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Flashcards in Classifications of Strabismus Deck (71)
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1
Q

Strabismus is manifest deviation of the visual axes of the eyes of at least 1 PD where:

A
  1. lines of sight from each eye are not pointed towards the same fixation point.
  2. bifoveal fixation is not present
  3. the object of regard is on the fovea of one eye and a non foveal retinal point of the deviating eye.
  4. the fusional vergence system can’t compensate for the misalignment of the visual axes.
2
Q

T/F When doing entrance tests check global and local stereopsis. only way to detect if bifocal fixation is present

A

true

3
Q

The prevalence of strabismus is 2- ___% of the population. There is no gender bias, except for Duane’s syndrome and thyroid eye disease. Strab is usually diagnosed by 3-4 years of age, its usually _______ and esotropia is more prevalent than exotropia.

A

6; hereditary

4
Q

What is the refractive etiology of strabismus?

A

the retinal image seen by one or both eyes may be so blurred or unequal that the images cannot be fused.

5
Q

what are organic causes of strabismus?

A

disease of the ocular structure or pathway that is unilateral or asymmetric; age of onset is a factor; disease early in dev usually results in an eso deviation due to excess tonus of convergence.

6
Q

What are some anatomic causes of strabismus

A
  1. abnormal orbital structure
  2. abnormal volume of retrobulbar tissue
  3. abnormal function of extra ocular muscles due to insertion, length or elasticity.
  4. abnormal anatomic arrangements of ligaments and fascia.
7
Q

what are innovational causes of strabismus

A
  1. abnormally low/high AC/A relationship
  2. poor motor fusion
  3. excessive or insufficient tonic innervation to the EOM’s
  4. Inadequate or excessive central coordination from brain
8
Q

What are central nervous system causes of strabismus

A
  1. Syndromes: poor central control/coordination occurs in patients with DS and Cerebral palsy
  2. Brain damage: can lead to intractable diplopia
  3. Psychosomatic causes: lead to spasm of the near reflex
9
Q

How can you detect the presence or absence of strabismus?

A
  1. direct observation
  2. hirschberg test
  3. unilateral cover test
10
Q

how do you detect the direction of the deviation?

A
  1. direct observation
  2. hirschberg test
  3. alternating cover test
11
Q

how do you detect the magnitude of the deviation

A
  1. direct observation
  2. hirschberg test
  3. krismky test
  4. alternating cover test
12
Q

1 mm = _____ PD

A

22

13
Q

how do you detect laterality (unilateral or alternating)

A
  1. direct observation
  2. hirschberg test
  3. bruckner test
  4. unilateral cover test
14
Q

how do you detect AC/A ratio?

A
  1. alternating cover test at distance and near

2. gradient AC/A

15
Q

how do you detect frequency of deviation (intermittent or constant)

A
  1. direct observation
  2. hirschberg test
  3. unilateral cover test
16
Q

what is comitancy

A

differences in magnitude of the deviation between the 9 positions of gaze with either eye fixating. angle of deviation is within physiologic limits with each eye fixating in turn & for a specific fixation distance; usually supra nuclear in origin.

17
Q

how do you detect comitancy?

A
  1. direct observation
  2. observing hirschberg images during versions
  3. alternating CT
  4. Parks 3 step test
  5. red glass test
  6. hess lancaster test
18
Q

what does noncomitant mean?

A

angle of deviation changes by more than 5 PD for a specific fixation distance either in the different directions of gaze or with each fixating in turn.
*frequently the result of damage to either the oculomotor, trochlear, and abducens nerve or nuclei that innervate the extra ocular muscles. lesions can occur anywhere from the nuclear level to the muscle itself.

19
Q

Esotropias, exotropias, monofixation syndrome, ______, and vertical deviations are all a part of comitant strabismus

A

microtropias

20
Q

deviations secondary to trauma/injury, deviations following surgical intervention, deviations due to MG, ______ retraction syndrome, brown’s tendon sheath syndrome, cranial nerve three paresis, and _____ paresis are all types of non comitant strabismus

A

duanes; muscle

21
Q

what are important questions to ask when you are doing case history for a strab patient

A
  1. frequency
  2. onset
  3. duration
  4. laterality
  5. associated signs and symptoms
22
Q

what are questions to ask for frequency?

