the patient has space
compression.
each eye is directed towards a
different object. it occurs when the images of the two different objects compete to be represented on the Internal representation of reality for the same location in space at the
same time
Confusion
Through, _______, we can understand the idea of superimposed images
Cheiroscope
the eyes deviate nasally. The right eye
will view the smiley while the left eye sees the sun. If different images are seen, in the retina, it will be _______ (leading to visual confusion).
superimposed
Resolving Confusion:
The visual system/person can resolve confusion in several ways: (4)
- Tune one channel out. Suppression (generally only portions of one channel of flow is tuned out).
- Physically cover an eye.
- usually we see this in kids when they have visual confusion, they squint or cover one eye - Blur one channel. Develop single sided refractive conditions
- Turn one eye in a different direction (increase deviation to remove confusion)
what type of revolving confusion is this?
OD and OS sees confusion (at first OU
is plano). Now the brain is confused with the images it perceives, so what it does is to ______ . At first small changes but eventually, the power increases until one eye is blur and only the
other eye sees to prevent confusion
blur one channel
it is a condition in which the amblyopic patient does not use the central foveal area under.
looking with the line of sight away from the fovea in an otherwise healthy eye.
Esotropia - nasal EF // Hyper - down EF
Exotropia - temporal EF // Hypo - up EF
Eccentric Fixation (monocular)
under monocular conditions
Eccentric
under binocular condition
Anomalous Retinal Correspondence -
Eccentric Fixation falls on: (4)
- Parafoveal – around the fovea
- Macular
- Paramacular – around the macula
- Peripheral
the person uses a point near the fovea to look with due to a loss of vision. The loss can be optical, retinal, or neurological.
Eccentric viewing
This can be seen with an ophthalmoscope using the grid.
eccentric fixation
-procedure to test for Eccentric Fixation
- performed through the same procedures of ophthalmoscopy
- you can occlude the amblyopic eye first and then later on, test the amblyopic eye
- direct and dim illumination
- After focusing on the patient’s fundus, ask the patient to look at the target center and identify the location of the grid
Sensory adaptation which allows strabismic patients to use both eyes without diplopia or confusion
Anomalous Retinal Correspondence
Angle of squint is small and the extrafoveal point is close to the fovea – to regain the binocular advantage, although anomalous
Anomalous/ Abnormal Retinal Correspondence
This results in the eye seeing binocularly single in spite of a manifest squint.
Anomalous/ Abnormal Retinal Correspondence
Under binocular conditions the fovea and the extrafoveal
Anomalous/ Abnormal Retinal Correspondence
ARC is common with _____(if deviation is less than 10 ∆D)
microstrabismus
ARC is common with microstrabismus, if deviation is:
less than 10 ∆D
NRC WITHOUT STRAB
single image
A 5-year-old px has strabismus, at that time, usually there is still normal retinal correspondence, so she sees double image. Years later, about 20 years old, so it is now a long-standing strabismus, most likely the patient’s visual system has adapted and has now ARC. Therefore, he now sees a single image
Is ARC okay in the optometrist perspective?
ARC is okay for the px because he can see a single image. But, ARC in the perspective of an optometrist, is not okay because this is temporary.
The stereopsis and depth perception are sacrificed in this situation.
Situation: Px w/ High Strab + No ARC
For example, a patient during the prism cover test has more than 50 ∆D (which is the largest value in the loose prism diopter) but there is still slight
movement. During W4D, she only sees 2 red dots.
assess.
- She has no ARC but she just suppressed it because the deviation is too big
Situation: Px w/ ARC + Microstrabismus
how to assess.
When you are dealing with microstrabismus with ARC (but they see single image), you must be careful in VT because there is a tendency that the px sees double.
For us, this is okay because it is slowly going back to NRC. But for these patients, it is not okay because they already know how to see single image, then you VT them, and now they’re seeing double vision again.. It is important to inform the patient of
what he will encounter.
TIPS
❖ ARC - Be careful with your VT plan
<3
Let’s say the target is the X, under binocular conditions, when both eyes are pointed towards the object, the image perceived by px must be projected in the right central fovea and left central fovea
Target @ Center
Device to assess eccentric fixation
Visuoscopy
NRC WITH STRAB (normal retinal correspondence)
double image
ARC WITH (long-standing) STRAB
single image
Usually confirmed with an ophthalmoscope in the case of retinal or optical pathology, but may need further testing in other cases.
eccentric viewing
usually we see this in kids when they have visual confusion, they squint or cover one eye
Physically cover an eye.
When an eye is covered the eye moves out of alignment and when uncovered, alignment is quickly restored
phoria
both eyes are looking at the target, at Right Nasal Retina and Left Temporal Retina.
