Classifications of Strabismus

Question 1

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

Answer 1

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.

Question 2

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

Answer 2

true

Question 3

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.

Answer 3

6; hereditary

Question 4

What is the refractive etiology of strabismus?

Answer 4

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

Question 5

what are organic causes of strabismus?

Answer 5

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.

Question 6

What are some anatomic causes of strabismus

Answer 6

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.

Question 7

what are innovational causes of strabismus

Answer 7

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

Question 8

What are central nervous system causes of strabismus

Answer 8

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

Question 9

How can you detect the presence or absence of strabismus?

Answer 9

1. direct observation
2. hirschberg test
3. unilateral cover test

Question 10

how do you detect the direction of the deviation?

Answer 10

1. direct observation
2. hirschberg test
3. alternating cover test

Question 11

how do you detect the magnitude of the deviation

Answer 11

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

Question 12

1 mm = _____ PD

Answer 12

22

Question 13

how do you detect laterality (unilateral or alternating)

Answer 13

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

Question 14

how do you detect AC/A ratio?

Answer 14

1. alternating cover test at distance and near

2. gradient AC/A

Question 15

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

Answer 15

1. direct observation
2. hirschberg test
3. unilateral cover test

Question 16

what is comitancy

Answer 16

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.

Question 17

how do you detect comitancy?

Answer 17

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

Question 18

what does noncomitant mean?

Answer 18

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.

Question 19

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

Answer 19

microtropias

Question 20

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

Answer 20

duanes; muscle

Question 21

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

Answer 21

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

Question 22

what are questions to ask for frequency?

Answer 22

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

Question 23

what are questions to ask about onset?

Answer 23

1. age of onset

2. mode of onset (sudden or gradual)

Question 24

what are questions to ask about duration

Answer 24

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

Question 25

what are questions to ask about location/laterality

Answer 25

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)

Question 26

what are questions to ask about associated signs/symptoms

Answer 26

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

Question 27

What are questions to ask about relief/previous treatment?

Answer 27

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)

Question 28

what are questions to ask about birth history

Answer 28

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

Question 29

what are developmental questions to ask

Answer 29

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

Question 30

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

Answer 30

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

Question 31

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

Answer 31

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

Question 32

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

Answer 32

1. low weight 2. incubation 3. problems with feeding

Question 33

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

Answer 33

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

Question 34

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

Answer 34

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

Question 35

What are questions to ask about systemic health history

Answer 35

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

Question 36

what are important family history questions to ask

Answer 36

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

Question 37

what are academic/educational questions to ask

Answer 37

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?

Question 38

what to ask for previous/current therapies

Answer 38

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

Question 39

What are the different types of esotropias

Answer 39

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

Question 40

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.

Answer 40

inferior oblique

Question 41

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.

Answer 41

pseudo

Question 42

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

Answer 42

congenital; vergece

Question 43

what is clinical eval of a pt who has congenital strabismus

Answer 43

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.

Question 44

what are motor anomalies of congenital esotropia

Answer 44

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.

Question 45

How do you treat congenital esotropia

Answer 45

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.

Question 46

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.

Answer 46

6; AC/A

Question 47

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

Answer 47

intermittent; alternation; normal

Question 48

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.

Answer 48

diplopia

Question 49

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.

Answer 49

2

Question 50

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

Answer 50

surgery

Question 51

_______/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

Answer 51

mixed; 40; anisometropia

Question 52

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

Answer 52

suppression; 15

Question 53

what are the types of non accommodative esotropia

Answer 53

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

Question 54

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.

Answer 54

2; 30

Question 55

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

Answer 55

true

Question 56

What is the difference between accommodative and non accommodative esotropia

Answer 56

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

Question 57

what are symptoms of acute acquired comitant non accommodative esotropia

Answer 57

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

Question 58

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

Answer 58

20

Question 59

when can amblyopia occur in acute acquired comitant non accommodative esotropia

Answer 59

before 6 years of age and if its unilateral.

Question 60

what are adaptations to acute acquired comitant non accommodative esotropia

Answer 60

1. suppression 2. diplopia 3. anomalous correspondence

Question 61

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.

Answer 61

divergence insufficiency esotropia

Question 62

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.

Answer 62

10; low

Question 63

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.

Answer 63

distance; distance; comitant

Question 64

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

Answer 64

decompensated; originally a phoria now a tropia

Question 65

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.

Answer 65

20

Question 66

How do you treat decompensated esotropia's?

Answer 66

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

Question 67

how does one develop sensory esotropia

Answer 67

due to a decrease or loss of visual function in one eye: - ptosis - corneal scar - cataract - -optic atrophy - macular scar - uncorrected RE/anisometropic amblyopia

Question 68

sensory esotropia has acuities of ____to LP

Answer 68

20/60

Question 69

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.

Answer 69

sensory; 45

Question 70

______ 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.

Answer 70

consecutive

Question 71

_____ 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.

Answer 71

cyclic; 48; 30; 3