A
  1. how often does the eye turn?
  2. is it constant or intermittent
  3. it it worse at a specific time of the day?
23
Q

what are questions to ask about onset?

A
  1. age of onset

2. mode of onset (sudden or gradual)

24
Q

what are questions to ask about duration

A

what was the timeline between when the strabismus was noted and when the treatment began?

25
Q

what are questions to ask about location/laterality

A
  1. does it occur at distance or at near?
  2. does the eye turn in a specific gaze only (non comitant)
  3. one eye or both eyes turn? (unilateral or alternating)
26
Q

what are questions to ask about associated signs/symptoms

A
  1. occur following trauma
  2. dizziness/ motion sickness
  3. headache
  4. blurred vision (possible amblyopia)
  5. diplopia
  6. head turn/tilt
  7. closure of an eye
  8. eyes hurt/tired
  9. no symptoms
27
Q

What are questions to ask about relief/previous treatment?

A
  1. glasses (do they wear them? do they work?)
  2. occlusion therapy
    - what type of occlusion
    - how long did you occlude?
    - which eye or both?
    - was the patient compliant with patching?
    - what was the efficacy? did the vision or eye turn improve?
  3. VT
  4. Surgery
    - when was the surgery (more than 1 surgery?)
    - what were the results
    - have your eyes changed over time following surgery? (consecutive strabismus)
28
Q

what are questions to ask about birth history

A
  1. birth weight
  2. premature birth
  3. any complications of birth mother during pregnancy
  4. any complications with the delivery
  5. did the mother deliver via c section
  6. how has perinatal care been
29
Q

what are developmental questions to ask

A
  1. at what age did your child sit up without support
  2. what age did child crawl
  3. did they crawl on their hands and knees
  4. what age did they walk
  5. what age did they say their first words
  6. any concerns regarding the growth and dev of child
30
Q

what can happen during pregnancy which can affect motor, visual/dev delays

A
  1. viral infection
  2. alcohol/drug abuse
  3. accident or infection
  4. hypertension
  5. smoking
  6. severe stress
31
Q

what can happen at birth which can affect motor/visual/dev delays

A
  1. prolonged labor
  2. forceps extraction
  3. C section
  4. fetal distress
  5. prematurity
32
Q

what can happen as a newborn to affect motor/visual/developmental delays

A
  1. low weight
  2. incubation
  3. problems with feeding
33
Q

what can happen during infancy which can affect motor/visual/developmental delays

A
  1. absence of crawling
  2. late learning to walk
  3. late learning to talk
34
Q

what can happen during childhood to affect motor/visual/developmental delays

A
  1. motion sickness
  2. difficulty learning to ride a bike
  3. difficulty learning to read/write
  4. difficulty learning to tell time
  5. poor eye hand coordination
35
Q

What are questions to ask about systemic health history

A
  1. childhood diseases: periods of time with the flu, periods of very high temp’s.
  2. injuries/bad falls
  3. any meds being taken
  4. known neurologic conditions: seizures, syndromes, ASD
36
Q

what are important family history questions to ask

A
  1. diabetes, hypertension, cancer
  2. glaucoma
  3. strabismus
  4. amblyopia
  5. binocular dysfunctions
  6. learning disabilities
37
Q

what are academic/educational questions to ask

A
  1. childs grade
  2. ever had educational eval
  3. IEP
  4. 504 plan at school
  5. are they in special education for any subjects
  6. tutoring or remediation in any subjects, what grade?
  7. behavior challenges in school?
38
Q

what to ask for previous/current therapies

A
  1. if child has been evaluated by an OT, PT, SLP, audiologist.
  2. results of those
  3. did the child receive or is the child currently receiving therapy
  4. current therapy goals
39
Q

What are the different types of esotropias

A
  1. pseudo strabismus
  2. congenital/infantile esotropia
  3. accommodative esotropia
  4. non accommodative esotropia
  5. sensory esotropia
  6. consecutive esotropia
  7. cyclic esotropia
40
Q

Esotropias are usually stable and constant, and associated with hyperopia. Up to 50% could have an associated vertical deviation due to overreaction of the ____ ____ muscles. Isotropy is usually larger in magnitude at near due to proximal and accommodative convergence.