Target @ right side of space
Corresponding means
the correct pairing.
Fovea stimulated should be right temporal retinal and left nasal fovea (it changes depending on where the target is located).
Target @ left side of space
it is when, without eye turn, both eyes are pointing directly at the object. The patient sees the single target
Normal retinal correspondence
means the eyes are correctly positioned, with both eyes looking in the same direction, with no eye turn.
Normal retinal correspondence (NRC)
When both eyes are open and uncovered, one eye is pointed at the target and the other eye is pointed somewhere else
strabismus
As optometrists, our only management is to
correct EOR but VT, not anymore.
Microstrabismus + ARC = are very well-adapted, if they have no problem, they do not need VT.
chru
Microstrabismus + ARC + no chief complaint + normal saccades + normal pursuits + no omission/skipping of words = usually NO VT and no need to prescribe VT
chru
You can observe body language of a patient with strab/ambly through: (3)
-during visual acuity tests
-during refraction
-preliminary tests
left movement of the head
exo OD
chin depression
hyper
chin elevation
hypo
the eyes deviate nasally. The right eye
will view the smiley while the left eye sees the sun.
If different images are seen, in the retina, it will be superimposed leading to:
visual confusion
When both the fovea have a common visual direction and the retinal elements nasal to the fovea in one eye corresponds to the retina, elements temporal to the fovea in the other eye.
Normal Retinal Correspondence
Optic Disc is always located
towards the:
nose or nasally
yellow part in the fundus is called
foveal reflex
the patient has eccentric fixation
because if you are an amblyope, you have a problem in the central vision (so reduced VA because VA is associated with central vision).
That is why he is not using the central fovea as fixation. He looks for an area in the fovea as fixation
amblyopic px does not use central vision
Found in amblyopes and strabismic amblyopes
Every line in the “grid” is equivalent to a prism diopter, and can be____ per line.
1 or 2 prism diopters
person perceives 2 objects as occupying the same location in visual space
visual confusion
When fovea of one eye has a common visual direction with an extrafoveal area in the other eye
ARC
In _____, the central part of the retina of each eye, known as the fovea, is correctly positioned and sees the images the person is looking at.
NRC
In NRC, the central part of the retina of each eye, known as the ______, is correctly positioned and sees the images the person is looking at.
fovea
what is amblyopia?
Amblyopia is defined as a binocular or monocular decrease in best corrected visual acuity (BCVA) due to pattern visual deprivation and abnormal binocular interaction during visual immaturity which there’s no obvious ocular pathology or visual pathway defect, which in appropriate cases is reversible
in hip dysplasia, the socket cannot hold the whole bone so the tendency is there is:
displacement
Patients with ARC lessens the_________. It is challenging for VT.
prognosis
generally only portions of one channel of flow is tuned out
Tune one channel out. Suppression
Develop single sided refractive conditions
Blur one channel
horizontal deviation. (which movement)
face turn (either left or right)
vertical deviation (which movement)
Chin elevation / depression
torsional deviation (which movement)
Head tilt to one shoulder (head tilt to right or left shoulder)
This law states that the yoke muscle receives equal and simultaneous innervation
Herring’s
This law states that contraction of a muscle is accompanied by relaxation of antagonist
Sherrington’s
If medial rectus contracts, the ____ relaxes
Lateral
If inferior rectus contracts, the _____ relaxes
Superior rectus
Give at least 2 causes of ambly
Anisometropia
Starbismic amblyopia
Equal size of retinal image
Iseikonia
When both eyes are open and uncovered, one eye is pointed at the target and the other eye is pointed somewhere else
Strabismus
If the patient has OD esotropia, he might adapt by turning his head towards the (r/l)?
Right (eso OD)
Synergist muscle during dextroversion
LIO RSO LIR LSR
Synergist muscle during levoversion
RSR RLR LIO LSO
Using an opque ocluder in unilateral cover test, the examiner observed outward movement of the uncovered left eye. The patient may have?
Exotropia
Using translucent occluder in unilateral cover test, the examiner observed no movement on the uncovered eye and an outward movement of the covered eye as seen through the occluder. The patient may have?
Exophoria
Using an opaque occluder, the examiner observed upward movement of uncovered eye, the patient may have?
Hypertropia
As the person looks in lower position of gaze, the eso deviation is larger
V syndrome esotropia
As the person looks in lower position of gaze, the eso deviation is less
A syndrome esotropia
The patient with strabismus will perceived the image as _____ if he has normal retinal correspondence
Double
Chin elevation and depression is seen in patient with what type of deviation?
Vertical