A

inferior oblique

41
Q

In _______ strabismus, pt’s usually have prominent epicentral folds, reduced inter pupillary distance. Most children outgrow the isotropy as their facial features develop. clinical eval with hirschberg shows no esotropia present.

A

pseudo

42
Q

_____ esotropia has age of onset at 3-4 months and is due to tonic convergence. It delays developments in the ____ system.

A

congenital; vergece

43
Q

what is clinical eval of a pt who has congenital strabismus

A
  1. 40-60 PD at distance and near
  2. constant strab
  3. can be alternating
  4. NO accommodative component
  5. amblyopia in most pts due to a preferred fixating eye.
44
Q

what are motor anomalies of congenital esotropia

A
  1. cross fixation
  2. DVD: bilateral hyper deviation only seen with occlusion of an eye.
  3. Inferior oblique overaction
  4. nystagmus: rotary is bilateral and rhythmic and diminishes in the first 10 years of life. Latent is horizontal jerk nystagmus on occlusion of either eye, in which the fast phase is toward the uncovered eye.
45
Q

How do you treat congenital esotropia

A
  1. treat significant RE: >+2.50 in infants with esotropia.
  2. treat amblyopia through very careful occlusion schedule using alternate fixation as a measure of improvement.
  3. Surgery: best outcome is before 18 months, preferred before 1 year. bilateral medial rectus recession performed. post surgical outcome is 10 pd of esotropia or less. can result in microtropia/monofixation syndrome
  4. Prognosis: poor prognosis for a functional cure due to early onset during critical period, but good for cosmetic cure.
46
Q

Accommodative esotropia’s avg age of onset is 2 1/2 years but can be between ____ months and 7 years of age. These patients are usually hyperopic and have a _____ ratio. they respond well to glasses treatment.

A

6; AC/A

47
Q

People with refractive accommodative esotropia usually have symptoms of _____ estropia, diplopia, rubbing/closing eye during near tasks, and poor cosmesis. Size of deviation is usually the same at distance and near, usually intermittent due to unstable accommodation. ______is common, and usually high hyperopia (2-6 D) and usually have a ____ AC/A ratio

A

intermittent; alternation; normal

48
Q

Adaptations of refractive accommodative esotropia includes _______ at initial onset, & suppression. ARC is unlikely due to deviation being intermittent and variable. Treatment includes glasses which completely eliminates ET, (BF if high AC/A ratio), consider VT. Surgery is contraindicated.

A

diplopia

49
Q

Peak onset of non refractive accommodative esotropia is ____to 5 year old. Symptoms include intermittent esotropia at near only, rubbing/closing 1 eye during near tasks, no symptoms as suppression develops quickly and poor cosmesis. they ortho to slight eso at distance. They have an intermittent alternating strabismus, RE same as general population, and usually no amblyopia present due to ortho posture at distance.

A

2

50
Q

Pts with non refractive accommodative esotropia have high AC/A. Treat the ametropia, BF usually necessary and consider VT. ____ is contra indicated

A

surgery

51
Q

_______/partially accommodative esotropia is present even when the pt is wearing their full hyperopic rx and/or a BF. Age of onset is 1-3 yo. Deviation is

A

mixed; 40; anisometropia

52
Q

ARC and _____ scotoma are common in mixed/partially accommodative esotropia. Treatment includes refractive correction, consider BF with high AC/A ratio, consider prism if angle is 15 pd or less and fusion can be attained. Occlusion if amblyopia is present, consider VT, and consider surgery for large angles of non accommodative esotropia, greater than ______pd

A

suppression; 15

53
Q

what are the types of non accommodative esotropia

A
  1. early onset non accommodative esotropia
  2. acute acquired comitant non accommodative esotropia
  3. DI esotropia
  4. decompensated esotropia
  5. sensory esotropia
  6. consecutive esotropia
  7. cyclic esotropia
54
Q

Unlike infantile esotropia early onset non accommodative esotropia occurs at 6 months to _____ years of age. Etiology is innervational due to excess tonic convergence with poor control of negative fusional vergence and no restriction of muscles. Size of deviation is ____-70 pd at distance and near. Typically constant and alternating until a fixation preference develops.

A

2; 30

55
Q

T/F; Early onset non accommodative esotropia has a better prognosis

A

true

56
Q

What is the difference between accommodative and non accommodative esotropia

A

non accommodative esotropia has a better response to therapy, and presence of DVD, OIO and nystagmus is less common than in infantile esotropia.

57
Q

what are symptoms of acute acquired comitant non accommodative esotropia

A
  1. poor cosmesis
  2. sudden onset (rule out neurological issues/intracranial disease)
  3. diplopia initially, then adaptations occur
58
Q

Acute acquired comitant non accommodative esotropia has deviation of ____-30 pd but can go up to 60 pd. it is usually constant and unilateral, no paresis…insignificant refractive error

A

20

59
Q

when can amblyopia occur in acute acquired comitant non accommodative esotropia

A

before 6 years of age and if its unilateral.

60
Q

what are adaptations to acute acquired comitant non accommodative esotropia

A
  1. suppression
  2. diplopia
  3. anomalous correspondence
61
Q

What is a type of non accommodative esotropia that is present usually at distance, or is worse at distance than at near and usually develops suddenly.

A

divergence insufficiency esotropia

62
Q

Divergence insufficiency esotropia usually has onset after age ____ and has decreased negative fusional vergence at distance, ___ AC/A, and is usually due to neurologic process. It is important to rule out lateral rectus paresis (non comitant) or divergence paralysis. RE is the same as normal population and lack of sensory adaptations due to late onset.

A

10; low

63
Q

With DI esotropia, there is diplopia at _____, asthenopia and headaches. Strabismus is worse at _____. Deviation is _____, either constant or intermittent. Treatment require’s referral for neurologic etiology, correct refractive error, ____ prism for distance for the short/long term depending on personal factors, VT, but surgery is not necessarily indicated.

A

distance; distance; comitant

64
Q

A _____ esotropia is an esotropia that was previously maintained as an esophoria by negative fusional vergence. The _____ can no longer compensate for the esophoria.

A

decompensated; originally a phoria now a tropia

65
Q

Deviation of a decompensated esotropia is 10 - _____ pd at distance and near. It is _____, constant or intermittent, RE same as normal population, and no sensory adaptations due to late onset.

A

20

66
Q

How do you treat decompensated esotropia’s?

A
  1. correct refractive error
  2. consider prisms if personal situation warrants prescribing the minimum to allow fusion.
  3. consider VT
  4. consider surgery for large angles > 20 pd
67
Q

how does one develop sensory esotropia

A

due to a decrease or loss of visual function in one eye:

  • ptosis
  • corneal scar
  • cataract
  • -optic atrophy
  • macular scar
  • uncorrected RE/anisometropic amblyopia
68
Q

sensory esotropia has acuities of ____to LP

A

20/60

69
Q

If unilateral visual impairment occurs from birth to 5 years old, typically a _____esotropia will develop. Deviation is 10- _____pd and usually the same at distance and near. It is constant, unilateral, and can be comitant or non comitant. It can be associated with a hyper deviation or OIO/OSO. Amblyopia may be present due to an organic cause or the strabismus. Treatment is for cosmesis only.

A

sensory; 45

70
Q

______ esotropia refers to a tropia that results following surgery in a patient who had a previous exotropia. Symptoms include diplopia and asthenopia. Amblyopia may be present, can be caused by disruption/loss of bifoveal fusion. Magnitude of deviation varies. May be unilateral or alternating.

A

consecutive

71
Q

_____ esotropia is rare, etiology is unknown, and follows a circadian rhythm. Alternates with binocular vision on a _____ hour cycle, parents must log strab cycle. During ET phase, deviation is large: ____-70 pd and unilateral. During non ET phase, no manifest deviation is present, small eso may be measured, fusion and stereo are normal. Onset is in ____ to 4 year olds and some adults.

A

cyclic; 48; 30; 3